CODEWITHSUNDEEP
javaandroideclipse
blended
blended

Reputation: 183

Image Button cannot be cast to widget Button

I tried the following from similar stack overflow Clean ,Build Project Restart Eclipse

I also tried update everything : from SDK and Eclipse plugin Restart emulator etc

Log Cat output: 

09-26 22:11:49.182: E/AndroidRuntime(1393): FATAL EXCEPTION: main
09-26 22:11:49.182: E/AndroidRuntime(1393): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ass2/com.example.ass2.MP3Player}: java.lang.ClassCastException: android.widget.ImageButton cannot be cast to android.widget.Button
09-26 22:11:49.182: E/AndroidRuntime(1393):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at android.os.Looper.loop(Looper.java:137)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at android.app.ActivityThread.main(ActivityThread.java:5041)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at java.lang.reflect.Method.invokeNative(Native Method)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at java.lang.reflect.Method.invoke(Method.java:511)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at dalvik.system.NativeStart.main(Native Method)
09-26 22:11:49.182: E/AndroidRuntime(1393): Caused by: java.lang.ClassCastException: android.widget.ImageButton cannot be cast to android.widget.Button
09-26 22:11:49.182: E/AndroidRuntime(1393):     at com.example.ass2.MP3Player.onCreate(MP3Player.java:30)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at android.app.Activity.performCreate(Activity.java:5104)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
09-26 22:11:49.182: E/AndroidRuntime(1393):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
09-26 22:11:49.182: E/AndroidRuntime(1393):     ... 11 more

Code 

public class MP3Player extends Activity{

    Button prev , play , stop , next , choosefiles;
    ArrayAdapter<Song> adaptor;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      this.setContentView(R.layout.mp3player);


    //Bitmap         mDummyAlbumArt = BitmapFactory.decodeResource(getResources(), R.drawable.dummy_album_art);


     prev =(Button)findViewById(R.id.prev);
     play =(Button)findViewById(R.id.play);
     stop =(Button)findViewById(R.id.stop);
     next =(Button)findViewById(R.id.next);
     prev.setOnClickListener(new OnPress());
     play.setOnClickListener(new OnPress());
     stop.setOnClickListener(new OnPress());
     next.setOnClickListener(new OnPress());

    List<Song> playlist = new ArrayList<Song>();

    System.out.println("Before adapter on creat");

    Song test= new Song("sakis","rouvas","name","path");
    playlist.add(test);

    ListView list = (ListView) findViewById(R.id.listview);
    adaptor = new ArrayAdapter<Song>(this,
            R.layout.list_row, playlist);
    list.setAdapter(adaptor);
    registerForContextMenu(list);

    System.out.println("after adapter on craet");
}     `

Upvotes: 2

Views: 6405

Answers (1)

Christopher Gertz
Christopher Gertz

Reputation: 2026

ImageButton is not a child of Button, no matter what the name suggests. See http://developer.android.com/reference/android/widget/ImageButton.html It extends ImageView, not Button. One of the lines

 prev =(Button)findViewById(R.id.prev);
 play =(Button)findViewById(R.id.play);
 stop =(Button)findViewById(R.id.stop);
 next =(Button)findViewById(R.id.next);

causes this error because the view is an ImageButton, not a Button. In fact, since you only assign OnClickListeners to the views, casting them seems not necessary. "View" will do. This, of course, depends on the rest of your code but in general you should not cast to child views if you don't use the child methods. Especially for switching between Buttons and ImageButtons this can be a pain.

Upvotes: 6

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