我有以下代码:

Integer[] lastExchange = new Integer[nColors];
Integer[] newExchange = new Integer[nColors];
while (true) {
    ...
    for (int i=0; i<nColors; i++) {
       lastExchange[i] = newExchange[i];
    }
    ...
    exchanges.add(lastExchange);
    output.log.fine("Exchange:" + lastExchange[0] + "," + lastExchange[1]);
}
for (Integer[] exchange : exchanges) {
    output.log.fine("Exchange:" + exchange[0] + "," + exchange[1]);
}


我有两个输出(一个在while循环中,另一个在for循环中)。第一个输出显示我确实向列表添加了不同的数组。当我在第二个循环中仔细检查时,我看到exchange列表的所有元素都相同(它们等于列表的第一个元素)。

有人知道我在这里做错了吗?

最佳答案

作为解开答案的状态,您将在循环的每次迭代中添加对同一数组的引用。您每次需要创建一个新数组:

// It's not clear where newExchange is actually populated
Integer[] newExchange = new Integer[nColors];
while (true) {
    Integer[] lastExchange = new Integer[nColors];
    ...
    for (int i=0; i<nColors; i++) {
       lastExchange[i] = newExchange[i];
    }
    ...
    exchanges.add(lastExchange);
    output.log.fine("Exchange:" + lastExchange[0] + "," + lastExchange[1]);
}


另外,如果您只是克隆数组:

Integer[] newExchange = new Integer[nColors];
while (true) {
    Integer[] lastExchange = newExchange.clone();
    ...
    exchanges.add(lastExchange);
    output.log.fine("Exchange:" + lastExchange[0] + "," + lastExchange[1]);
}

10-05 20:53
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