This is the gist for the "Extended Simple App" LibGDX tutorial found at: https://github.com/libgdx/libgdx/wiki/Extending-the-simple-game

Drop.java

package com.badlogic.drop;

import com.badlogic.gdx.Game;
import com.badlogic.gdx.graphics.g2d.BitmapFont;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;

public class Drop extends Game {

  	SpriteBatch batch;
	BitmapFont font;

	public void create() {
		batch = new SpriteBatch();
		// Use LibGDX's default Arial font.
		font = new BitmapFont();
		this.setScreen(new MainMenuScreen(this));
	}

	public void render() {
		super.render(); // important!
	}

	public void dispose() {
		batch.dispose();
		font.dispose();
	}

}

GameScreen.java

package com.badlogic.drop;

import java.util.Iterator;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Input.Keys;
import com.badlogic.gdx.Screen;
import com.badlogic.gdx.audio.Music;
import com.badlogic.gdx.audio.Sound;
import com.badlogic.gdx.graphics.GL10;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.math.MathUtils;
import com.badlogic.gdx.math.Rectangle;
import com.badlogic.gdx.math.Vector3;
import com.badlogic.gdx.utils.Array;
import com.badlogic.gdx.utils.TimeUtils;

public class GameScreen implements Screen {
  	final Drop game;

	Texture dropImage;
	Texture bucketImage;
	Sound dropSound;
	Music rainMusic;
	OrthographicCamera camera;
	Rectangle bucket;
	Array<Rectangle> raindrops;
	long lastDropTime;
	int dropsGathered;

	public GameScreen(final Drop gam) {
		this.game = gam;

		// load the images for the droplet and the bucket, 64x64 pixels each
		dropImage = new Texture(Gdx.files.internal("droplet.png"));
		bucketImage = new Texture(Gdx.files.internal("bucket.png"));

		// load the drop sound effect and the rain background "music"
		dropSound = Gdx.audio.newSound(Gdx.files.internal("drop.wav"));
		rainMusic = Gdx.audio.newMusic(Gdx.files.internal("rain.mp3"));
		rainMusic.setLooping(true);

		// create the camera and the SpriteBatch
		camera = new OrthographicCamera();
		camera.setToOrtho(false, 800, 480);

		// create a Rectangle to logically represent the bucket
		bucket = new Rectangle();
		bucket.x = 800 / 2 - 64 / 2; // center the bucket horizontally
		bucket.y = 20; // bottom left corner of the bucket is 20 pixels above
						// the bottom screen edge
		bucket.width = 64;
		bucket.height = 64;

		// create the raindrops array and spawn the first raindrop
		raindrops = new Array<Rectangle>();
		spawnRaindrop();

	}

	private void spawnRaindrop() {
		Rectangle raindrop = new Rectangle();
		raindrop.x = MathUtils.random(0, 800 - 64);
		raindrop.y = 480;
		raindrop.width = 64;
		raindrop.height = 64;
		raindrops.add(raindrop);
		lastDropTime = TimeUtils.nanoTime();
	}

	@Override
	public void render(float delta) {
		// clear the screen with a dark blue color. The
		// arguments to glClearColor are the red, green
		// blue and alpha component in the range [0,1]
		// of the color to be used to clear the screen.
		Gdx.gl.glClearColor(0, 0, 0.2f, 1);
		Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

		// tell the camera to update its matrices.
		camera.update();

		// tell the SpriteBatch to render in the
		// coordinate system specified by the camera.
		game.batch.setProjectionMatrix(camera.combined);

		// begin a new batch and draw the bucket and
		// all drops
		game.batch.begin();
		game.font.draw(game.batch, "Drops Collected: " + dropsGathered, 0, 480);
		game.batch.draw(bucketImage, bucket.x, bucket.y);
		for (Rectangle raindrop : raindrops) {
			game.batch.draw(dropImage, raindrop.x, raindrop.y);
		}
		game.batch.end();

		// process user input
		if (Gdx.input.isTouched()) {
			Vector3 touchPos = new Vector3();
			touchPos.set(Gdx.input.getX(), Gdx.input.getY(), 0);
			camera.unproject(touchPos);
			bucket.x = touchPos.x - 64 / 2;
		}
		if (Gdx.input.isKeyPressed(Keys.LEFT))
			bucket.x -= 200 * Gdx.graphics.getDeltaTime();
		if (Gdx.input.isKeyPressed(Keys.RIGHT))
			bucket.x += 200 * Gdx.graphics.getDeltaTime();

		// make sure the bucket stays within the screen bounds
		if (bucket.x < 0)
			bucket.x = 0;
		if (bucket.x > 800 - 64)
			bucket.x = 800 - 64;

		// check if we need to create a new raindrop
		if (TimeUtils.nanoTime() - lastDropTime > 1000000000)
			spawnRaindrop();

		// move the raindrops, remove any that are beneath the bottom edge of
		// the screen or that hit the bucket. In the later case we play back
		// a sound effect as well.
		Iterator<Rectangle> iter = raindrops.iterator();
		while (iter.hasNext()) {
			Rectangle raindrop = iter.next();
			raindrop.y -= 200 * Gdx.graphics.getDeltaTime();
			if (raindrop.y + 64 < 0)
				iter.remove();
			if (raindrop.overlaps(bucket)) {
				dropsGathered++;
				dropSound.play();
				iter.remove();
			}
		}
	}

	@Override
	public void resize(int width, int height) {
	}

	@Override
	public void show() {
		// start the playback of the background music
		// when the screen is shown
		rainMusic.play();
	}

	@Override
	public void hide() {
	}

	@Override
	public void pause() {
	}

	@Override
	public void resume() {
	}

	@Override
	public void dispose() {
		dropImage.dispose();
		bucketImage.dispose();
		dropSound.dispose();
		rainMusic.dispose();
	}

}

MainMenuScreen.java

package com.badlogic.drop;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Screen;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;

public class MainMenuScreen implements Screen {
        final Drop game;
	OrthographicCamera camera;

	public MainMenuScreen(final Drop gam) {
		game = gam;

		camera = new OrthographicCamera();
		camera.setToOrtho(false, 800, 480);

	}

	@Override
	public void render(float delta) {
		Gdx.gl.glClearColor(0, 0, 0.2f, 1);
		Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

		camera.update();
		game.batch.setProjectionMatrix(camera.combined);

		game.batch.begin();
		game.font.draw(game.batch, "Welcome to Drop!!! ", 100, 150);
		game.font.draw(game.batch, "Tap anywhere to begin!", 100, 100);
		game.batch.end();

		if (Gdx.input.isTouched()) {
			game.setScreen(new GameScreen(game));
			dispose();
		}
	}

	@Override
	public void resize(int width, int height) {
	}

	@Override
	public void show() {
	}

	@Override
	public void hide() {
	}

	@Override
	public void pause() {
	}

	@Override
	public void resume() {
	}

	@Override
	public void dispose() {
	}
}

MainMenuScreenScreen.java should be MainMenuScreen.java and, for some reason, I get some visibility problems for

SpriteBatch batch;
BitmapFont font;

Being in the same package, they should be visible to the other 2 classes, but Eclipse complains they are not. Lots of other errors when starting the app on a real device + big crash.

@AgostinoSturaro sorry about that, I've fixed the errors not relating to visibilty, as I can not reproduce that, and changed the file name.

Please feel free to email me sinistersnare@gmail dot com or go on IRC, they can help there.

Thanks for the examples! Definitely helped me understand how to get started with the framework. Here's my repo with mostly the same code: https://github.com/kevinlondon/java-libgdx-drop-example

Would you mind if I submitted a pull request to use named constants instead of some of the values such as 800, 64, etc?

@sinistersnare I forked your gist and made a few minor changes to visibility and indentation. Feel free to merge it back into this one.

https://gist.github.com/supersam654/453a5cf5e19973b9fb26

@sinistersnare Correct me if I'm wrong, but I believe you may have forgot to append super.dispose(); in the dispose method of class Drop. Doing so resolved issues I was having with your example.

@sinistersnare I forked the gist and fixed some minor bugs and readability issues. Please feel free to merge my fork into this one.

https://gist.github.com/TobLoef/42f1fd370426d9ebe511/

GameScreen.dispose never gets called, so resources used by it will never be disposed??

@sinistersnare GameScreen.dispose() wasn't called at all; calling super.dispose() in Drop.dispose() didn't help, I was getting these messages when closing desktop window:

AL lib: (WW) FreeDevice: (0x7f9185959a00) Deleting 4 Buffer(s)

Adding screen.dispose(); to Game.dispose() fixed this issue.

Hey I am a little new to java, I just wanted to know where the setScreen function used in Drop class like:
this.setScreen(new MainMenuScreen(this));

I want to know where it is defined...because i thought 'this' keyword calls functions of the self class itself...but there seems to be no such function.

The above code needs to make a call to GameScreen's dispose method. Add

this.getScreen().dispose();

inside Drop class's dispose method. Hence the last screen's dispose method will be called through Game class' dispose method.

Hi All,

How can i add stop and start button in this game screen?
Please help me.

Thanks,
Sumit