Using back button to go back to main activity from fragment

Question

Hi I have created fragments in app drawer and now when I am pressing the back button on a fragment, it is closing the application.

There is already one existing onKeyDown in the webView of Main activity.

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (event.getAction() == KeyEvent.ACTION_DOWN) {
        switch (keyCode) {
            case KeyEvent.KEYCODE_BACK:
                if (myWebView.canGoBack()) {
                    myWebView.goBack();
                } else {
                    finish();
                }
                return true;
        }
    }
    return super.onKeyDown(keyCode, event);

For the onBackPressed method

@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }

Fragment Impementation method,

if (fragment != null) {
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.content_main, fragment);
        ft.addToBackStack("close");
        ft.commit();




    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);

Can you tell how exactly you are adding your `fragments` when you click on your drawer item? — himanshu1496, Feb 23 '17 at 13:08
if (fragment != null) { FragmentTransaction ft = getSupportFragmentManager().beginTransaction(); ft.replace(R.id.content_main, fragment); ft.commit(); } DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); drawer.closeDrawer(GravityCompat.START); — Shakti Patra, Feb 23 '17 at 13:28

score 3 · Answer 1 · edited May 23 '17 at 10:31

When you add a fragment to some container or inflate it using xml, it is not added to the backstack and so, when 'onBackPressed' occurs it throws the last activity from the backstack- which is the activity hosting the fragment and thus exiting the application. I think this post: Android: Fragments backStack

can help you, it explains how to add the fragment transaction to the backstack:

FragmentManager fragmentManager = getFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    fragmentTransaction.replace(..............);
    fragmentTransaction.addToBackStack("fragment transaction name, not required");
    fragmentTransaction.commit();

Hi thanks for the solution but this didn't work for me.. I have reposted the question with my fragment implementation... — Shakti Patra, Feb 23 '17 at 13:52

score 1 · Answer 2 · answered Feb 23 '17 at 13:12

You need to do this in following way

@Override
public void onBackPressed() {
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        if (getSupportFragmentManager().getBackStackEntryCount() == 0) {
            //that means your stack is empty and you want to close activity
            finish();
        } else {
            // pop the backstack here
            getSupportFragmentManager().popBackStackImmediate();
        }
    }

}

score 0 · Answer 3 · answered Feb 23 '17 at 13:07

0

I think you dont add the fragments to the backstack.

FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
//your code
fragmentTransaction.addToBackStack("your_tag");

answered Feb 23 '17 at 13:07

Tiko

851
8
15

score 0 · Answer 4 · answered Feb 23 '17 at 13:10

When you evoke a fragment add it to stack like this

fragmentTransaction.addToBackStack("fragment");

and then in onBackPress pop it from stack like this

FragmentManager fm = getActivity()
                .getSupportFragmentManager();
        fm.popBackStack ("fragment", FragmentManager.POP_BACK_STACK_INCLUSIVE);

Using back button to go back to main activity from fragment

4 Answers4