How to implement onBackPressed() in Fragments?

Question

Is there a way in which we can implement onBackPressed() in Android Fragment similar to the way in which we implement in Android Activity?

As the Fragment lifecycle do not have onBackPressed(). Is there any other alternative method to over ride onBackPressed() in Android 3.0 fragments?

Answer 1

I solved in this way override onBackPressed in the Activity. All the FragmentTransaction are addToBackStack before commit:

@Override public void onBackPressed() {      int count = getSupportFragmentManager().getBackStackEntryCount();      if (count == 0) {         super.onBackPressed();         //additional code     } else {         getSupportFragmentManager().popBackStack();     }  } 

Answer 2

In my opinion the best solution is:

JAVA SOLUTION

Create simple interface :

public interface IOnBackPressed {     /**      * If you return true the back press will not be taken into account, otherwise the activity will act naturally      * @return true if your processing has priority if not false      */     boolean onBackPressed(); } 

And in your Activity

public class MyActivity extends Activity {     @Override public void onBackPressed() {     Fragment fragment = getSupportFragmentManager().findFragmentById(R.id.main_container);        if (!(fragment instanceof IOnBackPressed) || !((IOnBackPressed) fragment).onBackPressed()) {           super.onBackPressed();        }     } ... } 

Finally in your Fragment:

public class MyFragment extends Fragment implements IOnBackPressed{    @Override    public boolean onBackPressed() {        if (myCondition) {             //action not popBackStack             return true;          } else {             return false;         }     } } 

KOTLIN SOLUTION

1 - Create Interface

interface IOnBackPressed {     fun onBackPressed(): Boolean } 

2 - Prepare your Activity

class MyActivity : AppCompatActivity() {     override fun onBackPressed() {         val fragment =             this.supportFragmentManager.findFragmentById(R.id.main_container)         (fragment as? IOnBackPressed)?.onBackPressed()?.not()?.let {             super.onBackPressed()         }     } } 

3 - Implement in your target Fragment

class MyFragment : Fragment(), IOnBackPressed {     override fun onBackPressed(): Boolean {         return if (myCondition) {             //action not popBackStack             true         } else {             false         }     } }