Main.java

package my.pkg.app;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import my.pkg.app.R;

public class Main extends Activity
{
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Button button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new OnClickListener() {
			public void onClick(View button) {
                TextView textView = (TextView) findViewById(R.id.textView);
                textView.setText("Good Bye World!");
			}
		});
    }
}