Full game tutorial - part 4. Scene management:

• BaseScene - this class will be a basic representation of each created scene in our game, it is an abstract class, which will handle basic scene logic.
• SceneManager - as you can conclude, this class will provide ways to manage our scenes, switching between them, keeping track of current scene, scene type etc.

1. BaseScene class:

package com.matimdev.base;

import org.andengine.engine.Engine;
import org.andengine.engine.camera.Camera;
import org.andengine.entity.scene.Scene;
import org.andengine.opengl.vbo.VertexBufferObjectManager;

import android.app.Activity;

import com.matimdev.manager.ResourcesManager;
import com.matimdev.manager.SceneManager.SceneType;

/**
 * @author Mateusz Mysliwiec
 * @author www.matim-dev.com
 * @version 1.0
 */
public abstract class BaseScene extends Scene
{
    //---------------------------------------------
    // VARIABLES
    //---------------------------------------------
    
    protected Engine engine;
    protected Activity activity;
    protected ResourcesManager resourcesManager;
    protected VertexBufferObjectManager vbom;
    protected Camera camera;
    
    //---------------------------------------------
    // CONSTRUCTOR
    //---------------------------------------------
    
    public BaseScene()
    {
        this.resourcesManager = ResourcesManager.getInstance();
        this.engine = resourcesManager.engine;
        this.activity = resourcesManager.activity;
        this.vbom = resourcesManager.vbom;
        this.camera = resourcesManager.camera;
        createScene();
    }
    
    //---------------------------------------------
    // ABSTRACTION
    //---------------------------------------------
    
    public abstract void createScene();
    
    public abstract void onBackKeyPressed();
    
    public abstract SceneType getSceneType();
    
    public abstract void disposeScene();
}

As previously mentioned, this will be our "core" class for every created scene. It will be used as an extension, providing basic scene logic, using abstract methods. It will also have the most commonly used objects taken from previously created ResourcesManager. There is getSceneType , returning SceneType - it will be an enum inside the SceneManager class, ignore the error and move to the next step below to create the scene manager.

2. SceneManager class:

package com.matimdev.manager;

import org.andengine.engine.Engine;

import com.matimdev.base.BaseScene;

/**
 * @author Mateusz Mysliwiec
 * @author www.matim-dev.com
 * @version 1.0
 */
public class SceneManager
{
    //---------------------------------------------
    // SCENES
    //---------------------------------------------
    
    private BaseScene splashScene;
    private BaseScene menuScene;
    private BaseScene gameScene;
    private BaseScene loadingScene;
    
    //---------------------------------------------
    // VARIABLES
    //---------------------------------------------
    
    private static final SceneManager INSTANCE = new SceneManager();
    
    private SceneType currentSceneType = SceneType.SCENE_SPLASH;
    
    private BaseScene currentScene;
    
    private Engine engine = ResourcesManager.getInstance().engine;
    
    public enum SceneType
    {
        SCENE_SPLASH,
        SCENE_MENU,
        SCENE_GAME,
        SCENE_LOADING,
    }
    
    //---------------------------------------------
    // CLASS LOGIC
    //---------------------------------------------
    
    public void setScene(BaseScene scene)
    {
        engine.setScene(scene);
        currentScene = scene;
        currentSceneType = scene.getSceneType();
    }
    
    public void setScene(SceneType sceneType)
    {
        switch (sceneType)
        {
            case SCENE_MENU:
                setScene(menuScene);
                break;
            case SCENE_GAME:
                setScene(gameScene);
                break;
            case SCENE_SPLASH:
                setScene(splashScene);
                break;
            case SCENE_LOADING:
                setScene(loadingScene);
                break;
            default:
                break;
        }
    }
    
    //---------------------------------------------
    // GETTERS AND SETTERS
    //---------------------------------------------
    
    public static SceneManager getInstance()
    {
        return INSTANCE;
    }
    
    public SceneType getCurrentSceneType()
    {
        return currentSceneType;
    }
    
    public BaseScene getCurrentScene()
    {
        return currentScene;
    }
}

There are also handy getters to receive current scene type and current scene references, which might be useful in your further game development stages. There is the most important method setScene(SceneType sceneType) which takes care about displaying another scene and keeping track of it, by storing references of the displayed scene and its type.

That`s all - our scene management system is ready to be used, quite simple isn't it? Now we move to the next step, creating our first scene, which is a splash screen. Go to next article!