Drag And Drop to copy items between ListView

Last exercise demonstrate how to "Passing object in Drap And Drop using myLocalState". In this exercise, demonstrate how to copy items between ListView by Drag And Drop.

User can drap a item from listSource, the long clicked item is copy to item in dragData, then drop on listTarget to add it.



Modify main.xml to have two ListView.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical" >

  <TextView
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:text="@string/hello" />

  <LinearLayout
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      android:orientation="horizontal" >
      <LinearLayout
       android:layout_width="0dp"
       android:layout_height="fill_parent"
       android:layout_weight="1"
       android:orientation="vertical" >
   <ScrollView
       android:layout_width="fill_parent"
        android:layout_height="fill_parent">
        <TextView
            android:id="@+id/comments"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content" />
    </ScrollView>
   </LinearLayout>
   <LinearLayout
       android:layout_width="0dp"
       android:layout_height="fill_parent"
       android:layout_weight="1"
       android:orientation="vertical" >
       <TextView
           android:layout_width="fill_parent"
           android:layout_height="wrap_content"
           android:text="Drag Source" />
       <ListView
           android:id="@+id/sourcelist"
           android:layout_width="fill_parent"
           android:layout_height="wrap_content"/>

   </LinearLayout>
   <LinearLayout
       android:id="@+id/targetlayout"
       android:layout_width="0dp"
       android:layout_height="fill_parent"
       android:layout_weight="1"
       android:orientation="vertical" >
       <TextView
           android:layout_width="fill_parent"
           android:layout_height="wrap_content"
           android:text="Drop Target" />
       <ListView
           android:id="@+id/targetlist"
           android:layout_width="fill_parent"
           android:layout_height="wrap_content"/>
   </LinearLayout>
  </LinearLayout>

</LinearLayout>

Java Code:

package com.exercise.com;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.content.ClipData;
import android.content.ClipDescription;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Point;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.view.DragEvent;
import android.view.View;
import android.view.View.DragShadowBuilder;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.TextView;

public class AndroidDragAndDropActivity extends Activity {
 
 LinearLayout targetLayout;
 ListView listSource, listTarget;
 TextView comments;
 
 String commentMsg;
 
 MyDragEventListener myDragEventListener = new MyDragEventListener();
 
 String[] month ={
   "January",
   "February",
   "March",
   "April",
   "May",
   "June",
   "July",
   "August",
   "September",
   "October",
   "November",
   "December"};
 
 List<String> droppedList;
 ArrayAdapter<String> droppedAdapter;
 
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      targetLayout = (LinearLayout)findViewById(R.id.targetlayout);
      listSource = (ListView)findViewById(R.id.sourcelist);
      listTarget = (ListView)findViewById(R.id.targetlist);
      comments = (TextView)findViewById(R.id.comments);
    
      // Create and set the tags for the Buttons
      final String SOURCELIST_TAG = "listSource";
      final String TARGETLIST_TAG = "listTarget";
      final String TARGETLAYOUT_TAG = "targetLayout";

      listSource.setTag(SOURCELIST_TAG);
      listTarget.setTag(TARGETLIST_TAG);
      targetLayout.setTag(TARGETLAYOUT_TAG);

      listSource.setAdapter(new ArrayAdapter<String>(this,
              android.R.layout.simple_list_item_1, month));
      listSource.setOnItemLongClickListener(listSourceItemLongClickListener);
    
    
      droppedList = new ArrayList<String>();
      droppedAdapter = new ArrayAdapter<String>(this,
              android.R.layout.simple_list_item_1, droppedList);
      listTarget.setAdapter(droppedAdapter);
    
      listSource.setOnDragListener(myDragEventListener);
      targetLayout.setOnDragListener(myDragEventListener);

  }

  OnItemLongClickListener listSourceItemLongClickListener
  = new OnItemLongClickListener(){

  @Override
  public boolean onItemLongClick(AdapterView<?> l, View v,
    int position, long id) {
   
   //Selected item is passed as item in dragData
   ClipData.Item item = new ClipData.Item(month[position]);
   
   String[] clipDescription = {ClipDescription.MIMETYPE_TEXT_PLAIN};
   ClipData dragData = new ClipData((CharSequence)v.getTag(),
     clipDescription,
     item);
   DragShadowBuilder myShadow = new MyDragShadowBuilder(v);

   v.startDrag(dragData, //ClipData
                  myShadow,  //View.DragShadowBuilder
                  month[position],  //Object myLocalState
                  0);    //flags
   
   commentMsg = v.getTag() + " : onLongClick.\n";
   comments.setText(commentMsg);
   
   return true;
  }};
  
 private static class MyDragShadowBuilder extends View.DragShadowBuilder {
  private static Drawable shadow;
  
  public MyDragShadowBuilder(View v) {
   super(v);
   shadow = new ColorDrawable(Color.LTGRAY);
      }
  
  @Override
      public void onProvideShadowMetrics (Point size, Point touch){
          int width = getView().getWidth();
          int height = getView().getHeight();

          shadow.setBounds(0, 0, width, height);
          size.set(width, height);
          touch.set(width / 2, height / 2);
      }

      @Override
      public void onDrawShadow(Canvas canvas) {
          shadow.draw(canvas);
      }
  
 }
 
 protected class MyDragEventListener implements View.OnDragListener {

  @Override
  public boolean onDrag(View v, DragEvent event) {
   final int action = event.getAction();
   
   switch(action) {
   case DragEvent.ACTION_DRAG_STARTED:
    //All involved view accept ACTION_DRAG_STARTED for MIMETYPE_TEXT_PLAIN
              if (event.getClipDescription()
                .hasMimeType(ClipDescription.MIMETYPE_TEXT_PLAIN))
              {
               commentMsg += v.getTag()
                 + " : ACTION_DRAG_STARTED accepted.\n";
               comments.setText(commentMsg);
               return true; //Accept
              }else{
               commentMsg += v.getTag()
                 + " : ACTION_DRAG_STARTED rejected.\n";
               comments.setText(commentMsg);
               return false; //reject
              }
   case DragEvent.ACTION_DRAG_ENTERED:
    commentMsg += v.getTag() + " : ACTION_DRAG_ENTERED.\n";
    comments.setText(commentMsg);
    return true;
   case DragEvent.ACTION_DRAG_LOCATION:
    commentMsg += v.getTag() + " : ACTION_DRAG_LOCATION - "
     + event.getX() + " : " + event.getY() + "\n";
    comments.setText(commentMsg);
    return true;
   case DragEvent.ACTION_DRAG_EXITED:
    commentMsg += v.getTag() + " : ACTION_DRAG_EXITED.\n";
    comments.setText(commentMsg);
    return true;
   case DragEvent.ACTION_DROP:
    // Gets the item containing the dragged data
              ClipData.Item item = event.getClipData().getItemAt(0);

              commentMsg += v.getTag() + " : ACTION_DROP" + "\n";
    comments.setText(commentMsg);
    
    //If apply only if drop on buttonTarget
    if(v == targetLayout){
     String droppedItem = item.getText().toString();
     
     commentMsg += "Dropped item - "
                   + droppedItem + "\n";
     comments.setText(commentMsg);
     
     droppedList.add(droppedItem);
     droppedAdapter.notifyDataSetChanged();
     
     return true;
    }else{
     return false;
    }
            
            
   case DragEvent.ACTION_DRAG_ENDED:
    if (event.getResult()){
     commentMsg += v.getTag() + " : ACTION_DRAG_ENDED - success.\n";
     comments.setText(commentMsg);
    } else {
     commentMsg += v.getTag() + " : ACTION_DRAG_ENDED - fail.\n";
     comments.setText(commentMsg);
    };
              return true;
   default: //unknown case
    commentMsg += v.getTag() + " : UNKNOWN !!!\n";
    comments.setText(commentMsg);
    return false;

   }
  } 
 }
}

Download the files.