calling Handler from a Thread leads to NullPointerException

Question

I need to call the Handler from a Thread, Here is my Thread:

new Thread(){
    public void run(){
        try{
            Thread.sleep(2000); 
        }
        catch(Exception ex){}

        actHandler.sendEmptyMessage(0);
    }}.start();

I'm calling the Handler like this

actHandler=new Handler(){
    public void handleMessage(android.os.Message msg){

    }
};

Some times its working fine and some times it leads to a NullPointerException at the line actHandler.sendEmptyMessage(0);

Here is all my code:

public class Casinos extends Activity {
    ProgressDialog pd;
    Handler actHandler;

    @Override
    public void onCreate(Bundle bundle){
        super.onCreate(bundle);
        pd=ProgressDialog.show(this,"","Please wait...");
        new Thread(){
            public void run(){
            try{
                Thread.sleep(2000); 
            }
            catch(Exception ex){}

            actHandler.sendEmptyMessage(0);
        }}.start();

        setContentView(R.layout.casinos);

        actHandler = new Handler(){
        public void handleMessage(android.os.Message msg){
            super.handleMessage(msg);
                pd.dismiss();
        }};

    }

}

What to do?

Thanks in advance.

Answer 1

You may have instantiated actHandler after the new Thread() statement.

actHandler = new Handler();

Please show us some more code to verify but this is probably the case.

SOLUTION

You have initialised actHandler after the Thread declaration

public class Casinos extends Activity {
    ProgressDialog pd;
    Handler actHandler;
    @Override
    public void onCreate(Bundle bundle){
        super.onCreate(bundle);
        pd=ProgressDialog.show(this,"","Please wait...");
        //move this HERE!!
        actHandler=new Handler(){
            public void handleMessage(android.os.Message msg)
            {
                super.handleMessage(msg);
                pd.dismiss();
            }
        };

        new Thread(){
            public void run(){
                try{
                    Thread.sleep(2000); 
                }
                catch(Exception ex){}
                actHandler.sendEmptyMessage(0);
            }
        }.start();
        setContentView(R.layout.casinos);
    }
}