Question

Here is my code

import android.content.Context;
import android.util.AttributeSet;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.widget.Button;

public class MyLongPressCustomButton extends Button{

    private InStock instock;

    public MyLongPressCustomButton(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public MyLongPressCustomButton(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public MyLongPressCustomButton(Context context) {
        super(context);
    }

    public void setSampleLongpress(InStock sl) {
        instock = sl;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        cancelLongpressIfRequired(event);
        return super.onTouchEvent(event);
    }

    @Override
    public boolean onTrackballEvent(MotionEvent event) {
        cancelLongpressIfRequired(event);
        return super.onTrackballEvent(event);
    }

    @Override
    public boolean onKeyUp(int keyCode, KeyEvent event) {
        if ((keyCode == KeyEvent.KEYCODE_DPAD_CENTER)
                || (keyCode == KeyEvent.KEYCODE_ENTER)) {
            cancelLongpress();
        }
        return super.onKeyUp(keyCode, event);
    }

    private void cancelLongpressIfRequired(MotionEvent event) {
        if ((event.getAction() == MotionEvent.ACTION_CANCEL)
                || (event.getAction() == MotionEvent.ACTION_UP)) {
            cancelLongpress();
        }
    }

    private void cancelLongpress() {        
        if (instock != null) {
            instock.cancelLongPress();
        }
    }    
}

I need to use for multi classes, now it only for InStock class, how to change my code for multi classes?
The cancelLongpress() method is undefined when i changed InStock to Activity.

Thanks in advance 🙂

Answer 1

You should use delegate pattern in this case.

  public interface MyDelegate{
      void cancelLongPress();
  }

Then use this delegate for your custom button

 public class MyLongPressCustomButton extends Button{
      MyDelegate delegate;

      public MyLongPressCustomButton (MyDelegate delegate){
          this.delegate = delegate;
      }

      private void cancelLongpress() {        
        if (null  != delegate) {
            delegate.cancelLongPress();
        }
     }              
 }

If you want to use this for many classes, just implement this interface. For example

  public class YourActivity extend Activity implements MyDelegate{
      @override  
      void oncreate(){
           //create new button with a delegate
        MyLongPressCustomButton btn = new  MyLongPressCustomButton(this);
         //do something
      }

      //real work is here
      @override  
      public void cancelLongPress(){

      }
  }