Java数组:Java pass by reference and pass by value?

Question

我正在尝试反转位图数组，而不修改源数组。但问题是源数组也被颠倒了。我做错了什么还是我应该以其他方式做？感谢您的帮助。

private GalleryAdapter galleryAdapter;
private ReverseGalleryAdapter rGalleryAdapter;  

public void onCreate(Bundle savedInstanceState) {
    galleryAdapter = new GalleryAdapter(this, imageThumbnails, imagePaths,
            videoThumbnails, videoPaths);

    imagegrid.setAdapter(galleryAdapter);

    rGalleryAdapter = new ReverseGalleryAdapter(this, reverseBArray(videoThumbnails), reverseSArray(videoPaths),
            reverseBArray(imageThumbnails), reverseSArray(imagePaths));

    imagegrid2.setAdapter(rGalleryAdapter);
}

private Bitmap[] reverseBArray(Bitmap[] v){
    Bitmap[] bTemp;
    bTemp = v;
    int len = bTemp.length;
    Bitmap temp;
    for (int i = 0; i < len/2; i++)
    {
        temp = bTemp[i];
        bTemp[i] = bTemp[len-1 - i];
        bTemp[len-1 - i] = temp;
    }
    return bTemp;
}

private String[] reverseSArray(String[] s){
    String[] sTemp;
    sTemp =s;
    int len = sTemp.length;
    String temp;
    for (int i = 0; i < len/2; i++)
    {
        temp = sTemp[i];
        sTemp[i] = sTemp[len-1 - i];
        sTemp[len-1 - i] = temp;
    }
    return sTemp;
}

Answer 1

 Bitmap[] bTemp;
 bTemp = v;

当您执行此操作时，肯定会引用同一个数组，因为您没有在那里创建新数组。

同样的情况也发生在这里

  String[] sTemp;
    sTemp =s;

可能的解决方案:Make copy of array Java (建议阅读可能的方式后进行选择)。

我的建议来自Official docs :(参见复制数组部分)

The System class has an arraycopy() method that you can use to efficiently copy data from one array into another:

public static void arraycopy(Object src, int srcPos,
                             Object dest, int destPos, int length)