Show DialogFragment when user clicks deny on Runtime permissions dialog

问题

I'm trying to show a DialogFragment right after the user clicks "Deny" on the "allow/deny permission" dialog of android 6 But instead I'm getting this error:

    Caused by: java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState
  at android.support.v4.app.FragmentManagerImpl.checkStateLoss(FragmentManager.java:1448)
  at android.support.v4.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1466)
  at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:634)
  at android.support.v4.app.BackStackRecord.commit(BackStackRecord.java:613)
  at android.support.v4.app.DialogFragment.show(DialogFragment.java:139)
  at android.support.v4.app.FragmentActivity.onRequestPermissionsResult(FragmentActivity.java:802)
  at android.app.Activity.dispatchRequestPermissionsResult(Activity.java:6553)
  at android.app.Activity.dispatchActivityResult(Activity.java:6432)
  at android.app.ActivityThread.deliverResults(ActivityThread.java:3695)
  at android.app.ActivityThread.handleSendResult(ActivityThread.java:3742) 
  at android.app.ActivityThread.-wrap16(ActivityThread.java) 
  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1393) 
  at android.os.Handler.dispatchMessage(Handler.java:102) 
  at android.os.Looper.loop(Looper.java:148) 
  at android.app.ActivityThread.main(ActivityThread.java:5417) 
  at java.lang.reflect.Method.invoke(Native Method) 
  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

My dialog code is pretty standard

  protected void showDialog(DialogFragment diag)
    {
        if (diag != null && !diag.isAdded())
            diag.show(getSupportFragmentManager(), "dialog");
    }

How can this be fixed?

回答1:

So, there are a couple of solutions to this, none particularly pretty. What it means is that your Activity's FragmentManager is not yet in a valid state for committing FragmentTransactions in a safe manner (although in this particular case, it should always be.)

1) Use .commitAllowingStateLoss() instead of .show():

This is the easiest fix, although I'm not entirely clear what differences arise by not using the .show() methods, which set a few flags internally. Seems to work fine.

getSupportFragmentManager()
        .beginTransaction()
        .add(diag, "dialog")
        .commitAllowingStateLoss();

1) Post the .show() as a Runnable on a Handler:

// Initialize a Handler ahead of time and keep it around
private Handler mHandler = new Handler();

...

// after getting denied:
mHandler.post(new Runnable() {
    @Override
    public void run() {
        // Show your dialog
    }
}

...

@Override
protected void onStop() {
    super.onStop();

    // Clear out the Runnable for an unlikely edge case where your
    // Activity goes to stopped state before the Runnable executes
    mHandler.removeCallbacksAndMessages(null);
}

2) Set a flag and show the dialog in onResume()

private boolean mPermissionDenied;

@Override
public void onRequestPermissionsResult(...) {
    // If denied...
    mPermissionDenied = true;   
}

@Override
protected void onResume() {
    super.onResume();

    if (mPermissionDenied) {
        mPermissionDenied = false;
        // Show your dialog
    }
}

回答2:

I will also like to add something I just discovered. If I switch the getSupportFragmentManager() on my existing code with getSupportFragmentManager().beginTransaction() it works fine. Code below

   protected void showDialog(final DialogFragment diag)
    {
        cancelDialog();
        if (diag != null && !diag.isAdded())
            diag.show(getSupportFragmentManager().beginTransaction(), "dialog");
    }

No idea why this works as I want to.

回答3:

Showing a dialog after the user click on deny is not what guidelines said. You should show the permission rational only before a second request. You can look here for an automatic management: Permission library

来源：https://stackoverflow.com/questions/33181952/show-dialogfragment-when-user-clicks-deny-on-runtime-permissions-dialog