Android 如何在片段中实现 onBackPressed() 和意图？
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How to implement onBackPressed() & intents in fragment?
提问by addy123
I know that onBackPressed() is a method in activity but, I want to use the functionality in fragments such that when back button is pressed, it gets redirected to another activity via Intent. Is there any solution to this ?
我知道 onBackPressed() 是活动中的一种方法，但是，我想在片段中使用该功能，以便在按下后退按钮时，它会通过 Intent 重定向到另一个活动。有什么解决办法吗？
public class News_Events_fragment extends Fragment {
ProgressDialog pd;
ListView lv1;
SharedPreferences sharedPreferences = null;
int NotiCount;
TextView txt_title, txt_msg, textView;
Context context;
Intent intent ;
ArrayList<SliderMsgTitleModel> CurrentOfficersPastList;
NewsActivityAdapter pastAdapter;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
context = (Context) getActivity();
View rootView = inflater.inflate(R.layout.activity_news, container, false);
new AsyncTask<Void, Void, ArrayList<SliderMsgTitleModel>>() {
protected void onPreExecute() {
pd = new ProgressDialog(getActivity());
pd.setCancelable(true);
pd.setTitle("UPOA");
pd.setMessage("Please wait,loading the data...");
pd.show();
}
@Override
protected ArrayList<SliderMsgTitleModel> doInBackground(
Void... params) {
System.out.println("In Background");
CurrentOfficersPastList = new ArrayList<SliderMsgTitleModel>();
// display view for selected nav drawer item
ParseQuery<ParseObject> query = ParseQuery.getQuery("message");
query.whereEqualTo("featured_status", true);
// query.whereEqualTo("push_status", true);
query.orderByDescending("updatedAt");
query.selectKeys(Arrays.asList("title"));
query.selectKeys(Arrays.asList("message"));
try {
query.setCachePolicy(ParseQuery.CachePolicy.NETWORK_ELSE_CACHE);
List<ParseObject> results = query.find();
for (int i = 0; i < results.size(); i++) {
ParseObject object = results.get(i);
CurrentOfficersPastList.add(new SliderMsgTitleModel(
object.getString("title"), object
.getString("message")));
System.out.println("title is=="
+ object.getString("title") + "&& message is"
+ object.getString("message") + "size is"
+ CurrentOfficersPastList.size());
}
} catch (Exception e) {
e.getMessage();
}
pd.dismiss();
return CurrentOfficersPastList;
}
@SuppressWarnings("unchecked")
@Override
protected void onPostExecute(ArrayList<SliderMsgTitleModel> value) {
pd.dismiss();
/*Intent ent = new Intent(getActivity(), NewsActivity.class);
ent.putExtra("NEWSLIST", (ArrayList<SliderMsgTitleModel>) value);
startActivity(ent);
System.out.println("Value is" + value.size());*/
CurrentOfficersPastList = new ArrayList<SliderMsgTitleModel>();
CurrentOfficersPastList = value;
lv1 = (ListView) getActivity().findViewById(R.id.list_title);
pastAdapter = new NewsActivityAdapter(getActivity(), R.layout.activity_news_txt, CurrentOfficersPastList);
lv1.setAdapter(pastAdapter);
}
}.execute();
return rootView;
}
public void onBackPressed() {
// TODO Auto-generated method stub
//super.onBackPressed();
//Toast.makeText(getApplicationContext(), "click",2000).show();
String cameback="CameBack";
intent = new Intent(getActivity(),HomeActivity.class);
intent.putExtra("Comingback", cameback);
startActivity(intent);
}
}
采纳答案by Alok Kulkarni
Override onKeyDown instead of onBackPressed. Not necessarily . But this works for me
覆盖 onKeyDown 而不是 onBackPressed。不必要 。但这对我有用
public boolean onKeyDown(int keyCode, KeyEvent event) {
switch (keyCode) {
case KeyEvent.KEYCODE_BACK:
String cameback="CameBack";
intent = new Intent(getActivity(),HomeActivity.class);
intent.putExtra("Comingback", cameback);
startActivity(intent);
return true
}
return false;
}
回答by sirFunkenstine
You can interact with the fragment using a callback interface. In your activity add the following:
您可以使用回调接口与片段交互。在您的活动中添加以下内容：
public class MyActivity extends Activity {
protected OnBackPressedListener onBackPressedListener;
public interface OnBackPressedListener {
void doBack();
}
public void setOnBackPressedListener(OnBackPressedListener onBackPressedListener) {
this.onBackPressedListener = onBackPressedListener;
}
@Override
public void onBackPressed() {
if (onBackPressedListener != null)
onBackPressedListener.doBack();
else
super.onBackPressed();
}
@Override
protected void onDestroy() {
onBackPressedListener = null;
super.onDestroy();
}
}
In your fragment add the following:
在您的片段中添加以下内容：
public class MyFragment extends Fragment implements MyActivity.OnBackPressedListener {
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
((MyActivity) getActivity()).setOnBackPressedListener(this);
}
@Override
public void doBack() {
//BackPressed in activity will call this;
}
}
回答by Chintan Rathod
Yes, There is. You should implement like this.
就在这里。你应该像这样实施。
@Override
public void onBackPressed() {
if (fragment != null)
//user defined onBackPressed method. Not of Fragment.
fragment.onBackPressed();
} else {
//this will pass BackPress event to activity. If not called, it will
//prevent activity to get BackPress event.
super.onBackPressed();
}
}
Explanation
解释
- Check whether your fragment is initialized or not. If it is, then pass on back press event to your fragment.
- If above condition not passed, just pass back press to your activity so that it will handle it.
- 检查您的片段是否已初始化。如果是，则将返回按下事件传递给您的片段。
- 如果上述条件未通过，只需将按下返回到您的活动，以便它处理它。
Note
笔记
Here condition can be anything. I just take fragmentinitialization as an example. May be that can't be helped you. You need to define your own condition to pass it to fragment.
这里条件可以是任何东西。我只是以fragment初始化为例。可能帮不了你。您需要定义自己的条件以将其传递给片段。
Edit
编辑
I created a sample application on GitHub to implement Back Stack of fragment .
我在 GitHub 上创建了一个示例应用程序来实现 Fragment 的 Back Stack。
Download Fragment Back Stackapplication.
下载片段返回堆栈应用程序。
回答by Priya
You can implement onKeyListener for your fragment and call next activity within that. I've never tried this. But i hope it may help
您可以为片段实现 onKeyListener 并在其中调用下一个活动。我从来没有试过这个。但我希望它可以帮助
For Example
例如
fragmentObject.getView().setOnKeyListener( new OnKeyListener()
{
@Override
public boolean onKey( View v, int keyCode, KeyEvent event )
{
if( keyCode == KeyEvent.KEYCODE_BACK )
{
//your code here
}
return false;
}
} );
回答by Shrikant Salunkhe
You need to override onBackPressed method in fragment.
您需要在片段中覆盖 onBackPressed 方法。
