Android - ช่วยแก้โค้ด DragEvent หน่อยค่ะ เราควรเช็คยังไงดีค่ะให้รับแค่ภาพเดียว และรูปอื่นไม่หายไปค่ะ

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/bggame" >

    <ImageButton
        android:id="@+id/btcat"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:layout_marginRight="376dp"
        android:layout_marginTop="35dp"
        android:src="@drawable/btcat" />

    <RelativeLayout
        android:id="@+id/bottomright"
        android:layout_width="150dp"
        android:layout_height="120dp"
        android:layout_alignLeft="@+id/btcat"
        android:layout_alignParentBottom="true"
        android:layout_marginBottom="41dp"
        android:layout_marginLeft="63dp"
        android:background="@drawable/slot" >
    </RelativeLayout>

        <ImageView
            android:id="@+id/ivcat"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/btcat"
            android:layout_marginRight="119dp"
            android:layout_marginTop="26dp"
            android:layout_toLeftOf="@+id/btcat"
            android:src="@drawable/cat" />

        <ImageView
            android:id="@+id/ivbutterfly"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignRight="@+id/btcat"
            android:layout_alignTop="@+id/ivcat"
            android:layout_marginRight="95dp"
            android:src="@drawable/butterfly" />

        <ImageView
            android:id="@+id/ivbuffalo"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignLeft="@+id/bottomright"
            android:layout_alignTop="@+id/ivbutterfly"
            android:layout_marginLeft="65dp"
            android:src="@drawable/buffalo" />

        <ImageView
            android:id="@+id/ivbird"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignTop="@+id/ivbuffalo"
            android:layout_marginLeft="42dp"
            android:layout_toRightOf="@+id/ivbuffalo"
            android:src="@drawable/bird" />
    
</RelativeLayout>

package com.example.test;

import android.app.Activity;
import android.content.ClipData;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.view.DragEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.DragShadowBuilder;
import android.view.View.OnDragListener;
import android.view.View.OnTouchListener;
import android.view.ViewGroup;
import android.widget.RelativeLayout;

public class MainActivity extends Activity {
  
/** Called when the activity is first created. */

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    findViewById(R.id.ivbird).setOnTouchListener(new MyTouchListener());
    findViewById(R.id.ivbuffalo).setOnTouchListener(new MyTouchListener());
    findViewById(R.id.ivbutterfly).setOnTouchListener(new MyTouchListener());
    findViewById(R.id.ivcat).setOnTouchListener(new MyTouchListener());
    //findViewById(R.id.slot).setOnDragListener(new MyDragListener());
    //findViewById(R.id.topright).setOnDragListener(new MyDragListener());
    //findViewById(R.id.bottomleft).setOnDragListener(new MyDragListener());
    findViewById(R.id.bottomright).setOnDragListener(new MyDragListener());

  }

  private final class MyTouchListener implements OnTouchListener {
    public boolean onTouch(View view, MotionEvent motionEvent) {
      if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
        ClipData data = ClipData.newPlainText("", "");
        DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
        view.startDrag(data, shadowBuilder, view, 0);
        view.setVisibility(View.INVISIBLE);
        return true;
      } else {
        return false;
      }
    }
  }

  class MyDragListener implements OnDragListener {
    Drawable enterShape = getResources().getDrawable(R.drawable.black);
    Drawable normalShape = getResources().getDrawable(R.drawable.slot);
    

    @Override
    public boolean onDrag(View v, DragEvent event) {
      int action = event.getAction();
      View dropd = (View) v;
      switch (event.getAction()) {
      case DragEvent.ACTION_DRAG_STARTED:
        // do nothing
        break;
      case DragEvent.ACTION_DRAG_ENTERED:
        v.setBackgroundDrawable(enterShape);
        break;
      case DragEvent.ACTION_DRAG_EXITED:
        v.setBackgroundDrawable(normalShape);
        break;
      case DragEvent.ACTION_DROP:
        // Dropped, reassign View to ViewGroup
        View view = (View) event.getLocalState();
        ViewGroup owner = (ViewGroup) view.getParent();
        owner.removeView(view);
        RelativeLayout container = (RelativeLayout) v;
        container.addView(view);
        view.setVisibility(View.VISIBLE);
        break;
      	case DragEvent.ACTION_DRAG_ENDED:
        v.setBackgroundDrawable(normalShape);
      default:
        break;
      }
      return true;
    }
  }
}