Develop Reference

Using BackButton in Fragments Android

I'd like to use the BackButton in Fragments. I'm using this code to handle backbutton:
#Override
public void onResume() {
super.onResume();
getView().setFocusableInTouchMode(true);
getView().requestFocus();
getView().setOnKeyListener(new View.OnKeyListener() {
#Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK){
if (idozit.num > 0) {
if (!pmenu.pauseopen) {
pmenu.BeingPaused(idozit.idozitomegy,nextlevel,0);
} else {
pmenu.continuegame();
}
}
if (idozit.num == 0) {
idozit.numnull(db);
}
//Toast.makeText(getActivity(), "hello1", Toast.LENGTH_SHORT).show();
return true;
}
return false;
}
});
}
When I click on BackButton this code works fine BUT if click on the BackButton again the app calls the onBackPressed method from MainActivity. I don't know why but if I'm using only a Toast or Log.d something like that in the onKey method then I'm able to click it again.
I'd like to say that pmenu is a simple class which is only stops music,make things gone etc. It's seems like somehow I always stuck in that class .
Have you any idea what am I doing wrong?

A cleaner solution is to make an Interface implemented by every fragment with a method called onBackPressed() like this:
public interface FragmentInterface {
void onBackPressed();
}
Then, you override the onBackPressed in yout activity calling your current fragment's onBackPressed (I'm assuming that you have a method to get your currentFragment)
#Override
public void onBackPressed(){
FragmentInterface currentfragment = getCurrentFragment();
currentfragment.onBackPressed();
}
Of course, in your fragment, implemented method should look like this:
#Override
public void onBackPressed() {
if (idozit.num > 0) {
if (!pmenu.pauseopen) {
pmenu.BeingPaused(idozit.idozitomegy,nextlevel,0);
} else {
pmenu.continuegame();
}
}
if (idozit.num == 0) {
idozit.numnull(db);
}
//Toast.makeText(getActivity(), "hello1", Toast.LENGTH_SHORT).show();
}

Replace false in last line with true and there's no need for return true before the last one

Android: Detect back button release

I am able to detect when the back button is pressed by using:
#Override
public void onBackPressed() {
//Do my thing
}
But now I want to detect when the back button is released. How can I do that? I'm unable to find any method like onBackReleased() which I can override to do my thing.

There is no method that specifically detects the back button release, but you could use the onKeyDown() and onKeyUp() methods. Check to make sure the key is the back button, and do your stuff in the method. Here is something you could do:
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
// do your stuff for when the back button is initially pressed
return true;
} else {
return false;
}
}
#Override
public boolean onKeyUp(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
// do your stuff for when the back button is released
return true;
} else {
return false;
}
}
If you wanted to override the default back press, you could just use the onBackPressed() method, like so:
#Override
public void onBackPressed() {
// Prevents the user from clicking the back button and returning to the parent activity
}
These methods can be implemented directly in your class. Hope it helps!

How to disable back button pressed for webview in android?

How to disable back button pressed for webview in android ?
#Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
if (wv1 != null && (keyCode == KeyEvent.KEYCODE_BACK)
&& wv1.canGoBack() )
{
wv1.goBack();
}
return true;
}

If you want to disable back button action when the WebView Visible and enable back button action if the WebView in not Visible try the below code in your Activity
#Override
public void onBackPressed() {
if(webview.getVisibility()==View.VISIBLE){
// dont pass back button action
if(webview.canGoBack()){
webview.goBack();
}
return;
}else{
// pass back button action
super.onBackPressed();
}
}

Simply override the onBackPressed() method.
#Override
public void onBackPressed() { }

Please try this
#Override
public void onBackPressed() {
if(webview.canGoBack()){
webview.goBack();
}
else{
super.onBackPressed();
}
}

There are many ways to make it,
Solution 1, overriding dispatchKeyEvent()
dispatchKeyEvent()(API Level 1, Android 1.0)
Refer to my answer use dispatchKeyEvent to disable back button
#Override
public boolean dispatchKeyEvent(KeyEvent event) {
// TODO Auto-generated method stub
if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
return true;
}
return super.dispatchKeyEvent(event);
}
Solution 2, overriding onBackPressed()
onBackPressed() (API Level 5, Android 2.0)
Refer to Use onBackPressed() to disable back button
#Override
public void onBackPressed() {
}
Solution 3, overriding onKeyDown()
onKeyDown() (API Level 1, Android 1.0)
Refer to Use onKeyDown() to disable back button
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
//preventing default implementation previous to android.os.Build.VERSION_CODES.ECLAIR
return true;
}
return super.onKeyDown(keyCode, event);
}

You have add below code in Activity for disable activity back pressed
#Override
public void onBackPressed() {
}

Add this below code in java file :
WebView mwebView;
Button backButton1;
backButton1 = findViewById(R.id.backButton1);
mwebView = findViewById(R.id.mwebView);
backButton1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
mWebView.destroy();
}
});

Disable Back Button press from fragment

My application has an activity with so many fragments. I want to disable the back button press in some fragment. I tried with the below code. But it doesn't work.
In the main activity:
#Override
public void onBackPressed() {
super.onBackPressed();
OrderFragment.onBackPress();
}
In the fragment,
public static void onBackPressed()
{
Log.d(TAG,"It listen");
}
I have the log message but, how can I disable the back button from my fragment.

You should keep a reference to the fragment you want to disable/handle back press event on your main activity:
class MainActivity{
OrderFragment mOrderFragment;
#Override
public void onBackPressed() {
if(mOrderFragment.isVisible())
mOrderFragment.onBackPressed();
else
super.onBackPressed();
}
}
In OrderFragment:
public void onBackPressed() {
//handle back press event
}

In your oncreateView() method you need to write this code and in KEYCODE_BACk return should true then it will stop the back button option for particular fragment
View v = inflater.inflate(R.layout.xyz, container, false);
//Back pressed Logic for fragment
v.setFocusableInTouchMode(true);
v.requestFocus();
v.setOnKeyListener(new View.OnKeyListener() {
#Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_DOWN) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
return true;
}
}
return false;
}
});

getView().setFocusableInTouchMode(true);
getView().requestFocus();
getView().setOnKeyListener(new View.OnKeyListener() {
#Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if( keyCode == KeyEvent.KEYCODE_BACK ) {
// leave this blank in order to disable the back press
return true;
} else {
return false;
}
}
});

I think you have to Override onResume method in fragments which you need to disable the back press.Tryout the following code.
#Override
public void onResume() {
super.onResume();
this.getView().setFocusableInTouchMode(true);
this.getView().requestFocus();
this.getView().setOnKeyListener(new View.OnKeyListener() {
#Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
return true;
}
return false;
}
});
}

Have you tried like this, Actually it works for me before.
you can set listener for Back key. if you add it, i guess it works.
youfragment.getView().setOnKeyListener( new OnKeyListener()
{
#Override
public boolean onKey( View v, int keyCode, KeyEvent event )
{
if( keyCode == KeyEvent.KEYCODE_BACK )
{
return true;
}
return false;
}
}
);

super.onBackPressed in the activity is the default implementation. Remove this if you don't want it.

I know this is an old question and because of navigation components and new ways this situation rarely occurs, still, maybe my answer helps someone.
I came across a similar situation where I needed the back button to be disabled and I couldn't change the activity as well. So in a fragment, I added this code block.
Language: Kotlin
override fun onResume() {
super.onResume()
this.requireView().isFocusableInTouchMode = true
this.requireView().requestFocus()
this.requireView().setOnKeyListener { _, keyCode, _ ->
keyCode == KeyEvent.KEYCODE_BACK
}
}
This will disable your back press on that specific fragment

#Override
public void onBackPressed() {
Fragment currentFragment = getSupportFragmentManager().findFragmentById(R.id.fragment_container);
if (currentFragment instanceof YourFragment) {
currentFragment.onBackPressed();
} else
super.onBackPressed();
}

override fun onBackPressed() {
val currentFragment = findNavController(R.id.nav_host_fragment).currentDestination?.id
if (currentFragment == R.id.YourFragment) {
return
}
super.onBackPressed()

If you don't want your fragment to be in the backstack you can do so, by not adding it to the backstack in the transaction. So do NOT call FragmentTransaction.addToBackStack(); on the fragments you do not want in your backstack.

onBackPressed works like this:
public void More onBackPressed() {
if (!mFragments.popBackStackImmediate()) {
finish();
}
}
Thus when you call super.onBackPressed() you pop the BackStack before finishing the activity. The best way to sort this out is to make sure you do not add the fragments to the BackStack. It is normally done like this:
fragmentTransaction.addToBackStack(TAG);
An alternative solution, but uglier since you have still useless code left, would be making onBackPressed() directly call finish() to end the activity.
I would strongly advise you not use getView().setOnKeyListener(...) since it is code smell.

Try this
public void onBackPressed() {
if (!mFragments.popBackStackImmediate()) {
finish();
}else{
super.onBackPressed();}
}

How can I close my application on back pressed

I want to close application when I press device's back button.I am using this code..
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
// do something on back.
this.finish();
return true;
}
return super.onKeyDown(keyCode, event);
}

Override the onBackPressed() in your Activity where you want application to Quit when the device back button clicked
#Override
public void onBackPressed() {
android.os.Process.killProcess(android.os.Process.myPid());
}

This code does it :
public void onPause() {
super.onPause();
finish();
}
Don't forget to mark it as answer if it helped ;)

The answer that you marked as correct will stop the app every onPause of this activity, which is not an event of the back button cick, the right answer is :
#Override
public void onBackPressed() {
finish();
}