问题
I have three fragments, the second and the third one, have a listView in their respective layout.
initially, the listView of both "second and third Frament", is populated with the same items. i other words, initially the the listView of the second fragment and the third one, contain the following where CB: is checkBox and IV: is ImageView and t is: textview, and SaveButton is a buton
t1........CB.......IV
t2........CB.......IV
t3........CB.......IV
t4........CB.......IV
t5........CB.......IV
t6........CB.......IV
SaveButton
what i am trying to do is, while i am in the second fragment and selected an item(s) from the listView "using the checkbox" and clicked "Save" button, then, that item i selected, should be deleted from the listView in the third Fragment.
to achieve this,in getview(), i checked if the the checkBox is checked from the the listView of the second fragment, and if it is checked, i add the checked items to a list. as shown in getView():
Second Fragment:
private void setUpListView() {
// TODO Auto-generated method stub
this.topicsList = new ArrayList<String>();
for (int i = 0; i < this.topics.length; i++) {
this.topicsList.add(topics[i]);
}
this.adapter = new ListViewAdapter(getActivity(), this.topicsList, ECO_FRAG_ID);
this.listView.setAdapter(adapter);
}
Third Fragment:
private void setUpListView() {
// TODO Auto-generated method stub
this.topicsList = new ArrayList<String>();
for (int i = 0; i < this.topics.length; i++) {
this.topicsList.add(topics[i]);
}
this.adapter = new ListViewAdapter(getActivity(), this.topicsList, LOGGER_FRAG_ID);
this.listView.setAdapter(adapter);
}
BaseAdapter:
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
if (convertView == null) {
LayoutInflater layoutinflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
convertView = layoutinflater.inflate(R.layout.list_items_layout, null);
}
if (this.checkedItemsList1 == null) {
this.checkedItemsList1 = new ArrayList<String>();
}
if (this.checkedItemsList2 == null) {
this.checkedItemsList2 = new ArrayList<String>();
}
final TextView tv = (TextView) convertView.findViewById(R.id.tvlist_topic);
final CheckBox cb = (CheckBox) convertView.findViewById(R.id.cbList_hook);
final ImageView iv = (ImageView) convertView.findViewById(R.id.ivList_delete);
tv.setText(this.topicsList.get(position));
if (cb.isChecked() && (this.id == 1) ) {
this.checkedItemsList1.add(this.topicsList.get(position));
this.setCheckedItemsList1(this.checkedItemsList1);
}
if (cb.isChecked() && (this.id == 2) ) {
this.checkedItemsList2.add(this.topicsList.get(position));
this.setCheckedItemsList2(this.checkedItemsList2);
}
iv.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (cb.isChecked())
cb.setChecked(false);
topicsList.remove(position);
notifyDataSetChanged();
}
});
return convertView;
}
And i created an interface, which is initialised in onAttach() and called when i click the savebuton in the secondFragment as folows:
private OnClickListener btnSaveListener = new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Toast.makeText(getActivity(), "Save to SQLite", Toast.LENGTH_SHORT).show();
Log.d(TAG, "size: " + adapter.getCheckedItemsList1().size());
iCSC.onCheckedStateChanged(adapter.checkedItemsList1, ECO_FRAG_ID);
}
};
this inerface, the mainActivity implements it, and in the implemntation of the interface, i pass the list f the checked items from the second Fragment to the third Fragment through a public method in the third fragmet that updates the list and then assign the list to the adapter, as follows:
@Override
public void onCheckedStateChanged(ArrayList<String> list, int id) {
// TODO Auto-generated method stub
switch (id) {
case 1:
((Logger_Settings_Frag) this.fragList.get(2)).updateTopicList(list);
break;
case 2:
break;
}
}
**updateTopicList in the third fragment**
public void updateTopicList(ArrayList<String> list) {
for (String str : list) {
this.topicsList.remove(str);
}
this.adapter = new ListViewAdapter(getActivity(), this.topicsList, LOGGER_FRAG_ID);
this.listView.setAdapter(adapter);
}
updateTopicList in the third fragment
public void updateTopicList(ArrayList<String> list) {
for (String str : list) {
this.topicsList.remove(str);
}
this.adapter = new ListViewAdapter(getActivity(), this.topicsList, LOGGER_FRAG_ID);
this.listView.setAdapter(adapter);
}
when i run that code, in the saveButton listener of the second fragment, the log.d message displays that the size of the list that should contain the items that was checked, is zero size?!
please have a look at the code and let me know what i am missing?
回答1:
try this: Its a sample Project OneActivity with two Fragments: public ArrayList myBeansList_frgnt1; public ArrayList myBeansList_frgnt2; by clicking the save button iterate the myBeansList_frgnt1 and checking the condition that any item is selected or not. if item is selected i am adding that item to myBeansList_frgnt2 .showing in fragment2.
MainActivity:
public class MainActivity extends FragmentActivity {
private FragmentManager mFragmentManager;
private MyFragment1 myFragment1;
public ArrayList<MyBean> myBeansList_frgnt1;
public ArrayList<MyBean> myBeansList_frgnt2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mFragmentManager = getSupportFragmentManager();
myBeansList_frgnt1 = new ArrayList<MyBean>();
myBeansList_frgnt2 = new ArrayList<MyBean>();
}
@Override
protected void onResume() {
super.onResume();
myFragment1 = new MyFragment1();
FragmentTransaction mTransaction = mFragmentManager.beginTransaction();
mTransaction.replace(R.id.framid, myFragment1, "applock").commit();
}
}
MyBaseAdpter: maintaining the states in the MyBean object
@Override
public View getView(int position, View view, ViewGroup parent) {
final ViewHolder holder;
if (view == null) {
holder = new ViewHolder();
view = LayoutInflater.from(mContext).inflate(R.layout.list_item, null);
holder.mTextView = (TextView) view.findViewById(R.id.textView1);
holder.mBox = (CheckBox) view.findViewById(R.id.checkBox1);
holder.mImageView = (ImageView) view.findViewById(R.id.imageView1);
view.setTag(holder);
} else {
holder = (ViewHolder) view.getTag();
}
final MyBean mBean = mBeansList.get(position);
holder.mBox.setOnCheckedChangeListener(null);
holder.mBox.setChecked(mBean.isChecked());
holder.mBox.setOnCheckedChangeListener(new OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (isChecked) {
mBean.setChecked(true);
} else {
mBean.setChecked(false);
}
}
});
// setting text and image
holder.mTextView.setText(mBean.getmName());
holder.mImageView.setImageResource(mBean.getmImgId());
return view;
}
private class ViewHolder {
TextView mTextView;
CheckBox mBox;
ImageView mImageView;
}
Fragment1:
public class MyFragment1 extends Fragment {
private ListView mListView;
private MyBaseAdpter myBaseAdpter;
private Button mButton;
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_layout, null);
mListView = (ListView) view.findViewById(R.id.listviewid);
mButton = (Button) view.findViewById(R.id.bttnid);
return view;
}
@Override
public void onResume() {
super.onResume();
final MainActivity mActivity = (MainActivity) getActivity();
myBaseAdpter = new MyBaseAdpter(mActivity.myBeansList_frgnt1, getActivity());
mListView.setAdapter(myBaseAdpter);
mButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
int size = mActivity.myBeansList_frgnt1.size();
for (int i = 0; i < size; i++) {
MyBean mMyBean = mActivity.myBeansList_frgnt1.get(i);
if (mMyBean.isChecked()) {
mActivity.myBeansList_frgnt2.add(mMyBean);
}
}
}
});
}
}
Fragment2:
public class MyFragment2 extends Fragment {
private ListView mListView;
private MyBaseAdpter myBaseAdpter;
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_layout, null);
mListView = (ListView) view.findViewById(R.id.listviewid);
return view;
}
@Override
public void onResume() {
super.onResume();
MainActivity mActivity = (MainActivity) getActivity();
myBaseAdpter = new MyBaseAdpter(mActivity.myBeansList_frgnt2, getActivity());
mListView.setAdapter(myBaseAdpter);
}
}
MyBean:
public class MyBean {
private String mName;
private int mImgId;
private boolean isChecked;
public String getmName() {
return mName;
}
public void setmName(String mName) {
this.mName = mName;
}
public int getmImgId() {
return mImgId;
}
public void setmImgId(int mImgId) {
this.mImgId = mImgId;
}
public boolean isChecked() {
return isChecked;
}
public void setChecked(boolean isChecked) {
this.isChecked = isChecked;
}
public MyBean() {
super();
// TODO Auto-generated constructor stub
}
}
来源：https://stackoverflow.com/questions/28275273/how-to-update-listview-contents-between-fragments-through-the-main-activity