Using ViewFlipper in Android App

Suppose you want to display a news bar in your activity. this news bar displays a single news item at a time then flips and shows next item and so on, then your choice would be Android's ViewFlipper.

ViewFlipper inherits from frame layout, so it displays a single view at a time.
consider this layout:

1. <?xml version="1.0" encoding="utf-8"?>
2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
3.    android:orientation="vertical"
4.    android:layout_width="fill_parent"
5.    android:layout_height="fill_parent"
6.    >
7. <TextView
8.    android:layout_width="fill_parent"
9.    android:layout_height="wrap_content"
10.    android:text="@string/hello"/>
12.     <Button
13.    android:layout_width="wrap_content"
14.    android:layout_height="wrap_content"
15.    android:text="Flip"
16.    android:id="@+id/btn"
17.    android:onClick="ClickHandler"/>
18.     <ViewFlipper
19.    android:layout_width="fill_parent"
20.    android:layout_height="fill_parent"
21.    android:id="@+id/flip">
22.     <TextView
23.    android:layout_width="fill_parent"
24.    android:layout_height="wrap_content"
25.    android:text="Item1"/>
26.     <TextView
27.    android:layout_width="fill_parent"
28.    android:layout_height="wrap_content"
29.    android:text="Item2"/>
31.     <TextView
32.    android:layout_width="fill_parent"
33.    android:layout_height="wrap_content"
34.    android:text="Item3"/>
35.     </ViewFlipper>
36. </LinearLayout>

Just a ViewFlipper container that contains three text views

Now we want to flip the views when the button is clicked.

1. public void onCreate(Bundle savedInstanceState) {
2.     super.onCreate(savedInstanceState);
3.     setContentView(R.layout.main);
4.     btn=(Button)findViewById(R.id.btn);
5.     flip=(ViewFlipper)findViewById(R.id.flip);
6. }
8. public void ClickHandler(View v)
9. {
10.     flip.showNext();
11. }

If we want to flip in reverese direction we could use flip.showPrevious() instead. If you want to flip to a specific view do the following: flip.setDisplayedChild(indexOfView) replace indexOfView with the integer representing the index of the view you want to switch to.

We can add animations to the child views when they appear or disappear:

1. public void onCreate(Bundle savedInstanceState) {
2.     super.onCreate(savedInstanceState);
3.     setContentView(R.layout.main);
5.     btn=(Button)findViewById(R.id.btn);
7.     flip=(ViewFlipper)findViewById(R.id.flip);
8.     //when a view is displayed
9.     flip.setInAnimation(this,android.R.anim.fade_in);
10.     //when a view disappears
11.     flip.setOutAnimation(this, android.R.anim.fade_out);
12. }

We can also set the ViewFlipper to flip views automatically when the button is clicked:

1. public void ClickHandler(View v)
2. {
3.     //specify flipping interval
4.     flip.setFlipInterval(1000);
5.     flip.startFlipping();
6. }

We can stop the flipping by calling flip.stopFlipping(); method or we can set the flipper to flip autommatically when the activity starts by changing our code.

1. public void onCreate(Bundle savedInstanceState) {
2.     super.onCreate(savedInstanceState);
3.     setContentView(R.layout.main);
5.     btn=(Button)findViewById(R.id.btn);
6.     flip=(ViewFlipper)findViewById(R.id.flip);
7.     flip.setInAnimation(this,android.R.anim.fade_in);
8.     flip.setOutAnimation(this, android.R.anim.fade_out);
9.     flip.setFlipInterval(1000);
10.     flip.setAutoStart(true);    
11. }

More about this control you can read by this url: http://developer.android.com/reference/android/widget/ViewFlipper.html