Android Thread Exception?

Question

i got thread exception in android , what i intend to do is, while clicking a button i started a thread going to dynamically invoke the handler ,handler update the text view with integer value , while reaching integer 10, i going to stop the thread and have to show an alert ,but it will cause an error, what i possibly doing is shown below

public class sample extends Activity implements Runnable{

public Camcorder()
     {
         try{
         counterThread = new Thread(this);
         }catch(Exception ee)
         {

         }
     }

     public void run()
     {
         try{
         while(counterFlag)
         {

             System.out.println("The time starts at : "+counter);

             Thread.sleep(1000); 
             calculate(counter);
             counter++;
         }
         }catch(Exception ee){
             System.out.println("Err in ee : "+ee);
         }
     }
        @Override 
     public void onCreate(Bundle savedInstanceState) { 
          super.onCreate(savedInstanceState); 
          c=this.getApplicationContext();
          requestWindowFeature(Window.FEATURE_NO_TITLE); 
          setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE); 
          setContentView(R.layout.main);
                        authalert3 = new AlertDialog.Builder(this);
              authalert3.setTitle("Save Video");
              authalert3.setMessage("Do you want to save this Video?");
              authalert3.setPositiveButton("Yes", null);
               Button test = (Button) findViewById(R.id.widget33);

          test.setOnClickListener(new View.OnClickListener() {
                 public void onClick(View v) {
                counter = 0;
                 counterFlag = true;
                counterThread.start();

              }


});

public void calculate(int counter2) {
        // TODO Auto-generated method stub

     if(counter2<60){
         if(counter2<10)
         {
             smin="0"+counter2;
         }
         else{
             smin=""+counter2;
         } 
     }
     else{
         hours++;

         counter=0;
         smin="00";
         if(hours<10){
             shours="0"+hours;
         }
         else{
             shours=""+hours;
         }
     }
        handler.sendEmptyMessage(0);

    }


Handler handler = new Handler(){
        public void handleMessage(android.os.Message msg) {
            String tes=shours+":"+smin;




             time.setText(tes);
             test();
        };
    };


public void test(){
 duration=1;
        if(duration==hours){
            counterFlag = false;
            videoPath=camcorderView.stopRecording();
            authalert3.create().show();
            counterThread.stop();

         }


    }

the error is thrown at counterThread.stop();

Anyone suggest me , how to solve this error.

Answer 1

You don't stop threads by calling counterThread.stop. This method is deprecated. In your case, by setting counterFlag = false; your thread should be stopping itself.

You will also be getting an exception if you click twice on your button: you cannot call start on a Thread that has already been started. You must create a new instance of that Thread and start that new instance (stop the old instance before if necessary).

You can see that SO answer for some sample code on how to create/stop threads: Android thread in service issue. I suggest that you also read some tutorial on Java Threads (this is not specific to Android).

---

Additionally I think that you don't need a thread at all, you are doing nothing complicated and thus you could simply use the handler to do all the work:

private static final int MSG_REFRESH_UI = 0;
private static final int MSG_UPDATE_COUNTER = 1;

private int counter = 0;

Handler handler = new Handler(){
    public void handleMessage(android.os.Message msg) {
        if (msg.what==MSG_REFRESH_UI) {
           String tes=shours+":"+smin;
           time.setText(tes);
           test();
        } else if (msg.what==MSG_UPDATE_COUNTER) {
           counter++;
           if (counter<10) {
               calculate(counter);
               handler.sendEmptyMessageDelayed(MSG_UPDATE_COUNTER, 1000);
               handler.sendEmptyMessage(MSG_REFRESH_UI);
           }
        }
    };
};

public void onResume() { 
    handler.sendEmptyMessage(MSG_UPDATE_COUNTER);
}

public void calculate(int counter2) {     
     if (counter2<10) {
         smin = "0"+counter2;
     } else if (counter2<60) { 
         smin = ""+counter2;
     }  else{
         hours++;

         counter=0;
         smin="00";
         if(hours<10){
             shours="0"+hours;
         } else {
             shours=""+hours;
         }
     }
}

Answer 2

This will stop the thread at 10

    while(counterFlag)
         {

             System.out.println("The time starts at : "+counter);

             Thread.sleep(1000); 
             calculate(counter);
             counter++;

             if(counter == 10) counterFlag = false;
         }