随机化方法的问题(Issue with randomize method)

 我有一个方法无法正常工作。 该方法应该随机地将一组数字从1到20排序（每个数字必须只出现一次）。 我的问题是，当我运行程序时，一些数字会重复多次。 代码如下： 
 
public static int randomize(int index) {

    //This array will hold the 20 numbers.
    int[] randomIndex = new int[20];

    Random ranNum = new Random();

    for (int x = 0; x<20; x++) {
        int temp;

        //The number is generated randomly and saved in temp.
        temp = ranNum.nextInt(20);

        //This loop skips the first index.
        if (x != 0){

            /*Here, the loop is supposed to compare a generated number with
            the previous one*/
            for (int y = 1; y<=x; y++) {


                while(temp == randomIndex[x-y] ) {

                    /*If the while loop finds that temp variable matches any previous                          
                    number it will generate another random number for it until it finds
                    no matches.*/
                    temp = ranNum.nextInt(20);

                }  
            }
        }

    /*Once no match has been found for temp, the number is assigned to an index, 
    and the loop is executed with a x variable increment.
    randomIndex[x] = temp;

    }
   //Finally the array with the set of random numbers is sent to the main function.
   return randomIndex[index];

  }
 
 我得到以下输出： 
 
19, 19, 5, 16, 6, 2, 18, 1, 15, 1, 5, 19, 11, 4, 18, 0, 5, 18, 10.
 
 所以现在我不知道该怎么做。 ：C 

I have a method that is not working properly. The method is supposed to sort a set of numbers from 1 to 20 randomly (each number must appear just once). My issue here is that when I run the program, some numbers are repeated several times. The code is the following:
 
public static int randomize(int index) {

    //This array will hold the 20 numbers.
    int[] randomIndex = new int[20];

    Random ranNum = new Random();

    for (int x = 0; x<20; x++) {
        int temp;

        //The number is generated randomly and saved in temp.
        temp = ranNum.nextInt(20);

        //This loop skips the first index.
        if (x != 0){

            /*Here, the loop is supposed to compare a generated number with
            the previous one*/
            for (int y = 1; y<=x; y++) {


                while(temp == randomIndex[x-y] ) {

                    /*If the while loop finds that temp variable matches any previous                          
                    number it will generate another random number for it until it finds
                    no matches.*/
                    temp = ranNum.nextInt(20);

                }  
            }
        }

    /*Once no match has been found for temp, the number is assigned to an index, 
    and the loop is executed with a x variable increment.
    randomIndex[x] = temp;

    }
   //Finally the array with the set of random numbers is sent to the main function.
   return randomIndex[index];

  }
 
And I got the following output:
 
19, 19, 5, 16, 6, 2, 18, 1, 15, 1, 5, 19, 11, 4, 18, 0, 5, 18, 10.
 
So now I have no idea what to do. :C

原文：https://stackoverflow.com/questions/21419911