First one, you need to set the permission in your Manifest.xml
file
<uses-permission android:name="android.permission.SET_WALLPAPER"/>
And you can set the background with this:
Button buttonSetWallpaper = (Button)findViewById(R.id.set);
ImageView imagePreview = (ImageView)findViewById(R.id.preview);
imagePreview.setImageResource(R.drawable.five);
buttonSetWallpaper.setOnClickListener(new Button.OnClickListener(){
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
WallpaperManager myWallpaperManager
= WallpaperManager.getInstance(getApplicationContext());
try {
myWallpaperManager.setResource(R.drawable.five);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}});