android-fragments

Twitter Login/Authentication in Android Fragment

走远了吗. — Sat, 20 Feb 2021 11:27:06 +0000

Twitter Login/Authentication in Android Fragment 走远了吗. 2021-02-20 19:27:06

问题

I am trying to implement a twitter login button in a fragment in Android using Fabric. I got it to work in an activity, but cannot get it working in a fragment.

Here is my TwitterFragment class (extends fragment)

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

TwitterAuthConfig authConfig = new TwitterAuthConfig(mTWITTER_KEY, mTWITTER_SECRET);
Fabric.with(super.getActivity(), new Twitter(authConfig));

View view = inflater.inflate(R.layout.twitter_fragment, container, false);

loginButton = (TwitterLoginButton) view.findViewById(R.id.twitter_login_button);

loginButton.setCallback(new Callback<TwitterSession>() {
    @Override
    public void success(Result<TwitterSession> result) {

        TwitterSession session = result.data;

        String msg = "@" + session.getUserName() + " logged in! (#" + session.getUserId() + ")";
        Toast.makeText(getActivity().getApplicationContext(), msg, Toast.LENGTH_LONG).show();
    }

    @Override
    public void failure(TwitterException exception) {
        Log.d("TwitterKit", "Login with Twitter failure", exception);
    }
});

return view;
}


@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    //loginButton.onActivityResult(requestCode, resultCode, data);
    Fragment fragment = getFragmentManager().findFragmentById(R.id.twitter_login_button);
    if (fragment != null) {
        fragment.onActivityResult(requestCode, resultCode, data);
    }
}

And my twitter_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="15dp">

    <com.twitter.sdk.android.core.identity.TwitterLoginButton
        android:id="@+id/twitter_login_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"/>

</LinearLayout>

I am getting this in the first 2 lines of the monitor

Authorization completed with an error
com.twitter.sdk.android.core.TwitterAuthException: Authorize failed.

Any ideas what the issue is?

Thank you,

回答1:

I had the same issue and solved it in this way:

in MainActivity, configure Twitter and add onActivityResult function:

TwitterAuthConfig authConfig = new TwitterAuthConfig(TWITTER_KEY, TWITTER_SECRET); Fabric.with(this, new Twitter(authConfig));

 @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        FragmentManager fragment = getSupportFragmentManager();
        if (fragment != null) {
       fragment.findFragmentByTag("LoginFragment").onActivityResult(requestCode, resultCode, data);
        }
        else Log.d("Twitter", "fragment is null");
    }

in your LoginFragment let your twitter button's onActivityResult

@Override

 public void onActivityResult(int requestCode, int resultCode, Intent data) {
            super.onActivityResult(requestCode, resultCode, data);
            twitterlogin.onActivityResult(requestCode, resultCode, data);
    }

Hope this helps, if not you, then some others with this frustrating issue.

回答2:

Add the twitter authentication and secret in the main activity.

private static final String TWITTER_KEY = "Your Key";
private static final String TWITTER_SECRET = "Your Secret";

Add the Twitter auth config in onCreate() method on main activity.

TwitterAuthConfig authConfig = new TwitterAuthConfig(TWITTER_KEY, TWITTER_SECRET); Fabric.with(this, new Twitter(authConfig));

Add the onActivityResult() method in the main Activity.

@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data);

List<Fragment> allFragments = getSupportFragmentManager().getFragments();
for (Fragment fragmento : allFragments) {
    if (fragmento instanceof TwitterSignIn) {
        ((TwitterSignIn) fragmento).onActivityResult(requestCode, resultCode, data);
    }
}

}

Create the object of twitter login button.
'TwitterLoginButton twitterLoginButton';

5> Update the code in on 'onCreateView' on fragment.

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState)
{
    // Inflate the layout for this fragment
    view = inflater.inflate(R.layout.fragment_twitter_sign_in, container, false);
    twitterLoginButton = (TwitterLoginButton)view.findViewById(R.id.twitterLogin);
    textView = (TextView) view.findViewById(R.id.textView);
    parentLayout = (RelativeLayout) view.findViewById(R.id.twitterFragmentParentLinearLayout);
    parentLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Utility.hideKeyboard(v, getContext());
        }
    });

    twitterLoginButton.setCallback(new Callback<TwitterSession>() {
        @Override
        public void success(Result<TwitterSession> result) {

            TwitterSession session = result.data;

            Twitter.getApiClient().getAccountService().verifyCredentials(true, false).enqueue(new Callback<User>(){
                @Override
                public void success(Result<User> userResult)
                {
                    try
                    {
                        User user = userResult.data;

                        textView.setText("UserNmae:"+user.name+"\nEmail:"+user.email+"\nImageUrl:"+user.profileImageUrl);
                    } catch (Exception e)
                    {
                        e.printStackTrace();
                    }
                }

                @Override
                public void failure(TwitterException e)
                {

                }
            });
            String msg = "@" + session.getUserName() + " logged in! (#" + session.getUserId() + ")";

        }

        @Override
        public void failure(TwitterException exception) {
            Log.d("TwitterKit", "Login with Twitter failure", exception);
        }
    });

    return view;
}

Finally add the 'onctivityResult()' in the fragment.

@Override public void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); twitterLoginButton.onActivityResult(requestCode, resultCode, data); }
Done, test the application it should be work.

来源：https://stackoverflow.com/questions/33701652/twitter-login-authentication-in-android-fragment

标签

android

android-fragments

twitter

Twitter Login/Authentication in Android Fragment

大憨熊 — Sat, 20 Feb 2021 11:26:18 +0000

Twitter Login/Authentication in Android Fragment 大憨熊 2021-02-20 19:26:18

问题

I am trying to implement a twitter login button in a fragment in Android using Fabric. I got it to work in an activity, but cannot get it working in a fragment.

Here is my TwitterFragment class (extends fragment)

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

TwitterAuthConfig authConfig = new TwitterAuthConfig(mTWITTER_KEY, mTWITTER_SECRET);
Fabric.with(super.getActivity(), new Twitter(authConfig));

View view = inflater.inflate(R.layout.twitter_fragment, container, false);

loginButton = (TwitterLoginButton) view.findViewById(R.id.twitter_login_button);

loginButton.setCallback(new Callback<TwitterSession>() {
    @Override
    public void success(Result<TwitterSession> result) {

        TwitterSession session = result.data;

        String msg = "@" + session.getUserName() + " logged in! (#" + session.getUserId() + ")";
        Toast.makeText(getActivity().getApplicationContext(), msg, Toast.LENGTH_LONG).show();
    }

    @Override
    public void failure(TwitterException exception) {
        Log.d("TwitterKit", "Login with Twitter failure", exception);
    }
});

return view;
}


@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    //loginButton.onActivityResult(requestCode, resultCode, data);
    Fragment fragment = getFragmentManager().findFragmentById(R.id.twitter_login_button);
    if (fragment != null) {
        fragment.onActivityResult(requestCode, resultCode, data);
    }
}

And my twitter_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="15dp">

    <com.twitter.sdk.android.core.identity.TwitterLoginButton
        android:id="@+id/twitter_login_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"/>

</LinearLayout>

I am getting this in the first 2 lines of the monitor

Authorization completed with an error
com.twitter.sdk.android.core.TwitterAuthException: Authorize failed.

Any ideas what the issue is?

Thank you,

回答1:

I had the same issue and solved it in this way:

in MainActivity, configure Twitter and add onActivityResult function:

TwitterAuthConfig authConfig = new TwitterAuthConfig(TWITTER_KEY, TWITTER_SECRET); Fabric.with(this, new Twitter(authConfig));

 @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        FragmentManager fragment = getSupportFragmentManager();
        if (fragment != null) {
       fragment.findFragmentByTag("LoginFragment").onActivityResult(requestCode, resultCode, data);
        }
        else Log.d("Twitter", "fragment is null");
    }

in your LoginFragment let your twitter button's onActivityResult

@Override

 public void onActivityResult(int requestCode, int resultCode, Intent data) {
            super.onActivityResult(requestCode, resultCode, data);
            twitterlogin.onActivityResult(requestCode, resultCode, data);
    }

Hope this helps, if not you, then some others with this frustrating issue.

回答2:

Add the twitter authentication and secret in the main activity.

private static final String TWITTER_KEY = "Your Key";
private static final String TWITTER_SECRET = "Your Secret";

Add the Twitter auth config in onCreate() method on main activity.

TwitterAuthConfig authConfig = new TwitterAuthConfig(TWITTER_KEY, TWITTER_SECRET); Fabric.with(this, new Twitter(authConfig));

Add the onActivityResult() method in the main Activity.

@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data);

List<Fragment> allFragments = getSupportFragmentManager().getFragments();
for (Fragment fragmento : allFragments) {
    if (fragmento instanceof TwitterSignIn) {
        ((TwitterSignIn) fragmento).onActivityResult(requestCode, resultCode, data);
    }
}

}

Create the object of twitter login button.
'TwitterLoginButton twitterLoginButton';

5> Update the code in on 'onCreateView' on fragment.

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState)
{
    // Inflate the layout for this fragment
    view = inflater.inflate(R.layout.fragment_twitter_sign_in, container, false);
    twitterLoginButton = (TwitterLoginButton)view.findViewById(R.id.twitterLogin);
    textView = (TextView) view.findViewById(R.id.textView);
    parentLayout = (RelativeLayout) view.findViewById(R.id.twitterFragmentParentLinearLayout);
    parentLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Utility.hideKeyboard(v, getContext());
        }
    });

    twitterLoginButton.setCallback(new Callback<TwitterSession>() {
        @Override
        public void success(Result<TwitterSession> result) {

            TwitterSession session = result.data;

            Twitter.getApiClient().getAccountService().verifyCredentials(true, false).enqueue(new Callback<User>(){
                @Override
                public void success(Result<User> userResult)
                {
                    try
                    {
                        User user = userResult.data;

                        textView.setText("UserNmae:"+user.name+"\nEmail:"+user.email+"\nImageUrl:"+user.profileImageUrl);
                    } catch (Exception e)
                    {
                        e.printStackTrace();
                    }
                }

                @Override
                public void failure(TwitterException e)
                {

                }
            });
            String msg = "@" + session.getUserName() + " logged in! (#" + session.getUserId() + ")";

        }

        @Override
        public void failure(TwitterException exception) {
            Log.d("TwitterKit", "Login with Twitter failure", exception);
        }
    });

    return view;
}

Finally add the 'onctivityResult()' in the fragment.

@Override public void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); twitterLoginButton.onActivityResult(requestCode, resultCode, data); }
Done, test the application it should be work.

来源：https://stackoverflow.com/questions/33701652/twitter-login-authentication-in-android-fragment

标签

android

android-fragments

twitter

How to know Fragment id for the fragment(s) provided by the tabbed activity template

老子叫甜甜 — Sat, 20 Feb 2021 02:16:20 +0000

How to know Fragment id for the fragment(s) provided by the tabbed activity template 老子叫甜甜 2021-02-20 10:16:20

问题

I have used the tabbed activity template provided by android studio but i can't happen to find the id for the different fragments used. the template had only one .xml and .java for all three fragments. I made a few changes and made three separate .xml and .java for the three fragments. But I can't figure out how to set the id for the different fragments either from .xml or in .java and without the id I can't perform inter fragment communication.

回答1:

Now for retrieving a fragment

Fragment f = getSupportFragmentManager().findFragmentByTag(getFragmentTag(mViewPager.getId(), mViewPager.getCurrentItem()));


public static String getFragmentTag(int viewId, long id) {
    return "android:switcher:" + viewId + ":" + id;
}

来源：https://stackoverflow.com/questions/39555081/how-to-know-fragment-id-for-the-fragments-provided-by-the-tabbed-activity-temp

标签

android

android-fragments

How to know Fragment id for the fragment(s) provided by the tabbed activity template

孤者浪人 — Sat, 20 Feb 2021 02:12:49 +0000

How to know Fragment id for the fragment(s) provided by the tabbed activity template 孤者浪人 2021-02-20 10:12:49

问题

回答1:

Now for retrieving a fragment

Fragment f = getSupportFragmentManager().findFragmentByTag(getFragmentTag(mViewPager.getId(), mViewPager.getCurrentItem()));


public static String getFragmentTag(int viewId, long id) {
    return "android:switcher:" + viewId + ":" + id;
}

来源：https://stackoverflow.com/questions/39555081/how-to-know-fragment-id-for-the-fragments-provided-by-the-tabbed-activity-temp

标签

android

android-fragments

RecyclerView does not update after removing an item [duplicate]

谁说我不能喝 — Sat, 20 Feb 2021 01:08:19 +0000

RecyclerView does not update after removing an item [duplicate] 谁说我不能喝 2021-02-20 09:08:19

问题

I have a RecyclerView horizontal image slider at the bottom of a fragment. The top of the fragment shows some details. Once the user clicks on the images at the bottom, the idea is to remove that image from the image slider and display its information in the fragment. Now the information shows up but the image does not gets removed from the RecyclerView. Here is what I have coded in the Onclick of the outermost layout. I have tried all the related answers that I could find but nothing worked. They all are in the code. Please let me know what am I doing wrong or what is missing.

holder.itemRowRelativeLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            if (isFiltering) {
                mItemList.clear();
                mItemList.addAll(mOriginalItemList);
                mItemList.remove(position);// At this point mItemList holds the correct. That is all the images but not the one that was clicked. 

                notifyItemRemoved(position); //solution 1
                notifyItemRangeRemoved(position, getItemCount()); // solution 2
                notifyItemRangeRemoved(0, getItemCount()); // solution 3
                notifyDataSetChanged();//solution 4
            }
        }
    });

Full Code of the adapter

public class ImageGallery16X9Adapter<T extends GalleryItem> extends RecyclerView.Adapter<ImageGallery16X9Adapter.GalleryItemViewHolder> {

public enum GalleryMode {
    All_SAME,
    FIRST_DIFFERENT
}

private Context mContext;
private BasePresenter mPresenter;
private List<T> mItemList;
private List<T> mOriginalItemList;
private GalleryItem mFirstItem;
private GalleryMode mGalleryMode;
private int deviceWidth, itemWidth, marginSingle, marginDouble;
private boolean isFiltering;

public ImageGallery16X9Adapter(Context context, BasePresenter presenter, GalleryMode galleryMode, List<T> itemList, GalleryItem firstItem, boolean isFiltering) {
    mContext = context;
    mPresenter = presenter;
    mGalleryMode = galleryMode;
    mItemList = new ArrayList<>(itemList);
    mOriginalItemList = new ArrayList<>(itemList);
    mFirstItem = firstItem;
    deviceWidth = CommonUtils.getDeviceWidth((Activity) mContext);
    itemWidth = (int) (deviceWidth * 0.9);
    marginDouble = (int) (deviceWidth * 0.05);
    marginSingle = (int) (deviceWidth * 0.025);
    this.isFiltering = isFiltering;
}

@Override
public GalleryItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    return new GalleryItemViewHolder(LayoutInflater.from(parent.getContext()).
            inflate(R.layout.row_image_gallery_16x9_item, parent, false));
}

@Override
public void onBindViewHolder(GalleryItemViewHolder holder, final int position) {
    RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) holder.itemRowRelativeLayout.getLayoutParams();
    RelativeLayout.LayoutParams rlParams = (RelativeLayout.LayoutParams) holder.itemImageView.getLayoutParams();
    layoutParams.width = itemWidth;
    rlParams.height = (int) (layoutParams.width * Constant.HEIGHT_FACTOR_16X9);

    if (position == 0) {
        layoutParams.leftMargin = marginDouble;
        layoutParams.rightMargin = 0;
        if (mGalleryMode == GalleryMode.FIRST_DIFFERENT) {
            holder.itemTitle.setVisibility(View.VISIBLE);
            holder.itemTitle.setText(mFirstItem.getItemTitle());
            if (mFirstItem.getItemImage() != null) {
                Picasso.with(MyApplication.getAppContext()).load(mFirstItem.getItemImage()).fit().placeholder(R.drawable.error_image).error(R.drawable.error_image).into(holder.itemImageView);
            } else {
                Picasso.with(MyApplication.getAppContext()).load(R.drawable.error_image).placeholder(R.drawable.error_image).error(R.drawable.error_image).fit().into(holder.itemImageView);
            }
            holder.itemDescription.setText(mFirstItem.getItemDescription());
        }
    } else {
        if (mGalleryMode == GalleryMode.FIRST_DIFFERENT) {
            if (position == mItemList.size()) {
                layoutParams.rightMargin = marginDouble;
            } else {
                layoutParams.rightMargin = 0;
            }
        } else {
            if (position == mItemList.size() - 1) {
                layoutParams.rightMargin = marginDouble;
            } else {
                layoutParams.rightMargin = 0;
            }
        }
        layoutParams.leftMargin = marginSingle;
    }

    int itemPosition = position;
    if (mGalleryMode == GalleryMode.FIRST_DIFFERENT && position > 0) {
        itemPosition = position - 1;
        T item = mItemList.get(itemPosition);
        holder.itemTitle.setVisibility(View.GONE);
        holder.itemDescription.setText(item.getItemDescription());
        Picasso.with(mContext).load(item.getItemImage()).fit().placeholder(R.drawable.error_image).error(R.drawable.error_image).into(holder.itemImageView);

    } else if (mGalleryMode == GalleryMode.All_SAME) {
        T item = mItemList.get(itemPosition);
        holder.itemTitle.setVisibility(View.GONE);
        holder.itemDescription.setText(item.getItemDescription());
        Picasso.with(mContext).load(item.getItemImage()).fit().placeholder(R.drawable.error_image).error(R.drawable.error_image).into(holder.itemImageView);
    }

    holder.itemRowRelativeLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (mGalleryMode == GalleryMode.FIRST_DIFFERENT) {
                if (position == 0) {
                    mPresenter.onItemClicked(mFirstItem);
                } else {
                    mPresenter.onItemClicked(mItemList.get(position - 1));
                }
            } else {
                mPresenter.onItemClicked(mItemList.get(position));
                if (isFiltering) {
                    mItemList.clear();
                    mItemList.addAll(mOriginalItemList);
                    mItemList.remove(position);

                    notifyItemRemoved(position); //solution 1
                    notifyItemRangeRemoved(position, getItemCount()); // solution 2
                    notifyItemRangeRemoved(0, getItemCount()); // solution 3
                    notifyDataSetChanged();//solution 4
                }
            }
        }
    });
}

@Override
public int getItemCount() {
    if (mGalleryMode == GalleryMode.FIRST_DIFFERENT)
        return mItemList.size() + 1;
    else
        return mItemList.size();
}


static class GalleryItemViewHolder extends RecyclerView.ViewHolder {
    private final TextView itemDescription, itemTitle;
    private final ImageView itemImageView, itemFavoriteImageView;
    private final RelativeLayout itemRowRelativeLayout;

    public GalleryItemViewHolder(View itemView) {
        super(itemView);
        itemRowRelativeLayout = (RelativeLayout) itemView.findViewById(R.id.rl_gallery_item_row);
        itemImageView = (ImageView) itemView.findViewById(R.id.img_gallery_item);
        itemFavoriteImageView = (ImageView) itemView.findViewById(R.id.img_gallery_item_favorite);
        itemTitle = (TextView) itemView.findViewById(R.id.txt_gallery_item_name);
        itemDescription = (TextView) itemView.findViewById(R.id.txt_gallery_item_description);
    }
}

}

回答1:

You need to use this 3 lines to make it work

mItemList.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position, mItemList.size());

回答2:

private void removerecyclerItem(DraftStoriesPojo list) {
        int current_position = allStoriesPojoList.indexOf(list);
        allStoriesPojoList.remove(current_position);
        notifyItemRemoved(current_position);
        notifyItemRangeChanged (current_position, getItemCount());
    }

回答3:

Declare a method in your custom RecylerView like below

public void DeleteData(int position){

        recordingItems.remove(position);
        notifyItemRemoved(position);
        notifyItemRangeChanged(position, recordingItems.size());
    }

and from mainActivity call

adapter.DeleteData(position);

回答4:

In order to have your code working you need to change Adapter constructor implementation as follows:

    public RecyclerViewAdapter(Context context, List<Model> model) {
    this.context = context;
    this.model = model;
}

Then in onActivityResult do like this:

    @Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == 4) {
        listModel.clear();
        listModel.addAll(repository.consDataBase(context));
        recyclerViewAdapter.notifyDataSetChanged();
    }
}

回答5:

No need to do so much complicated things there,simply remove and notify

holder.itemRowRelativeLayout.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        if (isFiltering) {
            mItemList.remove(position);
            notifyItemRemoved(position);
        }
    }
});

回答6:

Only add these two lines

mItemList.remove(position);
notifyDataSetChanged();

回答7:

You need to use these lines to make it work

mItemList.remove(position);
notifyDataSetChanged();

来源：https://stackoverflow.com/questions/45413292/recyclerview-does-not-update-after-removing-an-item

标签

RecyclerView does not update after removing an item [duplicate]

徘徊边缘 — Sat, 20 Feb 2021 01:07:13 +0000

RecyclerView does not update after removing an item [duplicate] 徘徊边缘 2021-02-20 09:07:13

问题

holder.itemRowRelativeLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            if (isFiltering) {
                mItemList.clear();
                mItemList.addAll(mOriginalItemList);
                mItemList.remove(position);// At this point mItemList holds the correct. That is all the images but not the one that was clicked. 

                notifyItemRemoved(position); //solution 1
                notifyItemRangeRemoved(position, getItemCount()); // solution 2
                notifyItemRangeRemoved(0, getItemCount()); // solution 3
                notifyDataSetChanged();//solution 4
            }
        }
    });

Full Code of the adapter

public class ImageGallery16X9Adapter<T extends GalleryItem> extends RecyclerView.Adapter<ImageGallery16X9Adapter.GalleryItemViewHolder> {

public enum GalleryMode {
    All_SAME,
    FIRST_DIFFERENT
}

private Context mContext;
private BasePresenter mPresenter;
private List<T> mItemList;
private List<T> mOriginalItemList;
private GalleryItem mFirstItem;
private GalleryMode mGalleryMode;
private int deviceWidth, itemWidth, marginSingle, marginDouble;
private boolean isFiltering;

public ImageGallery16X9Adapter(Context context, BasePresenter presenter, GalleryMode galleryMode, List<T> itemList, GalleryItem firstItem, boolean isFiltering) {
    mContext = context;
    mPresenter = presenter;
    mGalleryMode = galleryMode;
    mItemList = new ArrayList<>(itemList);
    mOriginalItemList = new ArrayList<>(itemList);
    mFirstItem = firstItem;
    deviceWidth = CommonUtils.getDeviceWidth((Activity) mContext);
    itemWidth = (int) (deviceWidth * 0.9);
    marginDouble = (int) (deviceWidth * 0.05);
    marginSingle = (int) (deviceWidth * 0.025);
    this.isFiltering = isFiltering;
}

@Override
public GalleryItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    return new GalleryItemViewHolder(LayoutInflater.from(parent.getContext()).
            inflate(R.layout.row_image_gallery_16x9_item, parent, false));
}

@Override
public void onBindViewHolder(GalleryItemViewHolder holder, final int position) {
    RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) holder.itemRowRelativeLayout.getLayoutParams();
    RelativeLayout.LayoutParams rlParams = (RelativeLayout.LayoutParams) holder.itemImageView.getLayoutParams();
    layoutParams.width = itemWidth;
    rlParams.height = (int) (layoutParams.width * Constant.HEIGHT_FACTOR_16X9);

    if (position == 0) {
        layoutParams.leftMargin = marginDouble;
        layoutParams.rightMargin = 0;
        if (mGalleryMode == GalleryMode.FIRST_DIFFERENT) {
            holder.itemTitle.setVisibility(View.VISIBLE);
            holder.itemTitle.setText(mFirstItem.getItemTitle());
            if (mFirstItem.getItemImage() != null) {
                Picasso.with(MyApplication.getAppContext()).load(mFirstItem.getItemImage()).fit().placeholder(R.drawable.error_image).error(R.drawable.error_image).into(holder.itemImageView);
            } else {
                Picasso.with(MyApplication.getAppContext()).load(R.drawable.error_image).placeholder(R.drawable.error_image).error(R.drawable.error_image).fit().into(holder.itemImageView);
            }
            holder.itemDescription.setText(mFirstItem.getItemDescription());
        }
    } else {
        if (mGalleryMode == GalleryMode.FIRST_DIFFERENT) {
            if (position == mItemList.size()) {
                layoutParams.rightMargin = marginDouble;
            } else {
                layoutParams.rightMargin = 0;
            }
        } else {
            if (position == mItemList.size() - 1) {
                layoutParams.rightMargin = marginDouble;
            } else {
                layoutParams.rightMargin = 0;
            }
        }
        layoutParams.leftMargin = marginSingle;
    }

    int itemPosition = position;
    if (mGalleryMode == GalleryMode.FIRST_DIFFERENT && position > 0) {
        itemPosition = position - 1;
        T item = mItemList.get(itemPosition);
        holder.itemTitle.setVisibility(View.GONE);
        holder.itemDescription.setText(item.getItemDescription());
        Picasso.with(mContext).load(item.getItemImage()).fit().placeholder(R.drawable.error_image).error(R.drawable.error_image).into(holder.itemImageView);

    } else if (mGalleryMode == GalleryMode.All_SAME) {
        T item = mItemList.get(itemPosition);
        holder.itemTitle.setVisibility(View.GONE);
        holder.itemDescription.setText(item.getItemDescription());
        Picasso.with(mContext).load(item.getItemImage()).fit().placeholder(R.drawable.error_image).error(R.drawable.error_image).into(holder.itemImageView);
    }

    holder.itemRowRelativeLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (mGalleryMode == GalleryMode.FIRST_DIFFERENT) {
                if (position == 0) {
                    mPresenter.onItemClicked(mFirstItem);
                } else {
                    mPresenter.onItemClicked(mItemList.get(position - 1));
                }
            } else {
                mPresenter.onItemClicked(mItemList.get(position));
                if (isFiltering) {
                    mItemList.clear();
                    mItemList.addAll(mOriginalItemList);
                    mItemList.remove(position);

                    notifyItemRemoved(position); //solution 1
                    notifyItemRangeRemoved(position, getItemCount()); // solution 2
                    notifyItemRangeRemoved(0, getItemCount()); // solution 3
                    notifyDataSetChanged();//solution 4
                }
            }
        }
    });
}

@Override
public int getItemCount() {
    if (mGalleryMode == GalleryMode.FIRST_DIFFERENT)
        return mItemList.size() + 1;
    else
        return mItemList.size();
}


static class GalleryItemViewHolder extends RecyclerView.ViewHolder {
    private final TextView itemDescription, itemTitle;
    private final ImageView itemImageView, itemFavoriteImageView;
    private final RelativeLayout itemRowRelativeLayout;

    public GalleryItemViewHolder(View itemView) {
        super(itemView);
        itemRowRelativeLayout = (RelativeLayout) itemView.findViewById(R.id.rl_gallery_item_row);
        itemImageView = (ImageView) itemView.findViewById(R.id.img_gallery_item);
        itemFavoriteImageView = (ImageView) itemView.findViewById(R.id.img_gallery_item_favorite);
        itemTitle = (TextView) itemView.findViewById(R.id.txt_gallery_item_name);
        itemDescription = (TextView) itemView.findViewById(R.id.txt_gallery_item_description);
    }
}

}

回答1:

You need to use this 3 lines to make it work

mItemList.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position, mItemList.size());

回答2:

private void removerecyclerItem(DraftStoriesPojo list) {
        int current_position = allStoriesPojoList.indexOf(list);
        allStoriesPojoList.remove(current_position);
        notifyItemRemoved(current_position);
        notifyItemRangeChanged (current_position, getItemCount());
    }

回答3:

Declare a method in your custom RecylerView like below

public void DeleteData(int position){

        recordingItems.remove(position);
        notifyItemRemoved(position);
        notifyItemRangeChanged(position, recordingItems.size());
    }

and from mainActivity call

adapter.DeleteData(position);

回答4:

In order to have your code working you need to change Adapter constructor implementation as follows:

    public RecyclerViewAdapter(Context context, List<Model> model) {
    this.context = context;
    this.model = model;
}

Then in onActivityResult do like this:

    @Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == 4) {
        listModel.clear();
        listModel.addAll(repository.consDataBase(context));
        recyclerViewAdapter.notifyDataSetChanged();
    }
}

回答5:

No need to do so much complicated things there,simply remove and notify

holder.itemRowRelativeLayout.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        if (isFiltering) {
            mItemList.remove(position);
            notifyItemRemoved(position);
        }
    }
});

回答6:

Only add these two lines

mItemList.remove(position);
notifyDataSetChanged();

回答7:

You need to use these lines to make it work

mItemList.remove(position);
notifyDataSetChanged();

来源：https://stackoverflow.com/questions/45413292/recyclerview-does-not-update-after-removing-an-item

标签

RecyclerView does not update after removing an item [duplicate]

狂风中的少年 — Sat, 20 Feb 2021 01:07:07 +0000

RecyclerView does not update after removing an item [duplicate] 狂风中的少年 2021-02-20 09:07:07

问题

holder.itemRowRelativeLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            if (isFiltering) {
                mItemList.clear();
                mItemList.addAll(mOriginalItemList);
                mItemList.remove(position);// At this point mItemList holds the correct. That is all the images but not the one that was clicked. 

                notifyItemRemoved(position); //solution 1
                notifyItemRangeRemoved(position, getItemCount()); // solution 2
                notifyItemRangeRemoved(0, getItemCount()); // solution 3
                notifyDataSetChanged();//solution 4
            }
        }
    });

Full Code of the adapter

public class ImageGallery16X9Adapter<T extends GalleryItem> extends RecyclerView.Adapter<ImageGallery16X9Adapter.GalleryItemViewHolder> {

public enum GalleryMode {
    All_SAME,
    FIRST_DIFFERENT
}

private Context mContext;
private BasePresenter mPresenter;
private List<T> mItemList;
private List<T> mOriginalItemList;
private GalleryItem mFirstItem;
private GalleryMode mGalleryMode;
private int deviceWidth, itemWidth, marginSingle, marginDouble;
private boolean isFiltering;

public ImageGallery16X9Adapter(Context context, BasePresenter presenter, GalleryMode galleryMode, List<T> itemList, GalleryItem firstItem, boolean isFiltering) {
    mContext = context;
    mPresenter = presenter;
    mGalleryMode = galleryMode;
    mItemList = new ArrayList<>(itemList);
    mOriginalItemList = new ArrayList<>(itemList);
    mFirstItem = firstItem;
    deviceWidth = CommonUtils.getDeviceWidth((Activity) mContext);
    itemWidth = (int) (deviceWidth * 0.9);
    marginDouble = (int) (deviceWidth * 0.05);
    marginSingle = (int) (deviceWidth * 0.025);
    this.isFiltering = isFiltering;
}

@Override
public GalleryItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    return new GalleryItemViewHolder(LayoutInflater.from(parent.getContext()).
            inflate(R.layout.row_image_gallery_16x9_item, parent, false));
}

@Override
public void onBindViewHolder(GalleryItemViewHolder holder, final int position) {
    RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) holder.itemRowRelativeLayout.getLayoutParams();
    RelativeLayout.LayoutParams rlParams = (RelativeLayout.LayoutParams) holder.itemImageView.getLayoutParams();
    layoutParams.width = itemWidth;
    rlParams.height = (int) (layoutParams.width * Constant.HEIGHT_FACTOR_16X9);

    if (position == 0) {
        layoutParams.leftMargin = marginDouble;
        layoutParams.rightMargin = 0;
        if (mGalleryMode == GalleryMode.FIRST_DIFFERENT) {
            holder.itemTitle.setVisibility(View.VISIBLE);
            holder.itemTitle.setText(mFirstItem.getItemTitle());
            if (mFirstItem.getItemImage() != null) {
                Picasso.with(MyApplication.getAppContext()).load(mFirstItem.getItemImage()).fit().placeholder(R.drawable.error_image).error(R.drawable.error_image).into(holder.itemImageView);
            } else {
                Picasso.with(MyApplication.getAppContext()).load(R.drawable.error_image).placeholder(R.drawable.error_image).error(R.drawable.error_image).fit().into(holder.itemImageView);
            }
            holder.itemDescription.setText(mFirstItem.getItemDescription());
        }
    } else {
        if (mGalleryMode == GalleryMode.FIRST_DIFFERENT) {
            if (position == mItemList.size()) {
                layoutParams.rightMargin = marginDouble;
            } else {
                layoutParams.rightMargin = 0;
            }
        } else {
            if (position == mItemList.size() - 1) {
                layoutParams.rightMargin = marginDouble;
            } else {
                layoutParams.rightMargin = 0;
            }
        }
        layoutParams.leftMargin = marginSingle;
    }

    int itemPosition = position;
    if (mGalleryMode == GalleryMode.FIRST_DIFFERENT && position > 0) {
        itemPosition = position - 1;
        T item = mItemList.get(itemPosition);
        holder.itemTitle.setVisibility(View.GONE);
        holder.itemDescription.setText(item.getItemDescription());
        Picasso.with(mContext).load(item.getItemImage()).fit().placeholder(R.drawable.error_image).error(R.drawable.error_image).into(holder.itemImageView);

    } else if (mGalleryMode == GalleryMode.All_SAME) {
        T item = mItemList.get(itemPosition);
        holder.itemTitle.setVisibility(View.GONE);
        holder.itemDescription.setText(item.getItemDescription());
        Picasso.with(mContext).load(item.getItemImage()).fit().placeholder(R.drawable.error_image).error(R.drawable.error_image).into(holder.itemImageView);
    }

    holder.itemRowRelativeLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (mGalleryMode == GalleryMode.FIRST_DIFFERENT) {
                if (position == 0) {
                    mPresenter.onItemClicked(mFirstItem);
                } else {
                    mPresenter.onItemClicked(mItemList.get(position - 1));
                }
            } else {
                mPresenter.onItemClicked(mItemList.get(position));
                if (isFiltering) {
                    mItemList.clear();
                    mItemList.addAll(mOriginalItemList);
                    mItemList.remove(position);

                    notifyItemRemoved(position); //solution 1
                    notifyItemRangeRemoved(position, getItemCount()); // solution 2
                    notifyItemRangeRemoved(0, getItemCount()); // solution 3
                    notifyDataSetChanged();//solution 4
                }
            }
        }
    });
}

@Override
public int getItemCount() {
    if (mGalleryMode == GalleryMode.FIRST_DIFFERENT)
        return mItemList.size() + 1;
    else
        return mItemList.size();
}


static class GalleryItemViewHolder extends RecyclerView.ViewHolder {
    private final TextView itemDescription, itemTitle;
    private final ImageView itemImageView, itemFavoriteImageView;
    private final RelativeLayout itemRowRelativeLayout;

    public GalleryItemViewHolder(View itemView) {
        super(itemView);
        itemRowRelativeLayout = (RelativeLayout) itemView.findViewById(R.id.rl_gallery_item_row);
        itemImageView = (ImageView) itemView.findViewById(R.id.img_gallery_item);
        itemFavoriteImageView = (ImageView) itemView.findViewById(R.id.img_gallery_item_favorite);
        itemTitle = (TextView) itemView.findViewById(R.id.txt_gallery_item_name);
        itemDescription = (TextView) itemView.findViewById(R.id.txt_gallery_item_description);
    }
}

}

回答1:

You need to use this 3 lines to make it work

mItemList.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position, mItemList.size());

回答2:

private void removerecyclerItem(DraftStoriesPojo list) {
        int current_position = allStoriesPojoList.indexOf(list);
        allStoriesPojoList.remove(current_position);
        notifyItemRemoved(current_position);
        notifyItemRangeChanged (current_position, getItemCount());
    }

回答3:

Declare a method in your custom RecylerView like below

public void DeleteData(int position){

        recordingItems.remove(position);
        notifyItemRemoved(position);
        notifyItemRangeChanged(position, recordingItems.size());
    }

and from mainActivity call

adapter.DeleteData(position);

回答4:

In order to have your code working you need to change Adapter constructor implementation as follows:

    public RecyclerViewAdapter(Context context, List<Model> model) {
    this.context = context;
    this.model = model;
}

Then in onActivityResult do like this:

    @Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == 4) {
        listModel.clear();
        listModel.addAll(repository.consDataBase(context));
        recyclerViewAdapter.notifyDataSetChanged();
    }
}

回答5:

No need to do so much complicated things there,simply remove and notify

holder.itemRowRelativeLayout.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        if (isFiltering) {
            mItemList.remove(position);
            notifyItemRemoved(position);
        }
    }
});

回答6:

Only add these two lines

mItemList.remove(position);
notifyDataSetChanged();

回答7:

You need to use these lines to make it work

mItemList.remove(position);
notifyDataSetChanged();

来源：https://stackoverflow.com/questions/45413292/recyclerview-does-not-update-after-removing-an-item

标签

getActivity from fragment inside View pager return null

有些话、适合烂在心里 — Thu, 18 Feb 2021 22:15:11 +0000

getActivity from fragment inside View pager return null 有些话、适合烂在心里 2021-02-19 06:15:11

问题

I have a View pager inside of Fragment Activity and the View pager Contain two fragment at the start of the activity i have a rest request and when i get the response i want to update the Views inside of each fragment and in each one i'm using getActivity but my problem is the i always get null pointer exception on getActivity just on tablet Devices but i didn't get this issue on mobile phones

that's my pager adapter

public class Guide_ViewPager_adapter extends FragmentStatePagerAdapter {
    private Guides_fragment guide_frag = new Guides_fragment();
    private Maps_fragment maps_frag = new Maps_fragment();

    public Guide_ViewPager_adapter(FragmentManager fm){
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                return guide_frag;
            case 1:
                return maps_frag;
        }
        return  null;

    }

    @Override
    public int getCount() {
        return 2;
    }
}

LogCat snippet:

FATAL EXCEPTION: main Process: android.vi.com.vad, PID: 9554 java.lang.NullPointerException at android.vi.com.vad.Guides_fragment.update(Guides_fragment.java:138) at android.vi.com.vad.Guide_activity$GuideTask.onPostExecute(Guide_activity.java:213) at android.vi.com.vad.Guide_activity$GuideTask.onPostExecute(Guide_activity.java:165) at android.os.AsyncTask.finish(AsyncTask.java:632) at android.os.AsyncTask.access$600(AsyncTask.java:177) at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:149) at android.app.ActivityThread.main(ActivityThread.java:5234) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609) at dalvik.system.NativeStart.main(Native Method)

This is the method that i call it from inside the activity when the data loaded

public void update(String result) {
    if (animation != null) {
        animation.reset();
        animation.cancel();
    }
    if (loaderImage != null) {
        loaderImage.clearAnimation();
        loaderImage.setVisibility(View.GONE);
    }
    if (result.equalsIgnoreCase("null")) {
        if (errorImage != null) {
            errorImage.setVisibility(View.VISIBLE);
        }
    } else {
        Guide_GridView_adapter adapter = new Guide_GridView_adapter(activity.getApplicationContext(), Guide_activity.Downloads_Guides);
        guides_gridView.setAdapter(adapter);
        adapter.notifyDataSetChanged();
    }
}

and here when I set value to activity:

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    this.activity = getActivity();
}

回答1:

I have solved my problem by calling setRetainInstance(true) in Fragment onCreate()

 @Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setRetainInstance(true);
}

回答2:

Why do you need to call getActivity? The activity is passed in as a parameter? ie

@Override
public void onAttach(Activity activity) {
  super.onAttach(activity);
  this.activity = activity;
}

Having said that if you are coding to the latest API levels onAttachActiviy(Activity) is deprecated and you should be using onAttachActivity(Context) instead

see Android Fragment onAttach() deprecated

来源：https://stackoverflow.com/questions/34157262/getactivity-from-fragment-inside-view-pager-return-null

标签

android

android-fragments

android-viewpager

What's the proper way to setup an Android PreferenceFragment?

你离开我真会死。 — Thu, 18 Feb 2021 13:58:24 +0000

What's the proper way to setup an Android PreferenceFragment? 你离开我真会死。 2021-02-18 21:58:24

问题

I'm trying to implement a basic settings activity in an Android app and either get a blank white screen or a crash. The documentation and samples I've seen aren't helping because they're either old or inconsistent. For example, depending on where you look, the settings activity should either extend Activity, PreferenceActivity, or AppCompatPreferenceActivity (part of the File>New>Activity>Settings Activity).

developer.android.com says you should implement the following:

public class SettingsActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Display the fragment as the main content.
        getFragmentManager().beginTransaction()
            .replace(android.R.id.content, new SettingsFragment())
            .commit();
    }
}

Yet, the Settings Activity generated in Android Studio uses does not make this call for any of the three fragments it creates. It uses preference headers.

So here are my questions:

If you're using a simple, single preferences.xml file with a single PreferenceFragment and pre-API 19 compatibility is not a requirement, what class should SettingsActivity extend? Activity, PreferenceActivity, or AppCompatPreferenceActivity (for all its support methods and delegation)?
Do you need to call getFragmentManager().beginTransaction().replace(android.R.id.content, new SettingsFragment()).commit() in SettingsActivity.onCreate()?
With various combinations, I'm either getting a blank white settings screen with no action bar or a crash. What's the right way to setup a single PreferencesFragment within an activity that displays the app action bar?

回答1:

what class should SettingsActivity extend?

What worked for me was extending AppCompatActivity.

static final String ANIMATION = "animation" ;
static final String COUNTDOWN_ON_OFF = "countdown_on_off";

@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);

    if (getFragmentManager().findFragmentById(android.R.id.content) == null)
    {
        getFragmentManager().beginTransaction().add(android.R.id.content, new Prefs()).commit();
    }
}

I kicked out all the generated code related to preference headers and kept some template methods/ variables (which Android Studio generated in some earlier version) for my PreferenceFragment

public static class Prefs extends PreferenceFragment
{
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.preferences);

        // Bind the summaries of EditText/List/Dialog/Ringtone preferences
        // to their values. When their values change, their summaries are
        // updated to reflect the new value, per the Android Design
        // guidelines.

        // findPreference() uses android:key like in preferences.xml !

        bindPreferenceSummaryToValue(findPreference(ANIMATION));

    }
}

A static method in my Activity class (adapted from the template). You may want to check for other preference types:

 /**
 * Binds a preference's summary to its value. More specifically, when the
 * preference's value is changed, its summary (line of text below the
 * preference title) is updated to reflect the value. The summary is also
 * immediately updated upon calling this method. The exact display format is
 * dependent on the type of preference.
 *
 * @see #sBindPreferenceSummaryToValueListener
 */
private static void bindPreferenceSummaryToValue(Preference preference)
{
    // Set the listener to watch for value changes.
    preference.setOnPreferenceChangeListener(sBindPreferenceSummaryToValueListener);

    // Trigger the listener immediately with the preference's
    // current value.

    if (preference instanceof CheckBoxPreference)
    {
        sBindPreferenceSummaryToValueListener.onPreferenceChange(preference,
                                                                 PreferenceManager
                                                                         .getDefaultSharedPreferences(preference.getContext())
                                                                        .getBoolean(preference.getKey(), true));
    }
    else
    {
        sBindPreferenceSummaryToValueListener.onPreferenceChange(preference,
                                                                 PreferenceManager
                                                                         .getDefaultSharedPreferences(preference.getContext())
                                                                         .getString(preference.getKey(), ""));
    }
}

And finally, the Preference.OnPreferenceChangeListener as static variable in the Activity (also adapted from the template):

   /**
 * A preference value change listener that updates the preference's summary
 * to reflect its new value.<br>
 * template by Android Studio minus Ringtone Preference
 */
private static Preference.OnPreferenceChangeListener sBindPreferenceSummaryToValueListener = new Preference.OnPreferenceChangeListener()
{
    @Override
    public boolean onPreferenceChange(Preference preference, Object value)
    {
        String stringValue = value.toString();

        if (preference instanceof ListPreference)
        {
            // For list preferences, look up the correct display value in
            // the preference's 'entries' list.
            ListPreference listPreference = (ListPreference) preference;
            int index = listPreference.findIndexOfValue(stringValue);

            // Set the summary to reflect the new value.
            preference.setSummary(
                    index >= 0
                            ? listPreference.getEntries()[index]
                            : null);

        }
        else if (preference instanceof RingtonePreference)
        {
            // my app didn't need that
            return true;
        }
        else if (preference instanceof CheckBoxPreference)
        {
            Context ctx = preference.getContext();
            boolean isChecked = (Boolean) value;

            if (preference.getKey().equals(ANIMATION))
            {
                preference.setSummary(isChecked ? ctx.getString(R.string.sOn) : ctx.getString(R.string.sOff));
            }
            else if (preference.getKey().equals(COUNTDOWN_ON_OFF))
            {
                preference.setSummary(isChecked ? ctx.getString(R.string.sWhenPaused) : ctx.getString(R.string.sNever) );
            }
        }
        else
        {
            // For all other preferences, set the summary to the value's
            // simple string representation.
            preference.setSummary(stringValue);
        }
        return true;
    }
};
}

回答2:

Let's say we want to have a settings screen with one checkbox preference fragment as shown below:

Here is a step by step guide on how to build a settings activity where you can add some preferences to toggle or change the configurations for your Android app:

Add a dependency for support of preference fragment in build.gradle file for app module:
```
dependencies {
    compile 'com.android.support:preference-v7:25.1.0'
}
```
Add xml Android resource directory inside res directory.

Inside xml directory, add a new XML resource file named pref_visualizer.xml as below. We're going to add one check-box preference fragment inside it.

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
    <CheckBoxPreference
        android:defaultValue="true"
        android:key="show_base"
        android:summaryOff="Bass will not be shown currently."
        android:summaryOn="Bass will be shown currently."
        android:title="Show Bass"
        />
</PreferenceScreen>

PreferenceScreen is the root tag which can hold as many preference fragments as you want. If you want to add more configurations of type list or text box then you need to add it here as a child of PreferenceScreen tag.

Add a new Java class named SettingsFragment which will host PreferenceScreen. It should extend PreferenceFragmentCompat class as shown below:

import android.content.SharedPreferences;
import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
import android.os.Bundle;
import android.support.v7.preference.CheckBoxPreference;
import android.support.v7.preference.EditTextPreference;
import android.support.v7.preference.ListPreference;
import android.support.v7.preference.Preference;
import android.support.v7.preference.PreferenceFragmentCompat;
import android.support.v7.preference.PreferenceScreen;
import android.widget.Toast;


public class SettingsFragment extends PreferenceFragmentCompat {


@Override
public void onCreatePreferences(Bundle bundle, String s) {
        addPreferencesFromResource(R.xml.pref_visualizer);
    }
}

Now comes the final part where we build the association between an activity in the app and SettingsFragment class which hosts PreferenceScreen. Add a new activity named SettingsActivity which inherits from AppCompatActivity class. SettingsActivity class will act as the container for PreferenceScreen.

Java file for SettingsActivity:

import android.support.v4.app.NavUtils;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MenuItem;

public class SettingsActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_settings);
}

}

Layout file for SettingsActivity is shown below (activity_settings.xml). Here android.name property is the crux. It connects this activity to any of the classes present in your entire project which are inheriting from PreferenceFragmentCompat class. I had only one such class named SettingsFragment. You might have more than one class inheriting from PreferenceFragmentCompat class if you app has multiple settings screen.

<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/activity_settings"
    android:name="android.example.com.visualizerpreferences.SettingsFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

You're all set!

回答3:

Here's on Kotlin and android-x :

gradle:

implementation 'androidx.appcompat:appcompat:1.1.0-rc01'
implementation 'androidx.core:core-ktx:1.2.0-alpha02'
implementation 'androidx.constraintlayout:constraintlayout:2.0.0-beta2'
implementation 'com.google.android.material:material:1.1.0-alpha08'
implementation "androidx.preference:preference-ktx:1.1.0-rc01"
implementation 'androidx.core:core-ktx:1.2.0-alpha02'
implementation 'androidx.collection:collection-ktx:1.1.0'
implementation 'androidx.fragment:fragment-ktx:1.2.0-alpha01'

MainActivity.kt

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        if (savedInstanceState == null)
            supportFragmentManager.commit { replace(android.R.id.content, PrefsFragment()) }
    }

    class PrefsFragment : PreferenceFragmentCompat() {
        override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
            setPreferencesFromResource(R.xml.preferences, rootKey)
        }
    }
}

preferences.xml

<androidx.preference.PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">

  <androidx.preference.Preference android:title="hello"/>
</androidx.preference.PreferenceScreen>

回答4:

In addition to answer given by RBT, a Preference Theme must be specified otherwise the app will crash with an IllegalStateException.

In styles.xml file, just add the following line in Activity’s theme

<item name="preferenceTheme">@style/PreferenceThemeOverlay</item>

来源：https://stackoverflow.com/questions/45066520/whats-the-proper-way-to-setup-an-android-preferencefragment

标签

DialogFragment.dismiss crashing with NullPointerException

ε祈祈猫儿з — Thu, 18 Feb 2021 00:54:41 +0000

DialogFragment.dismiss crashing with NullPointerException ε祈祈猫儿з 2021-02-18 08:54:41

问题

I'm doing some background work and showing a DialogFragment while I do that. Once my work is done and the relevant callback is invoked, I dismiss the dialog. When I do, I get a crash caused by a NPE in the android source, here:

void dismissInternal(boolean allowStateLoss) {
        if (mDialog != null) {
            mDialog.dismiss();
            mDialog = null;
        }
        mRemoved = true;
        if (mBackStackId >= 0) {
            getFragmentManager().popBackStack(mBackStackId,
                    FragmentManager.POP_BACK_STACK_INCLUSIVE);
            mBackStackId = -1;
        } else {
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            ft.remove(this);
            if (allowStateLoss) {
                ft.commitAllowingStateLoss();
            } else {
                ft.commit();
            }
        }
    }

specifically at the line: FragmentTransaction ft = getFragmentManager().beginTransaction();

回答1:

This may also occur when you call dismiss() before you have called show() like Sogger said.

After Dialog object is constructed but before dialog is not showed, if (mDialog != null) can be passed and NullPointerException will occur.

When you check if mDialog is null or not,

if (mDialog != null) {
    mDialog.dismiss();
    mDialog = null;
}

Add more conditions like below,

if ((mDialog != null) && mDialog.isAdded() && mDialog.isResumed()) {
    mDialog.dismiss();
    mDialog = null;
}

I think that mDialog.isAdded() condition might be enough...

回答2:

Simplest solution is to check "getFragmentManager()" for "null" before calling "dismiss()" method. Also you can extend "DialogFragment" class and override method "dismiss()" to check it there:

@Override
public void dismiss()
{
    if (getFragmentManager() != null) super.dismiss();
}

回答3:

I know this message is old but I ran into a similar case that I needed to solvew without refactoring or changing a lot of code. Hope it's useful for somebody

   package com.example.playback;

import android.os.Bundle;
import android.support.v4.app.DialogFragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class SaferDialogFragment extends DialogFragment {

    private boolean allowStateLoss = false;
    private boolean shouldDismiss = false;

    public SaferDialogFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setRetainInstance(true);
    }

    @Override
    public void onStart() {
        super.onStart();
        //check if we should dismiss the dialog after rotation
        if (shouldDismiss) {
            if (allowStateLoss)
                dismissAllowingStateLoss();
            else
                dismiss();
        }
    }

    @Override
    public void dismiss() {
        if (getActivity() != null) { // it's "safer" to dismiss
            shouldDismiss = false;
            super.dismiss();
        } else {
            shouldDismiss = true;
            allowStateLoss = false;
        }
    }

    @Override
    public void dismissAllowingStateLoss() {
        if (getActivity() != null) { // it's "safer" to dismiss
            shouldDismiss = false;
            super.dismissAllowingStateLoss();
        } else
            allowStateLoss = shouldDismiss = true;
    }

    //keeping dialog after rotation
    @Override
    public void onDestroyView() {
        if (getDialog() != null && getRetainInstance())
            getDialog().setDismissMessage(null);
        super.onDestroyView();
    }



    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        /** omitted code **/
        return super.onCreateView(inflater, container, savedInstanceState);
    }
}

回答4:

My bet would be that the code you posted is from the background thread... you aren't allowed to update the UI from anywhere other than the UI thread.

You can use onPostExecute() or runOnUiThread() to achieve your goal (if my guess is right about what is happening)

回答5:

Checking if it's Visible before dimissing could avoid this null pointer exception

    if (mDialog != null && mDialog.isVisible) {
        mDialog.dismiss();
        mDialog = null;
    }

回答6:

The callback which is invoked is probably on the activity which is or should be destroyed (after orientation change), also the progress dialog might have been instantiated with that same activity. This might cause the NPE. Callbacks on activities should not be invoked from background tasks, to prevent these kinds of problems. Decouple the background task from the activity, for example using otto, or prevent the background task from invoking the (to be) destroyed activity.

This is some code of mine:

static inner class of activity:

    public static class ProgressDialogFragment extends DialogFragment {
    ProgressDialog dialog;

    public ProgressDialogFragment() {
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        dialog = new ProgressDialog(getActivity(), getTheme());
        dialog.setTitle(getString(R.string.please_wait));
        dialog.setMessage(getString(R.string.uploading_picture));
        dialog.setIndeterminate(true);
        dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
        return dialog;
    }

}

Otto subscription in activity:

@Subscribe
public void onUploadEvent(UploadAvatarEvent uploadAvatarEvent) {
    switch (uploadAvatarEvent.state) {
        case UploadAvatarEvent.STATE_UPLOADING:
            if (!mProgressDialog.isAdded()) {
                mProgressDialog.show(getFragmentManager(), TAG_PROGRESS_DIALOG);
            }
            break;
        case UploadAvatarEvent.STATE_UPLOAD_SUCCES:
            mProgressDialog.dismiss();
            break;
        case UploadAvatarEvent.STATE_UPLOAD_ERROR:
            mProgressDialog.dismiss();
            break;
    }
}

onCreate() in activity:

        mProgressDialog = (ProgressDialogFragment) getFragmentManager().findFragmentByTag(TAG_PROGRESS_DIALOG);
    if (mProgressDialog == null) {
        mProgressDialog = new ProgressDialogFragment();
    }

来源：https://stackoverflow.com/questions/10526743/dialogfragment-dismiss-crashing-with-nullpointerexception

标签

android

android-fragments