我向我的项目添加了一个底部导航活动,但是当我启动相关活动时,它给出了空指针异常。
它说异常是在第 28 行触发的
在 lk.apiit.eea.mobile.Activities.CompanyProfile.onCreate(CompanyProfile.java:28)
以下是异常和代码
请帮我解决这个问题..谢谢
java.lang.RuntimeException: Unable to start activity ComponentInfo{lk.apiit.eea.mobile/lk.apiit.eea.mobile.Activities.CompanyProfile}: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.appcompat.app.ActionBar.setTitle(java.lang.CharSequence)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2720)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2781)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1508)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:241)
at android.app.ActivityThread.main(ActivityThread.java:6274)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.appcompat.app.ActionBar.setTitle(java.lang.CharSequence)' on a null object reference
at androidx.navigation.ui.ActionBarOnDestinationChangedListener.setTitle(ActionBarOnDestinationChangedListener.java:48)
at androidx.navigation.ui.AbstractAppBarOnDestinationChangedListener.onDestinationChanged(AbstractAppBarOnDestinationChangedListener.java:100)
at androidx.navigation.NavController.addOnDestinationChangedListener(NavController.java:218)
at androidx.navigation.ui.NavigationUI.setupActionBarWithNavController(NavigationUI.java:220)
at lk.apiit.eea.mobile.Activities.CompanyProfile.onCreate(CompanyProfile.java:28)
at android.app.Activity.performCreate(Activity.java:6720)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2673)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2781)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1508)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:241)
at android.app.ActivityThread.main(ActivityThread.java:6274)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
这是 onCreateMethod 中的代码
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_company_profile);
BottomNavigationView navView = findViewById(R.id.nav_view);
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
AppBarConfiguration appBarConfiguration = new AppBarConfiguration.Builder(
R.id.navigation_home, R.id.navigation_dashboard, R.id.navigation_notifications)
.build();
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration);
NavigationUI.setupWithNavController(navView, navController);
}
如果你没有打电话setSupportActionBar()
你正在使用一个NoActionBar
主题,那么你就没有 ActionBar。setupActionBarWithNavController()
假设您有一个 ActionBar,因此会出现 NullPointerException。
您应该切换到提供 ActionBar 或调用的主题setSupportActionBar()
with a Toolbar
在调用之前在您的布局中setupActionBarWithNavController()
.
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