变化值变化原因不明？

Question

我应该知道这个,但为什么这会openPos[1]变为0？我知道它必须做与startPos[1] = 0在findCloseCurlBracket()方法,但为什么它做它没有意义.

int[] openPos = {1, 26};
    System.out.println(openPos[0]+", "+openPos[1]);
    int[] closePos = LuaTableParser.findCloseCurlBracket(stringList, openPos);
    System.out.println(openPos[0]+", "+openPos[1]);

findCloseCurlBracket()方法:

public static int[] findCloseCurlBracket(List<String> text, int[] openPos) {
    int[] startPos = openPos;
    int counter = 1;
    for(int line = startPos[0]; line < text.size(); line++){
        for(int index = startPos[1]; index < text.get(line).length()-startPos[1]; index++){
            int[] curPos = {line, index};
            if(getStringListCharAt(text, curPos) == '{'){
                counter++;
            }else if(getStringListCharAt(text, curPos) == '}'){
                counter--;
            }
            if(counter == 0){
                startPos[1] = 5;
                return curPos;
            }
        }
        startPos[1] = 0;
    }
    return null;
}

Answer 1

startPos如所指的在同一阵列openPos二者的事情是:引用到一个阵列的int第

int[] startPos = openPos;并没有采取的深层副本openPos.

您的写作startPos[1] = 5;正在更改openPos调用者中引用的同一数组中的元素findCloseCurlBracket.

深度复制的一种方法是写int[] startPos = openPos.clone();.

Answer 2

因为openPos是对(指向)数组的引用.您将该引用(不是数组,对它的引用)复制为findCloseCurlBracketas openPos.然后你将这个引用复制到startPos所以现在openPos变量,openPos参数和startPos变量都指向内存中的同一个数组:

+-------------------+
| openPos variable  |--+
+-------------------+  |
                       |
+-------------------+  |     +-----------+
| openPos argument  |--+---->| the array |
+-------------------+  |     +-----------+
                       |     | 0: 1      |
+-------------------+  |     | 1: 26     |
| startPos variable |--+     +-----------+
+-------------------+

然后你这样做:

startPos[1] = 5;

...修改数组:

+-------------------+
| openPos variable  |--+
+-------------------+  |
                       |
+-------------------+  |     +-----------+
| openPos argument  |--+---->| the array |
+-------------------+  |     +-----------+
                       |     | 0: 1      |
+-------------------+  |     | 1: 5      |
| startPos variable |--+     +-----------+
+-------------------+

无论您使用什么引用,当您修改这些引用所指向的状态时,您都可以看到通过所有引用进行更改.

如果您不想共享阵列,则需要复制它,正如Bathsheba在她的回答(+1)中所示:

int[] startPos = openPos.clone();