想要關掉Toast~請Handler來幫忙Toast.cancel()

Toast.SHORT提示著左邊的ImageButton點選後跳出為期2 秒的Toast
Toast.LONG 提示著右邊的ImageButton點選後跳出為期3.5秒的Toast
按下Cancel Toast Button後可以關閉Toast(必須透過Handler)
但本範例還不夠完善的是, ImageButton交互點選無法立即清掉Thread裡的sleep()...

package com.tsots.CancelToast;

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.Toast;

public class CancelToast extends Activity
{
  Context context = CancelToast.this;
  ProgressDialog myDialog = null;  
  ImageButton ib1;
  ImageButton ib2;
  Button b3;
  String TAG = "CancelToast.this";
  Toast toast_start;
  Thread thread;
  String called_by = null;
  
  volatile boolean terminate = false;
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState)
  {    
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
   
    ib1 = (ImageButton)findViewById(R.id.imagebutton1);
    ib2 = (ImageButton)findViewById(R.id.imagebutton2);
    b3 = (Button)findViewById(R.id.button3);
    
    ib1.setOnClickListener(new ImageButton.OnClickListener()
    {
      public void onClick(View arg0)
      {
        {     
         called_by = "ib1";        
       toast_start = Toast.makeText(context, "Start Short Toast", Toast.LENGTH_SHORT);
            toast_start.show(); 
         ib1.setBackgroundDrawable(getResources().getDrawable(R.drawable.ib_click));
         ib2.setBackgroundDrawable(getResources().getDrawable(R.drawable.ib_unclick));  
            fun_thread();         
        }
      }
 });
    
    ib2.setOnClickListener(new ImageButton.OnClickListener()
    {
      public void onClick(View arg0)
      {
        {    
         called_by = "ib2";         
      toast_start = Toast.makeText(context, "Start Long Toast", Toast.LENGTH_LONG);
            toast_start.show();
         ib1.setBackgroundDrawable(getResources().getDrawable(R.drawable.ib_unclick));
         ib2.setBackgroundDrawable(getResources().getDrawable(R.drawable.ib_click));
            fun_thread();          
        }
      }
 });   
    
    b3.setOnClickListener(new Button.OnClickListener()
   {
    public void onClick(View arg0)
       {
         {         
          called_by = "b3";
             fun_thread();          
         }
       }
   });
  }
  
  public void fun_thread()
  {   
      new Thread()
      { 
        public void run()
        { 
         try
            { 
           if (called_by.equals("ib1"))
           {
           sleep(2000);           
           }
           else if(called_by.equals("ib2"))
           {           
           sleep(3500);
           }     
           else
           {
            Thread.currentThread().interrupt();
            handler.sendEmptyMessage(0);
           }
            }
            catch (Exception e)
            {
              e.printStackTrace();
            }   
            finally
            {
             handler.sendEmptyMessage(0);             
            }
        }         
      }.start(); 
  }

  /*
   * 透過Handler將Toast關閉
   */
  Handler handler = new Handler()
  {
      public void handleMessage(Message msg)
      {       
       toast_start.cancel();
       ib1.setBackgroundDrawable(getResources().getDrawable(R.drawable.ib_unclick));  
       ib2.setBackgroundDrawable(getResources().getDrawable(R.drawable.ib_unclick));  
      }
  };
}