Android Fragments edit

Navigation between fragments using backstack and static fabric pattern

First of all, we need to add our first Fragment at the beginning, we should do it in the onCreate() method of our Activity:

if (null == savedInstanceState) {
    getSupportFragmentManager().beginTransaction()
      .addToBackStack("fragmentA")
      .replace(R.id.container, FragmentA.newInstance(), "fragmentA")
      .commit();
}

Next, we need to manage our backstack. The easiest way is using a function added in our activity that is used for all FragmentTransactions.

public void replaceFragment(Fragment fragment, String tag) {
    //Get current fragment placed in container
    Fragment currentFragment = getSupportFragmentManager().findFragmentById(R.id.container);

    //Prevent adding same fragment on top
    if (currentFragment.getClass() == fragment.getClass()) {
        return;
    }

    //If fragment is already on stack, we can pop back stack to prevent stack infinite growth
    if (getSupportFragmentManager().findFragmentByTag(tag) != null) {
        getSupportFragmentManager().popBackStack(tag, FragmentManager.POP_BACK_STACK_INCLUSIVE);
    }

    //Otherwise, just replace fragment
    getSupportFragmentManager()
            .beginTransaction()
            .addToBackStack(tag)
            .replace(R.id.container, fragment, tag)
            .commit();
}

Finally, we should override onBackPressed() to exit the application when going back from the last Fragment available in the backstack.

@Override
public void onBackPressed() {
    int fragmentsInStack = getSupportFragmentManager().getBackStackEntryCount();
    if (fragmentsInStack > 1) { // If we have more than one fragment, pop back stack
        getSupportFragmentManager().popBackStack();
    } else if (fragmentsInStack == 1) { // Finish activity, if only one fragment left, to prevent leaving empty screen
        finish();
    } else {
        super.onBackPressed();
    }
}

Execution in activity:

replaceFragment(FragmentB.newInstance(), "fragmentB");

Execution outside activity (assuming MainActivity is our activity):

((MainActivity) getActivity()).replaceFragment(FragmentB.newInstance(), "fragmentB");

Table Of Contents
39 ACRA
44 Fragments
64 Menu
112 Loader
119 Xposed
132 Colors
135 Fresco
140 AdMob
147 Button
156 Vk SDK
170 XMPP
176 OpenCV
200 FileIO
203 Moshi
217 Paint
231 AIDL
241 JCodec
243 Okio
255 Looper
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