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]);
}