对不起,如果这是一个微不足道的问题,但我不能解决它。我正在研究一个完整的应用程序,但我简化了这个问题:空指针异常开始另一个活动
我有三个活动(已在manifest中声明),我试图用“外部”方法启动一个。
活动1:
public void goNextActivity(View view){
Activity2 obj = new Activity2();
obj.jumpToThree(this);//I've already tried with getApplicationConext(), didn't work
}
活性2:
public void jumpToThree(Context context){
startActivity(new Intent(context, Activity3.class));
}
Activity3:
//empty standard activity that works normally
这是日志
FATAL EXCEPTION: main
Process: com.example.user.myapp, PID: 32408
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.internal.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:278)
at android.view.View.performClick(View.java:5201)
at android.view.View$PerformClick.run(View.java:21163)
at android.os.Handler.handleCallback(Handler.java:746)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5443)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.internal.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:273)
at android.view.View.performClick(View.java:5201)
at android.view.View$PerformClick.run(View.java:21163)
at android.os.Handler.handleCallback(Handler.java:746)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5443)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
****Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.app.ActivityThread$ApplicationThread android.app.ActivityThread.getApplicationThread()' on a null object reference
at android.app.Activity.startActivityForResult(Activity.java:3922)****
at android.app.Activity.startActivityForResult(Activity.java:3881)
at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:784)
at android.app.Activity.startActivity(Activity.java:4208)
at android.app.Activity.startActivity(Activity.java:4176)
****at com.example.user.myapp.folder.Activity2.jumpToThree(Activity2.java:91)****
****at com.example.user.myapp.MainActivity.goNextActivity(MainActivity.java:26)****
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.internal.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:273)
at android.view.View.performClick(View.java:5201)
at android.view.View$PerformClick.run(View.java:21163)
at android.os.Handler.handleCallback(Handler.java:746)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5443)
at java.lang.reflect.Method.invoke(Native Method)
你试图做的事绝对没有意义。如果你在activity1上,为什么不直接从Activity1启动一个Intent到Activity 2? – RafaelC
我正在做一个更大更复杂的应用程序,并解决这个简单的例子中的问题将帮助我@RafaelCardoso – user3891850
它仍然没有任何意义,因为行'startActivity(new Intent(context,Activity3.class));''最终成为'startActivity(new Intent(Activity1.this,Activity3.class));'。在Activity2上调用这个'startActivity'没有任何意义! – RafaelC