libGDX best way to do Game States

Carry your relevant variables/screens in other's screen using constructors. For example.

//main class extending Game class of libgdx public class mygame extends Game { public String var1="i will use it in screen1"; public String var2="i will use it in screen2"; Screen1 scn1; //instantiating screen 1 Screen2 scn2; // instantiating screen 2 public void create() { scn1=new Screen1(this); //scn1 object will be associated with same instance of this class scn2=new Screen2(this); //scn2 object will be associated with same instance of this class setScreen(scn1); } public void render() { super.render(); //important! } public void dispose() { //dispose } } //Screen1 class public class Screen1 implements Screen{ mygame game; public Screen1(mygame mg) { game=mg; } @Override public void render(float delta) { System.out.println("using game class variable var1:"+game.var1); game.setScreen(game.scn2); //calling screen 1 } @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() {} } //Screen2 class public class Screen2 implements Screen{ mygame game; public Screen2(mygame mg) { game=mg; } @Override public void render(float delta) { System.out.println("using game class variable var2:"+game.var2); game.setScreen(game.scn1); //calling back screen 1 } @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() {} } 

Solution

An easy and efficient way to manage screens is by using an enum which stores multiple constants. This is useful as you can refer to each screen with a meaningful name such as MENU instead of assigning a numerical index. This is also advantageous to other solutions as it is much simpler than other built-in systems such as the Scene2D system and can also be used for 3D games and multi-purpose applications.

Example:

public enum Screen { MENU, IN-GAME, BATTLE, INVENTORY } private Screen screen = Screen.MENU; public void render() throws IllegalStateException { switch(screen) { case MENU: Menu.render(); break; //Other cases here default: throw new IllegalStateException(); } 

How do you manage your Screens? If you use com.badlogic.gdx.Game class, it just calls screen.hide() on the previous screen and screen.show() on the next screen.

/** Sets the current screen. {@link Screen#hide()} is called on any old screen, and {@link Screen#show()} is called on the new * screen, if any. * @param screen may be {@code null} */ public void setScreen (Screen screen) { if (this.screen != null) this.screen.hide(); this.screen = screen; if (this.screen != null) { this.screen.show(); this.screen.resize(Gdx.graphics.getWidth(), Gdx.graphics.getHeight()); } } 

So you should move your initialization to any other method than show() e.g. init()

public class MyGame extends Game { GameScreen gameScreen; BattleScreen battleScreen; public void create () { gameScreen = new GameScreen(); gameScreen.init(); battleScreen = new BattleScreen(); setScreen(gameScreen); } // when you need to show the BattleScreen setScreen(battleScreen); // when you need to show the GameScreen again with all loaded resources and states setScreen(gameScreen); }