Java中生成不重复随机数的四种方法举例详解

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

public class ShuffleDemo {
    public static void main(String[] args) {
        int min = 1, max = 100;
        List<Integer> numbers = new ArrayList<>();
        for (int i = min; i <= max; i++) {
            numbers.add(i);
        }
        Collections.shuffle(numbers); // 关键：随机打乱顺序
        
        // 获取前10个不重复值
        numbers.stream().limit(10).forEach(System.out::println);
    }
}

import java.util.HashSet;
import java.util.Random;
import java.util.Set;

public class SetDemo {
    public static void main(String[] args) {
        int min = 1, max = 100_000, count = 10;
        Set<Integer> uniqueNumbers = new HashSet<>();
        Random random = new Random();

        while (uniqueNumbers.size() < count) {
            int num = random.nextInt(max - min + 1) + min;
            uniqueNumbers.add(num); // Set自动去重
        }

        uniqueNumbers.forEach(System.out::println);
    }
}

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

public class PoolDemo {
    public static void main(String[] args) {
        int min = 1, max = 1000, count = 10;
        List<Integer> pool = new ArrayList<>();
        for (int i = min; i <= max; i++) {
            pool.add(i);
        }

        Random random = new Random();
        for (int i = 0; i < count; i++) {
            int index = random.nextInt(pool.size());
            int num = pool.remove(index); // 移除已选值
            System.out.println(num);
        }
    }
}

import java.util.Random;
import java.util.stream.IntStream;

public class StreamDemo {
    public static void main(String[] args) {
        int min = 1, max = 100, count = 10;
        Random random = new Random();

        IntStream.generate(() -> random.nextInt(max - min + 1) + min)
                .distinct()     // 去重
                .limit(count)   // 限制数量
                .forEach(System.out::println);
    }
}