当打算显示对话框时，App Force关闭

Question

I've been trying to using an AlertDialog to open when the user does not have GPS enabled and direct them to the Settings.ACIOTN_LOCATION_SOURCE_SETTINGS using an intent.

    private void buildAlertDialog() 
{
    // TODO Auto-generated method stub
    AlertDialog.Builder builder = new AlertDialog.Builder(getApplicationContext());
    builder.setMessage("Gps is disabled, do you want to enable it?");
    builder.setCancelable(false);
    builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {

        @Override
        public void onClick(DialogInterface dialog, int id) 
        {
            // TODO Auto-generated method stub
            startActivity(new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS));

        }
    });

    builder.setNegativeButton("No", new DialogInterface.OnClickListener() {

        @Override
        public void onClick(DialogInterface dialog, int id) {
            // TODO Auto-generated method stub
            dialog.cancel();
        }
    });
    AlertDialog alert = builder.create();
    alert.show();
}

The buildAlertDialog() is called when the user enters this activity and GSP is not enabled it is called by this snippet of code

mLocManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
    if(!mLocManager.isProviderEnabled(LocationManager.GPS_PROVIDER))
    {
        buildAlertDialog();
    }
    mLocListener = new LocListener();
    mLocManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, mLocListener);

The Logcat output of the error is as follows

 FATAL EXCEPTION: main
 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.fyp.run_race/com.fyp.run_race.Begin_Run}: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2781)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2797)
at android.app.ActivityThread.access$2300(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2132)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:143)
at android.app.ActivityThread.main(ActivityThread.java:4914)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
at dalvik.system.NativeStart.main(Native Method)
 Caused by: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
at android.view.ViewRoot.setView(ViewRoot.java:513)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:177)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
at android.app.Dialog.show(Dialog.java:241)
at com.fyp.run_race.Begin_Run.buildAlertDialog(Begin_Run.java:133)
at com.fyp.run_race.Begin_Run.onCreate(Begin_Run.java:82)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1065)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2745)
... 11 more

I thought it might be that the new activity is not registered with the android manifest file of the application

Answer 1

There may be a problem with the getApplicationContext() line, check this thread

You should pass an Activity reference to the builderAlertDialog() it would be this if the method is called from an Activity class.