Fragments

A Fragment:
- Is a modular and reusable piece of UI
- Has its own lifecycle
- Is always hosted by an Activity
- Can be added, removed, replaced at runtime

Creating fragments

Create a container in Activity's layout file to host the fragment.

<FrameLayout
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

Use FragmentManager to add, replace, or remove fragments from the activity.

// Get Fragment Manager
FragmentManager fragmentManager = getSupportFragmentManager();

// Begin Fragment Transaction
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

// Perform Fragment Transaction
if (flag) {
    fragmentTransaction.add(R.id.container, fragment);
} else {
    fragmentTransaction.replace(R.id.container, fragment);
}

// Add the Fragment Transaction to the back stack
fragmentTransaction.addToBackStack(null);

// Commit the Fragment Transaction
fragmentTransaction.commit();

Data passing b/w Activity and Fragment

MainActivity.java

FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

FirstFragment fragment1 = new FirstFragment();

Bundle args = new Bundle();
args.putString("number", "10");
fragment1.setArguments(args);

fragmentTransaction.add(R.id.container1, fragment1);
fragmentTransaction.commit();

FirstFragment.java

onCreateView() {
    String str = "";
    if (getArguments() != null) {
        str = getArguments().getString("number");
    }
}

Last modified: 05 February 2026