CommandPatternJavaVideoGame.java

// Receiver
class Entity {
    String name;
    public Entity(String name){
        this.name = name;
    }
    public void jump(){
        System.out.println(name + " Jump");
    }  
    public void fire(){
        System.out.println(name + " Fire");
    }
}

// Command interface
interface ICommand {
    public void execute(Entity entity);
}

// Concrete command
class JumpCommand implements ICommand {
    public void execute(Entity entity){
        entity.jump();
    }
}

class FireCommand implements ICommand {
    public void execute(Entity entity){
        entity.fire();
    }
}

// Invoker
class InputHandler {
    static boolean xPressed = false;
    static boolean yPressed = false;
    
    // Commands
    ICommand jumpCommand = new JumpCommand();
    ICommand fireCommand = new FireCommand();
    
    public ICommand handleInput(){
        if(xPressed) {
            xPressed = false;
            return jumpCommand;
        }
        else if(yPressed) {
            yPressed = false;
            return fireCommand;
        }
        
        // nothing pressed
        return null;
    }
}

// Client
public class Game {
    public static void main(String args[]) {
        // Receivers
        Entity player = new Entity("Player");
        Entity enemy = new Entity("Enemy");
        
        InputHandler inputHanler = new InputHandler(); // Invoker
        
        InputHandler.xPressed = true; // press x button
        ICommand command = inputHanler.handleInput(); 
        
        if(command != null){
            command.execute(player);
            command.execute(enemy);
            command.execute(enemy);
        }
        
        InputHandler.yPressed = true; // press y button
        command = inputHanler.handleInput();
        
        if(command != null){
            command.execute(player);
            command.execute(enemy);
            command.execute(enemy);
        }
    }
}