Fragments anyone ?

What is a Fragment?
Design
Backward compatibility
Lifecycle
Managing
Transaction
Best practices
DialogFragment

Transcript

1. Fragments anyone? Leonid Olevsky, Yossi Elkrief http://developer.android.com/guide/components/fragments.html
2. Content • What is a Fragment? • Design • Backward compatibility • Lifecycle • Managing • Transaction • Best practices • DialogFragment
3. Fragment ? Fragment = partial behavior of user interface • Modular design to different screen orientations and multiple screen sizes • Multiple fragments can reside in a single activity • Reuse a fragment in multiple activities • Has its own lifecycle
4. Design • Fragments were introduced in Android 3.0 • Support more dynamic and flexible UI designs on large screens • Allow designs without the need to manage complex changes to the view hierarchy • What about previous versions of Android?
5. Backward compatibility • Compatibility Package • Targeting 1.6 (API 4) or later • APIs work almost exactly the same as their counterparts in the latest Android platform ◦ android.support.v4.app.FragmentActivity ◦ android.support.v4.app.Fragment ◦ android.support.v4.app.FragmentManager ◦ android.support.v4.app.FragmentTransaction
6. Lifecycle
7. Adding Fragments Via layout <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android. com/apk/res/android" android:orientation="horizontal" android:layout_width="match_parent" android:layout_height="match_parent"> <fragment android:name="com.gdg.FirstFragment" android:id="@+id/list" android:layout_weight="1" android:layout_width="0dp" android:layout_height="match_parent" /> <fragment android:name="com.gdg.SecondFragment" android:id="@+id/viewer" android:layout_weight="2" android:layout_width="0dp" android:layout_height="match_parent" /> </LinearLayout> Identifiers : id, tag, id of fragment container.
8. Adding Fragments Via Code • specify a ViewGroup in which to place the fragment • using the add() method, specifying the fragment to add and the view in which to insert FragmentManager fragmentManager = getFragmentManager() FragmentTransaction fragmentTransaction = fragmentManager. beginTransaction(); ExampleFragment fragment = new ExampleFragment(); fragmentTransaction.add(R.id.fragment_container, fragment); fragmentTransaction.commit();
9. Adding Fragments without a UI • provide a background behavior for the activity without presenting additional UI • it does not receive a call to onCreateView() ExampleFragment fragment = new ExampleFragment(); fragmentTransaction.add(fragment, "FragmentTag"); fragmentTransaction.commit(); • get the fragment from the activity later, you need to use findFragmentByTag()
10. Managing • FragmentManager ◦ getFragmentManager() ▪ findFragmentById() ▪ findFragmentByTag() ▪ popBackStack() ▪ addOnBackStackChangedListener()
11. Handling fragments example • FragmentManager + FragmentTransaction • Usage: // Create new fragment and transaction Fragment newFragment = new ExampleFragment (); FragmentTransaction transaction = getFragmentManager().beginTransaction (); // Replace whatever is in the fragment_container view with this fragment, // and add the transaction to the back stack transaction.replace(R.id.fragment_container , newFragment); transaction.addToBackStack (null); // Commit the transaction transaction.commit();
12. Fragments Special care • run-time configuration change can cause the activity automatically re-instantiate existing fragments. // Tell the framework to try to keep this fragment around // during a configuration change. setRetainInstance(true); • Check your Bundle. public void onCreate(Bundle savedInstanceState) { if (savedInstanceState == null){ Do Create the Fragment }else{ Activity was recreated } }
13. Best Practices • Fragment Interfaces Invoke Activity ◦ Use event callbacks. • Activity as commutator
14. DialogFragment • showDialog / dismissDialog - deprecated • floating on top of its activity's window • v4 support library (for backward compatibility on pre-Honeycomb devices)
15. DialogFragment - class import android.support.v4.app.DialogFragment; // ... public class EditNameDialog extends DialogFragment { private EditText mEditText; public EditNameDialog() { // Empty constructor required for DialogFragment } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fragment_edit_name, container); mEditText = (EditText) view.findViewById(R.id.txt_your_name); getDialog().setTitle("Hello"); return view; } }
16. DialogFragment - with interface @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fragment_edit_name, container); mEditText = (EditText) view.findViewById(R.id.txt_your_name); getDialog().setTitle("Hello"); // Show soft keyboard automatically mEditText.requestFocus(); getDialog().getWindow().setSoftInputMode(LayoutParams.SOFT_INPUT_STATE_VISIBLE); mEditText.setOnEditorActionListener(this); // when we press done return view; } @Override public boolean onEditorAction(TextView v, int actionId, KeyEvent event) { if (EditorInfo.IME_ACTION_DONE == actionId) { // Return input text to activity EditNameDialogListener activity = (EditNameDialogListener) getActivity(); activity.onFinishEditDialog(mEditText.getText().toString()); this.dismiss(); return true; } return false; }
17. DialogFragment - Showing import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentManager; // ... public class FragmentDialogDemo extends FragmentActivity implements EditNameDialogListener { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); showEditDialog(); } private void showEditDialog() { FragmentManager fm = getSupportFragmentManager(); EditNameDialog editNameDialog = new EditNameDialog(); editNameDialog.show(fm, "fragment_edit_name"); } @Override public void onFinishEditDialog(String inputText) { Toast.makeText(this, "Hi, " + inputText, Toast.LENGTH_SHORT).show(); } }
18. Sample Fragments application https://github.com/MaTriXy/FragmentsGDG
19. Questions? http://developer.android.com/guide/components/fragments.html