Android Fragment handle back button press [duplicate]

Answer 1

For Those Who Use Static Fragment

In a case if you have a static fragment then It would be preferable. Make an instance object of your fragment

private static MyFragment instance=null;

in onCreate() of MyFragment initialize that instance

  instance=this;

also make a function to get Instance

 public static MyFragment getInstance(){
   return instance;
}

also make functions

public boolean allowBackPressed(){
    if(allowBack==true){
        return true;
    }
    return false;
}


 //allowBack is a boolean variable that will be set to true at the action 
 //where you want that your backButton should not close activity. In my case I open 
 //Navigation Drawer then I set it to true. so when I press backbutton my 
 //drawer should be get closed

public void performSomeAction(){
    //.. Your code
    ///Here I have closed my drawer
}

In Your Activity You can do

@Override
public void onBackPressed() {

    if (MyFragment.getInstance().allowBackPressed()) { 
        MyFragment.getInstance().performSomeAction();
    }
    else{
        super.onBackPressed();
    }
}

Answer 2

Add this code in your Activity

@Override

public void onBackPressed() {
    if (getFragmentManager().getBackStackEntryCount() == 0) {
        super.onBackPressed();
    } else {
        getFragmentManager().popBackStack();
    }
}

And add this line in your Fragment before commit()

ft.addToBackStack("Any name");

Answer 3

I'm working with SlidingMenu and Fragment, present my case here and hope helps somebody.

Logic when [Back] key pressed :

1. When SlidingMenu shows, close it, no more things to do.
2. Or when 2nd(or more) Fragment showing, slide back to previous Fragment, and no more things to do.

3. SlidingMenu not shows, current Fragment is #0, do the original [Back] key does.

   public class Main extends SherlockFragmentActivity
   {
     private SlidingMenu menu=null;
     Constants.VP=new ViewPager(this);
   
     //Some stuff...
   
     @Override
     public void onBackPressed()
     {
       if(menu.isMenuShowing())
       {
         menu.showContent(true); //Close SlidingMenu when menu showing
         return;
       }
       else
       {
         int page=Constants.VP.getCurrentItem();
         if(page>0)
         {
           Constants.VP.setCurrentItem(page-1, true); //Show previous fragment until Fragment#0
           return;
         }
         else
         {super.onBackPressed();} //If SlidingMenu is not showing and current Fragment is #0, do the original [Back] key does. In my case is exit from APP
       }
     }
   }
   

Answer 4

The most ideal way of doing this is found here: Fragment: which callback invoked when press back button & customize it

public class MyActivity extends Activity
{
    //...
    //Defined in Activity class, so override
    @Override
    public void onBackPressed()
    {
        super.onBackPressed();
        myFragment.onBackPressed();
    }
}

public class MyFragment extends Fragment
{
    //Your created method
    public static void onBackPressed()
    {
        //Pop Fragments off backstack and do your other checks
    }
}

Answer 5

We created tiny library for handling back press across multiple fragments and/or in Activity. Usage is as simple as adding dependency in your gradle file:

compile 'net.skoumal.fragmentback:fragment-back:0.1.0'

Let your fragment implement BackFragment interface:

public abstract class MyFragment extends Fragment implements BackFragment {

    public boolean onBackPressed() {

        // -- your code --

        // return true if you want to consume back-pressed event
        return false;
    }

    public int getBackPriority() {
        return NORMAL_BACK_PRIORITY;
    }
}

Notify your fragments about back presses:

public class MainActivity extends AppCompatActivity {

    @Override
    public void onBackPressed() {
        // first ask your fragments to handle back-pressed event
        if(!BackFragmentHelper.fireOnBackPressedEvent(this)) {
            // lets do the default back action if fragments don't consume it
            super.onBackPressed();
        }
    }
}

For more details and other use-cases visit GitHub page:

https://github.com/skoumalcz/fragment-back

Answer 6

in fragment class put this code for back event:

 rootView.setFocusableInTouchMode(true);
        rootView.requestFocus();
        rootView.setOnKeyListener( new OnKeyListener()
        {
            @Override
            public boolean onKey( View v, int keyCode, KeyEvent event )
            {
                if( keyCode == KeyEvent.KEYCODE_BACK )
                {
                    FragmentManager fragmentManager = getFragmentManager();
                    fragmentManager.beginTransaction()
                            .replace(R.id.frame_container, new Book_service_provider()).commit();

                    return true;
                }
                return false;
            }
        } );