1. 技术文章
  2. Background color or Images shuffling on scrolling in recyclerview?

Background color or Images shuffling on scrolling in recyclerview?

由 杀马特。学长 韩版系。学妹 提交于 2019-11-28 12:42:33
Xaver Kapeller

I have created a working example of what you are trying to accomplish. The source of the errors you experience is mostly that you don't understand view recycling. I am not going to explain the whole thing to you now, but anyway here is the example:

For the example I used this layout for each row:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    android:id="@+id/background"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="80dp">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"/>

</FrameLayout>

I used this model:

public class ExampleModel {

    private final int mColor;
    private final String mText;

    public ExampleModel(int color, String text) {
        mColor = color;
        mText = text;
    }

    public int getColor() {
        return mColor;
    }

    public String getText() {
        return mText;
    }
}

And this view holder:

public class ExampleViewHolder extends RecyclerView.ViewHolder {

    private final FrameLayout mBackground;
    private final TextView mTextView;

    public ExampleViewHolder(View itemView) {
        super(itemView);

        mBackground = (FrameLayout) itemView.findViewById(R.id.background);
        mTextView = (TextView) itemView.findViewById(R.id.textView);
    }

    public void bind(ExampleModel model) {
        mBackground.setBackgroundColor(model.getColor());
        mTextView.setText(model.getText());
    }
}

As you can see nothing special, the Adapter implementation is equally simple:

public class ExampleAdapter extends RecyclerView.Adapter<ExampleViewHolder> {

    private final LayoutInflater mInflater;
    private final List<ExampleModel> mModels;

    public ExampleAdapter(Context context, List<ExampleModel> models) {
        mInflater = LayoutInflater.from(context);
        mModels = models;
    }

    @Override
    public ExampleViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        final View itemView = mInflater.inflate(R.layout.item_example, parent, false);
        return new ExampleViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(ExampleViewHolder holder, int position) {
        final ExampleModel model = mModels.get(position);
        holder.bind(model);
    }

    @Override
    public int getItemCount() {
        return mModels.size();
    }
}

And you use the whole thing like this:

final Random mRandom = new Random(System.currentTimeMillis());

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

    final List<ExampleModel> models = new ArrayList<>();
    for (int i = 0; i < 100; i++) {
        final int randomColor = generateRandomPastelColor();
        models.add(new ExampleModel(randomColor, String.valueOf(i)));
    }

    final ExampleAdapter adapter = new ExampleAdapter(getActivity(), models);
    recyclerView.setAdapter(adapter);
}

public int generateRandomPastelColor() {
    final int baseColor = Color.WHITE;

    final int red = (Color.red(baseColor) + mRandom.nextInt(256)) / 2;
    final int green = (Color.green(baseColor) + mRandom.nextInt(256)) / 2;
    final int blue = (Color.blue(baseColor) + mRandom.nextInt(256)) / 2;

    return Color.rgb(red, green, blue);
}

This should do what you are looking for and you can use it as an example of how to implement your Adapter.

I got the same problem ,when i used the radioButton in my listView row, I solved it. As in every scrolling the Cache is cleared, you have to store the changed data in every row. just check my code 

@Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
//      if(position==0)
//      Toast.makeText(context, ""+QuestionViewPageAdapter.mRadioGroupData, Toast.LENGTH_SHORT).show();

        final ViewHolder viewHolder;
        View row=convertView;

        radioButton=new RadioButton[Integer.parseInt(mNoOfCategoryGreading)];



            LayoutInflater inflater =LayoutInflater.from(context);//(LayoutInflater)context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
            row = inflater.inflate(R.layout.question_row, parent, false);

            viewHolder=new ViewHolder();

            viewHolder.tv_qContent=(TextView)row.findViewById(R.id.tv_question);
            viewHolder.rg=(RadioGroup)row.findViewById(R.id.rgrp);

            for(int i=0;i<Integer.parseInt(mNoOfCategoryGreading);i++)
            {
                radioButton[i]=new RadioButton(context);
                radioButton[i].setLayoutParams(new RadioGroup.LayoutParams(0, LayoutParams.WRAP_CONTENT,1f));
                //1f for layout_weight="1"
                radioButton[i].setId(i);
                radioButton[i].setText(""+(i+1));

                viewHolder.rg.addView(radioButton[i]);
            }
            row.setTag(viewHolder);


            for(int i=0;i<QuestionViewPageAdapter.mRadioGroupData.size();i++){
                int p=Integer.parseInt(""+QuestionViewPageAdapter.mRadioGroupData.get(i).get("position"));
                String id=QuestionViewPageAdapter.mRadioGroupData.get(i).get("Id");
                if(p!=-1 && id.equals(""+data.get(position).get(AppData.question_Set_category_QuestionID)))
                {//radioButton[p].setSelected(true);
                    viewHolder.rg.check(p-1);}
                //Toast.makeText(context, "Yes "+p, Toast.LENGTH_LONG).show();}
            }

        viewHolder.tv_qContent.setText((position+1)+". "+data.get(position).get(AppData.question_Set_category_QuestionContent));
        viewHolder.tv_qContent.setTypeface(typeface_muso_regular300);



        viewHolder.rg.setOnCheckedChangeListener(new OnCheckedChangeListener() {

            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                // TODO Auto-generated method stub

                String s=data.get(position).get(AppData.question_Set_category_QuestionID);
                isAvailabel(s);


                        int radioButtonID = viewHolder.rg.getCheckedRadioButtonId();
                        View radioButton = viewHolder.rg.findViewById(radioButtonID);
                        int idx = viewHolder.rg.indexOfChild(radioButton);
                        HashMap<String, String> map=new HashMap<String, String>();
                        map.put("position", ""+(idx+1));
                        map.put("Id", ""+data.get(position).get(AppData.question_Set_category_QuestionID));
                        map.put("CategoryId", ""+mCategoryId);
                        QuestionViewPageAdapter.mRadioGroupData.add(map);
                }


        });





        return row;
    }

    private void isAvailabel(String qId){

        for(int i=0;i<QuestionViewPageAdapter.mRadioGroupData.size();i++){
            if(qId.equals(QuestionViewPageAdapter.mRadioGroupData.get(i).get("Id"))){
                position=i;

                QuestionViewPageAdapter.mRadioGroupData.remove(i);
            }
        }

    }

     class ViewHolder {
         TextView tv_qContent ,tv_1,tv_2,tv_3;
            RadioGroup rg;
            RadioButton rBtn1,rBtn2,rBtn3,rBtn4,rBtn5;
     }

In my case overriding getItemId and setting sethasStableIds to true solved the shuffling issue.

in adapter:

    @Override
    public long getItemId(int position) {
    Object listItem = feeds.get(position);
    return listItem.hashCode();
    }

in main activity/fragment :

    adapter = new FeedAdapter(feeds, getContext());
    adapter.setHasStableIds(true);
标签
java
android
android-recyclerview
recycler-adapter
易学教程内所有资源均来自网络或用户发布的内容，如有违反法律规定的内容欢迎反馈！
该文章没有解决你所遇到的问题?点击提问,说说你的问题,让更多的人一起探讨吧!