Java HashMap 计算数组条目

Question

我如何使用 HashMap 来计算此数组中唯一条目的数量：

import java.util.Scanner;

public class Entry {

    private Scanner scan = new Scanner(System.in);


public void userInput(){
Scanner scan = new Scanner(System.in);
System.out.println("Please tell me the amount of numbers you will be entering (Up to 50): ");
        int [] arr = new int[scan.nextInt()];      

        for(int i=0;i<arr.length; i++) {
            scan = new Scanner(System.in);
            System.out.println("Please enter a number: ");
            while(scan.hasNextInt()){
            int x = scan.nextInt();
            arr[i]= x;
            break;
            }
        }        

         System.out.println(" ");
         System.out.println("Results of Data Entry");
         System.out.println("_____________________");
         for(int i:arr){System.out.println(i + " occurs "); 
        }
} 
}

我想输出以显示输入的数字以及输入的次数。

所以如果我输入 1 5 6 6 7

它会显示

1 occurs 1
5 occurs 1
6 occurs 2
7 occurs 1

Answer 1

List asList = Arrays.asList(array);
Set<String> mySet = new HashSet<String>(asList);
for(String s : mySet) {
    System.out.println(s + " " + Collections.frequency(asList, s));
}