我在Android工作室工作，一切正常，但突然出现问题。当我单击右上方的选项菜单按钮时，菜单不会膨胀并且应用程序崩溃，菜单项在设置为app:showAsAction="always"时工作正常但在app:showAsAction="never"时崩溃。此外，当我重建我之前的项目来检查问题时，他们也遇到了这个问题，而这个问题以前就不存在了。
MainActivity.java
public class MainActivity extends AppCompatActivity {
Toolbar toolbare;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.drawer_activity);
toolbare = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbare);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_menu_white_24dp);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
super.onCreateOptionsMenu(menu);
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_list_view_type, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
Log.i("info", "In optionsItemSelected");
switch (item.getItemId()) {
case R.id.view_type_single:
NoteFragSingle noteSingle = new NoteFragSingle();
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.setCustomAnimations(android.R.anim.fade_in,
android.R.anim.fade_out);
fragmentTransaction.replace(R.id.fragMent, noteSingle);
fragmentTransaction.commitAllowingStateLoss();
return true;
case R.id.view_type_multi:
NoteFragGrid noteFragGrid = new NoteFragGrid();
fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.setCustomAnimations(android.R.anim.fade_in,
android.R.anim.fade_out);
fragmentTransaction.replace(R.id.fragMent, noteFragGrid);
fragmentTransaction.commitAllowingStateLoss();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
menu_list_view_type.xml
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<item
android:id="@+id/view_type_multi"
android:icon="@drawable/ic_view_module_black_24dp"
android:title="Multi Column View"
app:showAsAction="never" />
<item
android:id="@+id/view_type_single"
android:icon="@drawable/ic_view_list_black_24dp"
android:title="Single Column View"
app:showAsAction="never" />
</menu>
应用级 build.gradle
// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
repositories {
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:2.3.3'
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}
allprojects {
repositories {
jcenter()
}
}
task clean(type: Delete) {
delete rootProject.buildDir
}
此错误每次出现在当前以及之前正常工作的每个项目中。
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at android.support.v7.view.menu.ListMenuItemView.setTitle(ListMenuItemView.java:127)
at android.support.v7.view.menu.ListMenuItemView.initialize(ListMenuItemView.java:113)
at android.support.v7.view.menu.MenuAdapter.getView(MenuAdapter.java:100)
at android.support.v7.view.menu.MenuPopup.measureIndividualMenuWidth(MenuPopup.java:160)
at android.support.v7.view.menu.StandardMenuPopup.tryShow(StandardMenuPopup.java:153)
at android.support.v7.view.menu.StandardMenuPopup.show(StandardMenuPopup.java:187)
at android.support.v7.view.menu.MenuPopupHelper.showPopup(MenuPopupHelper.java:290)
at android.support.v7.view.menu.MenuPopupHelper.tryShow(MenuPopupHelper.java:175)
at android.support.v7.widget.ActionMenuPresenter$OpenOverflowRunnable.run(ActionMenuPresenter.java:803)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:7325)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
我试过干净并重建，无效并重新启动但没有任何效果请帮助我。
的修改
这是片段代码
public class NoteFragSingle extends Fragment {
private NoteAdapter mAdapter;
RecyclerView rView;
SQLiteDatabase db;
Cursor cursor;
RecyclerView.LayoutManager mLayoutManager;
private List<Note> noteList = new ArrayList<Note>();
public NoteFragSingle() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v= inflater.inflate(R.layout.fragment_note_frag_single, container, false);
rView = (RecyclerView) v.findViewById(R.id.recycler_view);
TextView empty = (TextView) v.findViewById(R.id.empty_single);
mAdapter = new NoteAdapter(getActivity(), noteList);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getActivity());
rView.setLayoutManager(mLayoutManager);
rView.setItemAnimator(new DefaultItemAnimator());
rView.setAdapter(mAdapter);
/* if(noteList.isEmpty()){
rView.setVisibility(View.GONE);
empty.setVisibility(View.VISIBLE);
}
else {
rView.setVisibility(View.VISIBLE);
empty.setVisibility(View.GONE);
}
*/
try {
Databasehelper textoDatabaseHelper = new Databasehelper(getActivity());
db = textoDatabaseHelper.getReadableDatabase();
cursor = db.query("NOTES", new String[]{"_id","TITLE", "DESCRIPTION", "DATE"}, null, null, null, null, null);
if (cursor.moveToFirst()){
do {
String Title = cursor.getString(1);
String Description = cursor.getString(2);
String Date = cursor.getString(3);
Note note = new Note(Title, Description, Date);
noteList.add(note);
mAdapter.notifyDataSetChanged();
}while(cursor.moveToNext());
}
} catch (SQLiteException e) {
Toast.makeText(getActivity(),"Cannot retrieve notes. Try again", Toast.LENGTH_SHORT).show();
}
return v;
}
}
答案 0 :(得分：0)
你在错误的点上称通货膨胀。您应该在致电 super（）之前执行此操作。如下所示。
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu
getMenuInflater().inflate(R.menu.menu_list_view_type, menu);
return super.onCreateOptionsMenu(menu);;
}