меню андроид изменение текста - PullRequest
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меню андроид изменение текста

1 голос
/ 22 декабря 2019

Я пытаюсь изменить заголовок меню при запуске приложения в зависимости от того, зарегистрирован пользователь или нет, но я получаю эту ошибку: 

Process: com.cloud.services, PID: 25186
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.cloud.services/com.cloud.services.MainActivity}: 
    java.lang.NullPointerException: Attempt to invoke interface method 'android.view.MenuItem android.view.Menu.findItem(int)' on a null object reference
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2345)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2405)
    at android.app.ActivityThread.access$800(ActivityThread.java:149)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1324)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:211)
    at android.app.ActivityThread.main(ActivityThread.java:5315)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:941)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:736)
 Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'android.view.MenuItem android.view.Menu.findItem(int)' on a null object reference
    at com.cloud.services.MainActivity.onCreate(MainActivity.java:35)
    at android.app.Activity.performCreate(Activity.java:5933)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2405) 
    at android.app.ActivityThread.access$800(ActivityThread.java:149) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1324) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:211) 
    at android.app.ActivityThread.main(ActivityThread.java:5315) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:372) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:941) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:736)

Мой код MainActivity: 

public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";

private SectionsPageAdapter mSectionsPageAdapter;
private FirebaseAuth auth;
private Menu menu;
private ViewPager mViewPager;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


    auth = FirebaseAuth.getInstance();

    if (auth.getCurrentUser() != null) {
        MenuItem item= menu.findItem(R.id.action_settings);
        item.setTitle("LogOut");
    }


    setContentView(R.layout.activity_main);


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.loginmenu, menu);
    return true;
}
//and this to handle actions
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        if (item.getTitle().equals("Login\SignUp**strong text**")){
        Intent intent4 = new Intent(MainActivity.this, LoginActivity.class);
        startActivity(intent4);}
        else{
            auth.signOut();
        }
        return true;
    }
    return super.onOptionsItemSelected(item);
}

}
...