Question

我正试图为游戏制作启动画面。我搜索谷歌无济于事。我正在学习本教程here，这对他有用。我的代码有点不同，但看起来有点像他的。这是我的代码：

游戏类：

import org.newdawn.slick.*;
import org.newdawn.slick.state.*;

public class Game extends StateBasedGame {

public static final String gamename = "Life - Alpha";
public static int menu = 1;
public static int play = 2;
public static int splash = 0;

public Game(String gamename) {
    super(gamename);
}

public void initStatesList(GameContainer gc) throws SlickException {
    this.getState(menu).init(gc, this);
    this.getState(play).init(gc, this);
    this.enterState(0);
}

public static void main(String[] args) {

    AppGameContainer app;
    try {
        app = new AppGameContainer(new Game(gamename));
        app.setDisplayMode(800, 600, false);
        app.start();
    } catch (SlickException e) {
        e.printStackTrace();
    }

   }
}

菜单类：

import org.lwjgl.input.Mouse;
import org.newdawn.slick.*;
import org.newdawn.slick.state.*;

public class Menu extends BasicGameState {

public Menu(int state) {

}

public void init(GameContainer gc, StateBasedGame sbg) throws SlickException {

}

public void render(GameContainer gc, StateBasedGame sbg, Graphics g) throws SlickException {

    Image back = new Image("res/Back.png");
    g.drawImage(back, 0, 0);

    Image panel = new Image("res/Panel.png");
    g.drawImage(panel, 240, 100);

    Image logo = new Image("res/Life Alpha.png");
    g.drawImage(logo, 290, 130);

    Image playButton = new Image("res/Play.png");
    g.drawImage(playButton, 330, 310);

    Image exitButton = new Image("res/Exit.png");
    g.drawImage(exitButton, 330, 370);

}

public void update(GameContainer gc, StateBasedGame sbg, int delta) throws SlickException {     

    Input input = gc.getInput();
    int xpos = Mouse.getX();
    int ypos = Mouse.getY();

    if((xpos > 330 && xpos < 480) && (ypos > 250 && ypos < 290)) {
        if(input.isMousePressed(0)) {
            sbg.enterState(2);
        }
    }
}

public int getID() {
    return 0;
}

}

播放课程

import org.newdawn.slick.*;
import org.newdawn.slick.state.*;

public class Play extends BasicGameState {

public Play(int state) {

}

public void init(GameContainer gc, StateBasedGame sbg) throws SlickException {

}

public void render(GameContainer gc, StateBasedGame sbg, Graphics g) throws SlickException {

    Image back = new Image("res/Back.png");
    g.drawImage(back, 0, 0);

    Image panel = new Image("res/Panel2.png");
    g.drawImage(panel, 170, 100);

}

public void update(GameContainer gc, StateBasedGame sbg, int delta) throws SlickException {

}

public int getID() {
    return 1;
}

}

SPLASHSCREEN CLASS：

import org.newdawn.slick.GameContainer;
import org.newdawn.slick.Graphics;
import org.newdawn.slick.Image;
import org.newdawn.slick.SlickException;
import org.newdawn.slick.state.BasicGameState;
import org.newdawn.slick.state.StateBasedGame;

public class SplashScreen extends BasicGameState {

Image splash;

private int elapsedTime;
private final int DELAY = 3000;

public SplashScreen(int state) {

}

public void init(GameContainer gc, StateBasedGame sbg) throws SlickException {

    splash = new Image("res/SplashScreen.png");

}

public void render(GameContainer gc, StateBasedGame sbg, Graphics g) throws SlickException {

    g.drawImage(splash, 0, 0);

}

public void update(GameContainer gc, StateBasedGame sbg, int delta) throws SlickException {

    elapsedTime += delta;

    if(elapsedTime >= DELAY) {

        sbg.enterState(1);

    }

}

public int getID() {
    return 0;
}

}

我得到的错误是：

Sat Apr 27 22:48:01 EST 2013 INFO：Slick Build＃274

Sat Apr 27 22:48:01 EST 2013资料：LWJGL版本：2.8.5

Sat Apr 27 22:48:01 EST 2013 INFO：OriginalDisplayMode：1366 x 768 x 32 @ 60Hz

Sat Apr 27 22:48:01 EST 2013 INFO：TargetDisplayMode：800 x 600 x 0 @ 0Hz

Sat Apr 27 22:48:01 EST 2013 INFO：开始显示800x600

Sat Apr 27 22:48:01 EST 2013 INFO：使用Java PNG Loader = true

Sat Apr 27 22:48:01 EST 2013 INFO：控制器不可用

线程“main”中的异常java.lang.NullPointerException

at mms001.Game.initStatesList（Game.java:18）

at org.newdawn.slick.state.StateBasedGame.init（StateBasedGame.java:164）

at org.newdawn.slick.AppGameContainer.setup（AppGameContainer.java:390）

at org.newdawn.slick.AppGameContainer.start（AppGameContainer.java:314）

at mms001.Game.main（Game.java:29）

Answer 1

看起来这里可能存在一些问题。

我注意到你的Menu类返回0作为它的ID，SplashScreen类也是如此。我敢打赌，如果你将getID类的Menu更改为1，那将解决部分问题。

class Menu...
public int getID() {
    return 1;
}

您还需要更新Play类的getID方法以返回2。

class Play...
public int getID() {
    return 2;
}

一旦你这样做，他们将匹配你的主类中定义的静态字段。

然后将您的initStatesList方法更新为初始splash并输入menu州

public void initStatesList(GameContainer gc) throws SlickException {
    this.getState(splash).init(gc, this);
    this.getState(menu).init(gc, this);
    this.getState(play).init(gc, this);

    this.enterState(menu);
}

希望这有帮助。

我用slick2D Java无法解决这个问题

1 个答案: