How to handle OnBack Click in Android Snippet

Question

I have 3 fragments in my application, for example HomePage , Frag1 ,Frag2,Frag3,Frag4.

So what happens, I used the navigation box in my application. On the home page, I have a grid that has a link to all four fragments. If the user goes fromHomepage -> Frag1 -> Frag1.2 ->Frag1.3 ->HomePage.

So, onBack click to show the previous fragments, but as soon as the user is on the main page, and if he clicks on the back, I want to close my application. I don’t understand how we can do this.

This is how I call fragments from the Navigation Box :

protected void getUrl(int position) {
        FragmentTransaction fragTran = getSupportFragmentManager()
                .beginTransaction();
        switch (position) {
        case 0:
            fragTran.replace(R.id.content_frame, dashboardFragment);
            fragTran.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
            // fragTran.addToBackStack(null);
            fragTran.commit();
            break;
        case 1:

            if (CommonUtils.isNetworkConnected(getApplicationContext())) {
                fragTran.replace(R.id.content_frame, frag1);
                fragTran.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
                fragTran.addToBackStack(null);
                fragTran.commit();

            } else {
                Toast.makeText(getApplicationContext(),
                        "No Network Connection", Toast.LENGTH_LONG).show();
            }
            break;
        case 2:

            if (CommonUtils.isNetworkConnected(getApplicationContext())) {
                fragTran.replace(R.id.content_frame, frag2);
                fragTran.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
                fragTran.addToBackStack(null);
                fragTran.commit();

            } else {
                Toast.makeText(getApplicationContext(),
                        "No Network Connection", Toast.LENGTH_LONG).show();
            }
            break;
        case 3:
            if (CommonUtils.isNetworkConnected(getApplicationContext())) {
                fragTran.replace(R.id.content_frame, frag3);
                fragTran.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
                fragTran.addToBackStack(null);
                fragTran.commit();

            } else {
                Toast.makeText(getApplicationContext(),
                        "No Network Connection", Toast.LENGTH_LONG).show();
            }

            break;



        default:
            // return "";
        }
    }

This is how I call from GridView onClick:

final FragmentTransaction fragTran = getFragmentManager()
                .beginTransaction();

        gridView.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> arg0, View v, int arg2,
                    long arg3) {
                if (DASHBOARD_LINKS[arg2].equals("frag1")) {
                    if (CommonUtils.isNetworkConnected(getActivity())) {
                        fragTran.replace(R.id.content_frame,
                                frag1);
                        fragTran.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
                        fragTran.addToBackStack(null);
                        fragTran.commit();
                    } else {
                        Toast.makeText(getActivity(), "No Network Connection",
                                Toast.LENGTH_LONG).show();
                    }
                }
                if (DASHBOARD_LINKS[arg2].equals("frag2")) {
                    fragTran.replace(R.id.content_frame, frag2);
                    fragTran.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
                    fragTran.addToBackStack(null);
                    fragTran.commit();
                }
                if (DASHBOARD_LINKS[arg2].equals("frag3")) {
                    fragTran.replace(R.id.content_frame, frag3);
                    fragTran.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
                    fragTran.addToBackStack(null);
                    fragTran.commit();
                }
            }
        });

Answer 1

:

int count = fragmentManager.getBackStackEntryCount();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.content_frame, dashboardFragment)
        .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
        .addToBackStack(String.valueOf(count))
        .commit();

, , , . , :

fragmentManager.popBackStackImmediate("0", 0); // "0" here is a tag of transaction you added before. "0" is for first added fragment (your home fragment, I assume). You can pop back stack to second with "1", if you like

, "".

, , :

@Override
public void onBackPressed() {
    if (fragmentManager.getBackStackEntryCount() <= 1) {
        finish();      
        return;
    }
    super.onBackPressed();
}

, .

Answer 2

addToBackStack (null);

 fragTran.replace(R.id.content_frame, dashboardFragment);
        fragTran.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
         fragTran.addToBackStack(null);
        fragTran.commit();

, addToBackStack (null), , .

Answer 3

. & .