MyActivity.java

package com.example.myproject;

import java.util.Date;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;

public class MyActivity extends Activity
{
  private final String[] LETTERS = {"A", "n", "d", "r", "o", "i", "d"};
  private final String HELLO_COMMA_STR = "Hello, ";
  private final Handler uiThreadCallback = new Handler();
  private final int RESTART = 42;

  // This lil guy is used to inject operations that effect the UI into the event loop
  private final LetterAddingRunnable runInUIRunnable = new LetterAddingRunnable();

  // And he does the real legwork
  private BackgroundRunnable bgRunnable = null;

  private TextView tv;

  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    this.tv = new TextView(this);
    runInUIRunnable.setView(tv);
    start();
    setContentView(tv);
  }

  /** Called when the view is just about to be displayed */
  @Override
  public void onResume() {
    super.onResume();
  }


  /** (Re)initializes the fancy-schmancy Hello, Android and starts the background Thread */
  public void start() {
    if(this.bgRunnable != null) {
      this.bgRunnable.reset();
      runInUIRunnable.reset();
    }
    this.tv.setText(HELLO_COMMA_STR);

    this.bgRunnable = new BackgroundRunnable();
    Thread t = new Thread(this.bgRunnable);
    t.start();
  }


  /** Creates the Restart menu item */
  public boolean onCreateOptionsMenu(Menu menu) {
    menu.add(0, RESTART, 0, "Restart");
    return true;
  }

  /** Handles the Restart menu item selection */
  public boolean onOptionsItemSelected(MenuItem item) {
    if (item.getItemId() == RESTART) {
      start();
      return true;
    }
    return false;
  }

  class BackgroundRunnable implements Runnable {
    private  boolean stop = false;

    public void run() {
      for(String letter: LETTERS) {
        try {
          Thread.currentThread().sleep(1000);
          if(stop) break;
          runInUIRunnable.addLetter(letter);
        } catch(Exception e) {
        }
      }
    }

    public void reset() {
      stop = true;
    }
  }

  class LetterAddingRunnable implements Runnable {
    private String letter;
    private TextView tv;
    private StringBuffer buf = new StringBuffer(HELLO_COMMA_STR);

    public void reset() {
      buf.setLength(0);
      buf.append(HELLO_COMMA_STR);
    }

    public void setView(TextView tv) {
      this.tv = tv;
    }

    public void addLetter(String letter) {
      buf.append(letter);
      uiThreadCallback.post(this);
    }

    public void run() {
      tv.setText(buf.toString());
    }
  }
}

Thread.currentThread().sleep(1000); should just be written as Thread.sleep(1000); because sleep() is a static method