CRASH：com.badlogic.gdx.physics.box2d.World.jniCreateBody

Question

尝试我的游戏，当我从Java运行时环境EXCEPTION_ACCESS_VIOLATION崩溃。它与LibGdx书面（并使用Box2D的）。它是从机器人工作室的桌面模式下运行。

我加了一个“火球”功能，我supermario游戏，并跳进空气和拍摄火球时出现此错误。这里是崩溃日志：

的Java帧：（J =编译的Java代码，J =解释，VV = VM代码）.J com.badlogic.gdx.physics.box2d.World.jniCreateBody（JIFFFFFFFFZZZZZF）J +为0J com.badlogic.gdx.physics.box2d。 World.createBody（LCOM / badlogic / GDX /物理/ Box2D的/ BodyDef）LCOM / badlogic / GDX /物理/ Box2D的/身体; 80Ĵcom.mygdx.game.sprite.Fireball.define（）V + 68ĴCOM .mygdx.game.sprite.Fireball（LCOM / mygdx /游戏/屏幕/播放屏幕; FFZ）。V + 135Ĵcom.mygdx.game.sprite.Mario.shootFire（）V + 36架J 1115 C1 com.mygdx.game .screen.PlayScreen.handleInput（F）V（221个字节）@ 0x000000000320f90c [0x000000000320e960 + 0xfac：J 1073 C1 com.mygdx.game.screen.PlayScreen.update（F）V（188个字节）@ 0x00000000031e14ec [0x00000000031e1440 + 0xac] Ĵ1074 C1 com.mygdx.game.screen.PlayScreen.render（F）V（252个字节）@ 0x00000000031e493c [0x00000000031e3f20 + 0xa1c：J 1223 C1 com.mygdx.game.MarioBros.render（）V（5个字节）@ 0x0000000003263ae4 [0x0000000003263920 + 0x1c4：J com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop（）V + 698Ĵcom.badlogic.gdx.backends.lwjgl.LwjglApplic通货膨胀$ 1.run（）V + 27 V〜StubRoutines :: call_stub

这里是我的火球类：

public class Fireball extends Sprite {

private PlayScreen playScreen;
private World world;
private Array<TextureRegion> frames;
private Animation<TextureRegion> animation;
private float stateTimer;
private boolean destroyed;
private boolean destroy;
private boolean fireToRight;
private Body body;

public Fireball(PlayScreen playScreen, float x, float y, boolean fireToRight){
    this.playScreen = playScreen;
    this.fireToRight = fireToRight;
    this.world = playScreen.getWorld();
    destroy = false;
    destroyed = false;
    frames = new Array<TextureRegion>();
    for(int i = 0; i < 4; i++)
        frames.add(new TextureRegion(playScreen.getAtlas().findRegion("fireball"),i*8,0,8,8));
    animation = new Animation<TextureRegion>(0.2f, frames);
    setRegion(animation.getKeyFrame(0));
    setBounds(x, y, 6/ C.PIXEL_PER_METER, 6/C.PIXEL_PER_METER);
    define();
}

private void define(){
    BodyDef bodyDef = new BodyDef();
    bodyDef.position.set(fireToRight ? getX() + 12 /C.PIXEL_PER_METER : getX() - 12 /C.PIXEL_PER_METER, getY());
    bodyDef.type = BodyDef.BodyType.DynamicBody;
    if(world.isLocked())
        return;
    body = world.createBody(bodyDef);
    FixtureDef fixtureDef = new FixtureDef();
    CircleShape shape = new CircleShape();
    shape.setRadius(3 / C.PIXEL_PER_METER);
    fixtureDef.filter.categoryBits = C.FIREBALL_BIT;
    fixtureDef.filter.maskBits = C.GROUND_BIT |
            C.COIN_BIT |
            C.BRICK_BIT |
            C.ENEMY_BIT |
            C.OBJECT_BIT;
    fixtureDef.shape = shape;
    fixtureDef.restitution = 1;
    fixtureDef.friction = 0;
    body.createFixture(fixtureDef).setUserData(this);
    body.setLinearVelocity(new Vector2(fireToRight ? 2 : -2, 2.5f));
}

public void update(float deltaTime){
    if((stateTimer > 3 || destroy) && !destroyed){
        world.destroyBody(body);
        destroyed = true;
        body = null;
        return;
    }

    stateTimer += deltaTime;
    setRegion(animation.getKeyFrame(stateTimer, true));
    setPosition(body.getPosition().x - getWidth()/2, body.getPosition().y - getHeight()/2);

    if(body.getLinearVelocity().y > 2f)
        body.setLinearVelocity(body.getLinearVelocity().x,2f);
    if((fireToRight && body.getLinearVelocity().x < 0 ) || (!fireToRight && body.getLinearVelocity().x > 0))
        destroy();
}

public void destroy(){
    destroy = true;
}

public boolean isDestroyed(){
    return destroyed;
}

}

我叫mario.shootFire()从播放屏幕类。

这就是“马里奥拍摄火球”：

private Array<Fireball> fireballs;

fireballs = new Array<Fireball>();

 public void shootFire(){
        fireballs.add(new Fireball(playScreen, body.getPosition().x, body.getPosition().y, runRight));
    }

    @Override
    public void draw(Batch batch) {
        super.draw(batch);
        for (Fireball fireball: fireballs)
            fireball.draw(batch);
    }

为什么我得到这个错误任何想法？

编辑：现在看来似乎崩溃在这条线body = world.createBody(bodyDef)中定义火球（）方法。

Answer 1

com.badlogic.gdx.physics.box2d.World.jniCreateBody

您试图访问内存不再可用。对于如何创建和销毁Box2D的几个机构教程。您有关于做在正确的时间，以更新物理世界（步骤（））。

既然你只能得到JNI调试信息是非常难以知道确切位置是（去过那里很多次）的错误的一个好方法，以获得更好的例外是对身体设置为null（右后world.destroyBody（身体）;）

world.destroyBody(body);
body = null;
destroyed = true;