java抢红包,写个多线程程序

Java抢红包是一个常见的多线程编程问题，下面是一个简单的示例程序：

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

public class RedPacket {
    private double totalAmount; // 红包总金额
    private int totalNum; // 红包总数量
    private List<Double> amounts; // 每个红包的金额

    public RedPacket(double totalAmount, int totalNum) {
        this.totalAmount = totalAmount;
        this.totalNum = totalNum;
        this.amounts = new ArrayList<>();
    }

    public synchronized double grab() {
        if (totalNum <= 0) {
            return 0;
        }
        if (totalNum == 1) {
            totalNum--;
            return totalAmount;
        }
        Random random = new Random();
        double max = totalAmount / totalNum * 2;
        double amount = random.nextDouble() * max;
        amount = amount < 0.01 ? 0.01 : amount;
        totalAmount -= amount;
        totalNum--;
        amounts.add(amount);
        return amount;
    }

    public static void main(String[] args) {
        double totalAmount = 100; // 红包总金额
        int totalNum = 10; // 红包总数量

        RedPacket redPacket = new RedPacket(totalAmount, totalNum);

        List<Thread> threads = new ArrayList<>();
        for (int i = 0; i < totalNum; i++) {
            Thread thread = new Thread(() -> {
                double amount = redPacket.grab();
                System.out.println(Thread.currentThread().getName() + " 抢到了 " + amount + " 元");
            });
            threads.add(thread);
            thread.start();
        }

        for (Thread thread : threads) {
            try {
                thread.join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        System.out.println("红包抢完了");
    }
}

上述程序中，`RedPacket`类表示一个红包，通过`synchronized`关键字保证了抢红包的线程安全性。`grab`方法用于抢红包，每个线程调用该方法可以获取一个随机金额的红包。在`main`方法中，创建了10个线程来同时抢红包，最后输出每个线程抢到的金额。