【问题标题】:For-loop gives only one value when iterating through an array of Vectors (libGDX)遍历向量数组(libGDX)时,for循环仅给出一个值
【发布时间】:2015-06-04 12:42:02
【问题描述】:

我只是一个初学者,所以这可能是一些我可以识别的小错误,但是是的......我正在使用 libGDX 库,这是我的方法的代码:

public Vector2[] initCollisionStart() {

    int i = 0;

    for (int row = 0; row < currentMapHeightTiles; row++) {
        for (int col = 0; col < 9; col++) {
            if (currentMap[row][col] == 4) {
                i++;
            } else if (currentMap[row][col] == 3) {
                i++;
            }
        }
    }

    Gdx.app.log("initCollisionStart", "works");

    Vector2[] collisionStart = new Vector2[i];

    for (int row = 0; row < currentMapHeightTiles; row++) {
        for (int col = 0; col < 9; col++) {
            if (currentMap[row][col] == 4) {
                position.x = col * 40;
                position.y = row * 40;
                collisionStart[i - 1] = position;
                System.out.println("CollisionStart[" + i + "] = " + collisionStart[i - 1]);
                i--;
            } else if (currentMap[row][col] == 3) {
                position.x = col * 40;
                position.y = row * 40;
                collisionStart[i - 1] = position;
                System.out.println("CollisionStart[" + i + "] = " + collisionStart[i - 1]);
                i--;
            }
        }
    }

    collisionInitialized = true;
    System.out.print("\n");
    for (int z = 0; z < collisionStart.length; z++) {
        System.out.println("CollisionStart[" + z + "] = " + collisionStart[z]);
    }
    return collisionStart;
}

我的输出看起来像这样:

initCollisionStart: works
CollisionStart[7] = [40.0:5760.0]
CollisionStart[6] = [80.0:5760.0]
CollisionStart[5] = [120.0:5760.0]
CollisionStart[4] = [160.0:5760.0]
CollisionStart[3] = [200.0:5760.0]
CollisionStart[2] = [240.0:5760.0]
CollisionStart[1] = [280.0:5760.0]

CollisionStart[0] = [280.0:5760.0]
CollisionStart[1] = [280.0:5760.0]
CollisionStart[2] = [280.0:5760.0]
CollisionStart[3] = [280.0:5760.0]
CollisionStart[4] = [280.0:5760.0]
CollisionStart[5] = [280.0:5760.0]
CollisionStart[6] = [280.0:5760.0]

这是我的问题。当我在这个双 for 循环之外使用它时,为什么这个 collisionStart 数组的每个值都等于 [280.0:5760.0]?我希望它返回之前初始化的相同值。有没有办法做到这一点?

提前感谢您的帮助

【问题讨论】:

  • 顺便说一句,ifelse if 中的行看起来完全一样。你确定它应该是这样的吗?

标签: java arrays for-loop libgdx


【解决方案1】:

在你的第二个双循环中

 collisionStart[i - 1] = position;

应该改为

collisionStart[i - 1] = new Vector2(...);

我不确定你从哪里获得职位。
但我假设它是您分配给 Vector2 数组的每个元素的某个 Vector2。
整个数组指向同一个对象,因此您的输出在 for 循环之外。

【讨论】:

  • 谢谢,没有意识到我必须初始化每个 Vector 对象。
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