如何销毁Backstack上的片段？

Question

I am trying to implement a method where I want to return to the previous fragment and destroy the current one. However, when I add the fragment to the Backstack it doesn't get destroyed anymore afterwards.

Is there any way to destroy it? Or maybe to return to the previous fragment without using the Backstack?

Edit: I want to use the backwards navigation as well.

Answer 1

Firstly if you are using the BackStack, it is not typical to need to specifically manually remove Fragments, which suggests you might want to have another think about your design.

That said, to specifically manually remove a Fragment, Override onBackPressed in your Activity which is showing the Fragments, manually remove the Fragment there.

To make it easy to determine which Fragment is currently showing, you can give it a Tag when you show it. For example:

fragTrans.replace(android.R.id.content, myFragment, "MY_FRAGMENT_X");

Then in the onBackPressed function of your Activity

@Override
public void onBackPressed() 
{

    FragmentManager fragMan = getFragmentManager();

    // Check if that Fragment is currently visible
    MyFragment myFragment = (MyFragment)fragMan.findFragmentByTag("MY_FRAGMENT_X");
    boolean myFragXwasVisible = myFragment.isVisible();

    // Let the Activity pop the BackStack as normal
    super.onBackPressed();

    // If it was your particular Fragment that was visible...
    if (myFragXwasVisible) 
    {
        FragmentTransaction trans = fragMan.beginTransaction();
        trans.remove(myFragment).commit();
    }
}

Note: When it comes to specifically destroying your Fragment object, that is what Java's garbage collection is for. You don't need to worry about that yourself, Java will take care of destroying it when it needs to. That's the whole point.