import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.stream.Collectors;

public class Test0515 {
    public static void main(String[] args) {
        // 输出不重复的整数
        Scanner scanner = new Scanner(System.in);
        System.out.print("Please input the number:");
        int number = scanner.nextInt();
        System.out.print("Please input some integers:");
        List<Integer> numArr = new ArrayList<>();
        for(int i = 0;i < number;i++) numArr.add(scanner.nextInt());
        scanner.close();
        Map<Integer, Integer> map = numArr.stream().
                collect(Collectors.toMap(e->e, e->1, (e, e2)->e+e2));
        System.out.println(map);
        map.forEach((k,v)->{
            if(v==1)
                System.out.println(k);
        });
    }
}

Please input the number:
5
Please input some integers:1
2
2
3
4
{1=1, 2=2, 3=1, 4=1}
1
3
4

也可以11楼的统计计数的方式解决，详细的记录每个数字出现的次数
这里用的lambda表达式，也可以普通的遍历如

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Test0515 {
    public static void main(String[] args) {
        // 输出不重复的整数
        Scanner scanner = new Scanner(System.in);
        System.out.print("Please input the number:");
        int number = scanner.nextInt();
        System.out.print("Please input some integers:");
        Map<Integer, Integer> map = new HashMap<>();
        for(int i = 0;i < number;i++) {
            int inputVal = scanner.nextInt();
            if(map.get(inputVal) == null) {
                map.put(inputVal, 0);
            }
            map.put(inputVal, map.get(inputVal)+1);
        }
        scanner.close();
        System.out.println(map);
        map.forEach((k,v)->{
            if(v==1)
                System.out.println(k);
        });
    }
}