小编Chl*_*rty的帖子

我班上有以下代码:

public static ArrayList<String[]> allCombos;

public static void main(String[] args){
    allCombos = new ArrayList<String[]>();
    String[] arr = {"A","B","C","D","E","F"};
    combinations(arr, 3, 0, new String[3]);

}

static void combinations(String[] arr, int len, int startPosition, String[] result){
    if (len == 0){
        allCombos.add(result);   // this is where the problem seems to be
        return;
    }      
    for (int i = startPosition; i <= arr.length-len; i++){
        result[result.length - len] = arr[i];
        combinations(arr, len-1, i+1, result);
    }
}       

出于某种原因,每次allCombos.add(result)调用时combinations(),该方法似乎将整个数组中的每个元素设置为结果的当前值,从而超过前一次迭代combinations()设置最近添加的allCombosas的值.如果allCombos …