Java如何找出数组中重复的数字

import java.util.Scanner;
 
public class Main {
 public static void getRepeateNum( int[] num) { 
 int NumChange;
 System.out.println("重复数字是：");
 for(int index = 0; index < num.length; index++) {
  while(num[index] != index) {
  if(num[index] == num[num[index]]) {
   System.out.print(num[index]+" ");
   break;
  } else {
   NumChange = num[num[index]];
   num[num[index]] = num[index];
   num[index] = NumChange;
  } 
  }
 } 
 }
 
 public static void main(String[] args) {
 Scanner scanner = new Scanner(System.in);
 int[] num = new int[5];  //数组长度可以自己定义
 System.out.println("请输入一组数据：");
 for(int i = 0; i < 5; i++) {
  num[i] = scanner.nextInt();
 }
 getRepeateNum(num);
 }
 
}