为什么列表中的元素会自行修改？[重复]

Question

我想把一个数组的不同数组元素组合（排列）放到一个列表中。我通过for循环交换数组的第一个和最后一个元素，组合（排列）被添加到列表中。然后，第二个元素和最后一个元素之前的元素被交换并添加到列表中，依此类推。假设数组是arr[1,2,3,4,5,6,7]，添加到列表中的第一个元素将是arr[7,2,3,4,5,6,1]。第二个元素是arr[7,6,3,4,5,2,1]。但我最终得到的是列表中所有元素的arr[7,6,5,4,3,2,1]。

问题是添加到List中的元素也会随着数组的当前修改而相应地修改。我最终在List中得到了类似的数组元素。我想要的是不同的排列或元素组合不同的数组。你能帮帮我吗？

private List<Gate[]> generateSolutions(Gate[] solution) {
    List<Gate[]> sList= new ArrayList<>();
    int i, j;
    for (i = 0, j = solution.length - 1; i < solution.length / 2; i++, j--) {
        Gate temp;
        temp = solution[i];
        solution[i] = solution[j];
        solution[j] = temp;
        sList.add(solution);
    }
    return sList;
}

Answer 1

import java.util.ArrayList;
import java.util.List;

/**
 * Dev Parzival
 * Date : 27/10/2020 Time : 22:40
 * I have a confidence about my life that comes from standing tall on my own two feet.
 */
public class Permutation {
    public static void main(String[] args) {
        ArrayList<Integer> list = new ArrayList<>(10);

        //Make sure that the list has unique numbers
        for(int i=0;i<3;i++)
            list.add(i+1);

        int n =list.size();
        Permutation permutation = new Permutation();

        //Generater permutation
        permutation.permute(list, 0, n-1);
    }

    private void permute(ArrayList<Integer> list, int l, int r) {
        //When l is equal to one less than the length of the list we will display it.
        if (l == r)
            System.out.println(list);
        else{
            //The l valuse specifies which position we want to fix
            for (int i = l; i <= r; i++) {
                //After diciding the position we fix it by swapping it.
                swap(list,l,i);
                //Here we are fixing l+1 th number
                permute(list, l+1, r);
                //Swapping it back to its original position so initial order is maintained
                swap(list,l,i);
            }
        }
    }

    //Swap function will swap ith and jth numbers of the list
    private void swap(List<Integer> list, int i, int j) {
        int temp=list.get(i);
        list.set(i,list.get(j));
        list.set(j,temp);
    }

}

上述代码用于生成置换