我在viewpager片段中有一个listView。在列表视图中，我想在单击图像按钮时创建一个弹出菜单。这是我的代码：
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
final View myFragmentView = inflater.inflate(R.layout.songs, container, false);
nAdapter = new SongsAdapter(getActivity(), null);
setListAdapter(nAdapter);
final ImageButton ex_menu = (ImageButton) myFragmentView.findViewById(R.id.expanded_menu);
ex_menu.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//Creating the instance of PopupMenu
PopupMenu popup = new PopupMenu(getActivity().getApplicationContext(), ex_menu);
//Inflating the Popup using xml file
popup.getMenuInflater().inflate(R.menu.songitem_menu, popup.getMenu());
//registering popup with OnMenuItemClickListener
popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
public boolean onMenuItemClick(MenuItem item) {
switch (item.getItemId()) {
case R.id.one:
Log.i("ContextMenu", "Item 1a was chosen");
return true;
case R.id.two:
Log.i("ContextMenu", "Item 1b was chosen");
return true;
case R.id.three:
Log.i("ContextMenu", "Item 1b was chosen");
return true;
case R.id.four:
Log.i("ContextMenu", "Item 1b was chosen");
return true;
case R.id.five:
Log.i("ContextMenu", "Item 1b was chosen");
return true;
}
return true;
}
});
popup.show();//showing popup menu
}
});
return myFragmentView;
}
这是来自logcat
的错误消息java.lang.NullPointerException
at com.screens.Songs.onCreateView(Songs.java:52)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1789)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:955)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:740)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:490)
at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1072)
at android.support.v4.view.ViewPager.populate(ViewPager.java:918)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1440)
at android.view.View.measure(View.java:16838)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:926)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:607)
at android.view.View.measure(View.java:16838)
at android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:868)
at android.view.View.measure(View.java:16838)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5374)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:340)
at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:124)
at android.view.View.measure(View.java:16838)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5374)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1621)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:742)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:607)
at android.view.View.measure(View.java:16838)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5374)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:340)
at android.view.View.measure(View.java:16838)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5374)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1621)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:742)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:607)
at android.view.View.measure(View.java:16838)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5374)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:340)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2332)
at android.view.View.measure(View.java:16838)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2252)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1315)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1513)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1192)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6231)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:788)
at android.view.Choreographer.doCallbacks(Choreographer.java:591)
at android.view.Choreographer.doFrame(Choreographer.java:560)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:774)
at android.os.Handler.handleCallback(Handler.java:808)
at android.os.Handler.dispatchMessage(Handler.java:103)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5292)
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:824)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:640)
at dalvik.system.NativeStart.main(Native Method)
此外，我想知道如何从另一个弹出菜单创建一个弹出菜单。那是当我点击一个菜单的项目时，会出现另一个菜单。我该怎么做？
答案 0 :(得分：0)
从另一个弹出菜单中创建弹出菜单是一个更简单的概念。您在onMenuItemClickListener()方法中执行创建弹出窗口的相同过程。