Thread Concepts:

Method1:
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.Toast;


public class Method1 extends Activity {


class PrinterTask extends AsyncTask<String, Void, Void> {


protected Void doInBackground(String... x) {
while (true) {
System.out.println(x[0]);
test();


try {
Thread.sleep(1000);
test2();


} catch (InterruptedException ie) {
ie.printStackTrace();
}
}
}
};


@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);


new PrinterTask().execute("---------------------");
//new PrinterTask().execute("foo foo foo");


System.out.println("onCreate() is done.");
}


public void test2() {
// TODO Auto-generated method stub
System.out.println("test2 is done.");
}


public void test() {
// TODO Auto-generated method stub
System.out.println("test is done.");
}
}
Method2:



import android.app.Activity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.KeyEvent;
import android.widget.TextView;


public class Method2 extends Activity implements Runnable {


private String pi_string;
private TextView tv;
private ProgressDialog pd;


@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main2);


tv = (TextView) this.findViewById(R.id.tv);
tv.setText("Press any key to start calculation");
}


public boolean onKeyDown(int keyCode, KeyEvent event) {


pd = ProgressDialog.show(this, "Working..", "Calculating Pi", true,
false);


Thread thread = new Thread(this);

thread.start();



return super.onKeyDown(keyCode, event);
}


public void run() {
pi_string = "gfdsgs";
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
handler.sendEmptyMessage(0);
}


private Handler handler = new Handler() {
public void handleMessage(Message msg) {
pd.dismiss();
tv.setText(pi_string);


}
};


}