This Android program displays a simple "Hello World" message on the screen. It creates an activity called MainActivity that extends the base Activity class and overrides its onCreate and onCreateOptionsMenu methods. The onCreate method sets the content view to a layout resource, and the onCreateOptionsMenu method inflates a menu layout resource to display options.

1. PROGRAMA 1; HOLA MUNDO
package com.example.holamundo;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is
present.

2. getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}