Fragment Pressing Back Button

Android Fragment handle back button press

When you are transitioning between Fragments, call addToBackStack() as part of your FragmentTransaction:

FragmentTransaction tx = fragmentManager.beginTransation();
tx.replace( R.id.fragment, new MyFragment() ).addToBackStack( "tag" ).commit();

If you require more detailed control (i.e. when some Fragments are visible, you want to suppress the back key) you can set an OnKeyListener on the parent view of your fragment:

//You need to add the following line for this solution to work; thanks skayred
fragment.getView().setFocusableInTouchMode(true);
fragment.getView().requestFocus();
fragment.getView().setOnKeyListener( new OnKeyListener()
{
    @Override
    public boolean onKey( View v, int keyCode, KeyEvent event )
    {
        if( keyCode == KeyEvent.KEYCODE_BACK )
        {
            return true;
        }
        return false;
    }
} );

How to detect when back button pressed in fragment android?

In your MainActivity

@Override
public void onBackPressed()
{
    FragmentTransaction fragmentTransaction = mFragmentManager.beginTransaction();
    fragmentTransaction.replace(R.id.containerView,new Recommendation()).commit();
}

How to handle Back Button press in android fragments

I think you can do this:

Create a generic Fragment:

public abstract class extends BaseFragment {

    public abstract boolean  onBackPressed();

}

In his Fragments, extends this BaseFragment, example:

public class TopStoriesFragment extends BaseFragment {

    ...

    @Override
    public boolean onBackPressed()
    {
       //if you return false, then it is because you have not consumed 
       //the event, but if it          returns true, which is consumed by this event.
        return false;
    }
}

In his MainActivity activity, you should check in onBackPressed event, if the event was consumed or not, to decide what to do.

It is very important that you save the current tab!

public class MainActivity extends FragmentActivity implements
        ActionBar.TabListener {

       //It is very important that you save the current tab!
       private BaseFragment currentTab;

     // ...  implementation 

public class TabsPagerAdapter extends FragmentPagerAdapter {

    public TabsPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int index) {

         currentTab = null;

        switch (index) {
        case 0:
            // Top Rated fragment activity
            currentTab = new TopStoriesFragment();
       break;
        case 1:
            // Games fragment activity
            return new NationalFragment();
        case 2:
            // Movies fragment activity
            currentTab = new InternationalFragment();
          break;
        case 3:
            // Movies fragment activity
            currentTab = new SportsFragment();
           break;
        case 4:
            // Movies fragment activity
            currentTab = new TechnologyFragment();
        case 5:
            // Movies fragment activity
            currentTab = new BusinessFragment();
         break;
        case 6:
            // Movies fragment activity
            currentTab = new EntertainmentFragment();
        break;
        }

        return currentTab;
    }

    @Override
    public int getCount() {
        // get item count - equal to number of tabs
        return 7;
    }

    public void stop() {
        // get item count - equal to number of tabs
        return;
    }

}

@Override
public void onBackPressed() 
{
  //If the event returned false, then call the super.
  if(currentTab == null || !currentTab.onBackPressed())
  super.onBackPressed();
}

}

Change to your case!

Tap back button twice to terminate application in Fragment

I solved the problem by writing it in override fun onAttach
Please check the code below

    override fun onAttach(context: Context) {
    super.onAttach(context)
    mContext = context as MainActivity

    callback = object : OnBackPressedCallback(true) {
        override fun handleOnBackPressed() {
            if (doubleBackToExitPressedOnce) {
                activity?.finish()
            }
            doubleBackToExitPressedOnce = true
            Handler().postDelayed({ doubleBackToExitPressedOnce = false }, 2000)
            showSnackBar(
                context = mContext,
                layout = binding.layoutMain,
                type = Constants.SnackBarTypes.Warn,
                message = mContext.getString(R.string.tap_twice_to_terminate)
            )
        }
    }
    requireActivity().onBackPressedDispatcher.addCallback(this, callback)
}

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