tween

SpriteTween.java

public class SpriteTween implements TweenAccessor<Sprite> {

    public static final int ALPHA = 0;

    @Override
    public int getValues(Sprite target, int tweenType, float[] returnValues) {
        switch(tweenType) {
            case ALPHA:
                returnValues[0] = target.getColor().a;
                Gdx.app.log(ZombieRunner.LOG, "getValues");
                return 1;
            default:
                return 0;
        }

    }

    @Override
    public void setValues(Sprite target, int tweenType, float[] newValues) {
        switch(tweenType) {
            case ALPHA:
                target.setColor(1, 1, 1, newValues[0]);
                Gdx.app.log(ZombieRunner.LOG, "set Alpha");
                break;
        }

    }

}

SplashScreen.java:
public void show() {

        splashTexture = new Texture("data/splashscreen.png");
        splashTexture.setFilter(TextureFilter.Linear, TextureFilter.Linear);

        splashSprite = new Sprite(splashTexture);
        splashSprite.setColor(1, 1, 1, 0);
        splashSprite.setX(Gdx.graphics.getWidth() / 2- (splashSprite.getWidth() / 2));
        splashSprite.setY(Gdx.graphics.getHeight() / 2- (splashSprite.getHeight() / 2));

        batch = new SpriteBatch();

        Tween.registerAccessor(Sprite.class, new SpriteTween());
        manager = new TweenManager();

        TweenCallback cb = new TweenCallback() {

            @Override
            public void onEvent(int type, BaseTween<?> source) {
                tweenCompleted();

            }

        } ;

        Tween.to(splashSprite, SpriteTween.ALPHA, 2).target(1,0).ease(TweenEquations.easeInOutQuart).setCallback(cb).
        setCallbackTriggers(TweenCallback.COMPLETE).start(manager);
    }

    private void tweenCompleted() {

        Gdx.app.log(ZombieRunner.LOG, "Tween Complete");
        game.setScreen(new MainMenu(game));
    }