Accessing FragmentManager in a custom view class

问题

In my custom view I have a Java class running a simple game. When the game is finished I'd like to display my DialogFragment, but the getFragmentManager() method seems to be undefined.

FragmentManager manager = getFragmentManager();
Finish finish = new Finish();
finish.show(manager, "done");

I've tried getting the manager through a Fragment obj as:

Fragment fragment = new Fragment();
FragmentManager manager = fragment.getFragmentManager();

But that returns as null. I know it's a new Fragment instance, but I'm not sure what value to give it. Any help would be much appreciated.

回答1:

if your view is attached to an Activity then simply you can do

((Activity)getContext()).getFragmentManager();

((ActivityCompat)getContext()).getSupportFragmentManager();

and to be more safe please make sure you check against of the View Context is instance of an Activity by doing such:

if(getContext() instanceof Activity)// do something

and a better solution is, i had rely on a callback between the View and the Activity.

回答2:

I use that simple helper method:

fun getFragmentManager(context: Context?): FragmentManager? {
    return when (context) {
        is AppCompatActivity -> context.supportFragmentManager
        is ContextThemeWrapper -> getFragmentManager(context.baseContext)
        else -> null
    }
}

回答3:

You can use this (in Kotlin):

if ((context as ContextThemeWrapper).baseContext is AppCompatActivity) {
            //View is attached to an AppCompatActivity
        } else {
            //View is not attached to an AppCompatActivity
        }
}

回答4:

For AndroidX, you can try:

ContextThemeWrapper themeWrapper = (ContextThemeWrapper) getContext();
FragmentManager fm = ((AppCompatActivity) themeWrapper.getBaseContext()).getSupportFragmentManager();

As recommoned by @k0sh, instaceof safety check is recommonded.

来源：https://stackoverflow.com/questions/36684553/accessing-fragmentmanager-in-a-custom-view-class

标签

java

android

android-fragments