编写多线程程序

[qq_41335523]

编写多线程程序，创建 10 个线程，每个线程完成一个计算任务，各
个线程的计算任务是类似的：比如，从 1 加到 10(或从 1 乘到 10)，从
11 加到 20(或从 11 乘到 20)，…..，从 91 加到 100(或从 91 乘到 100)。
会用 for 循环创建这 10 个线程对象，用构造方法传入的参数来确定
各个线程的计算任务。

[java-小学生]

测试类：

public class Day0707 {
    public static void main(String[] args) {
        for (int i = 0, j = 1; i < 10 && j < 100; i++, j = j + 10) {
            Task task1 = new Task(j, j + 9, "+");
            Thread t = new Thread(task1);
            t.start();
        }
        for (int i = 0, j = 1; i < 10 && j < 100; i++, j = j + 10) {
            Task task1 = new Task(j, j + 9, "*");
            Thread t = new Thread(task1);
            t.start();
        }
    }
}

线程任务类：

public class Task implements Runnable {

    private int began;
    private int end;
    private String flag;

    public Task(int began, int end, String flag) {
        this.began = began;
        this.end = end;
        this.flag = flag;
    }

    @Override
    public synchronized void run() {
        if (flag.equals("+")) {
            int result = began;
            for (int i = began; i <= end; i++) {
                result = result + i;
            }

            System.out.println(Thread.currentThread().getName() + "..." + began + "..." + end + "..." + flag + "..." + result);
        } else if (flag.equals("*")) {
            Long result = (long) began;
            for (int i = began; i <= end; i++) {
                result = result * i;
            }
            System.out.println(Thread.currentThread().getName() + "..." + began + "..." + end + "..." + flag + "..." + result);
        }


    }
}

有问题请指出

[qq_41335523]

为什么结果都多加了一 怎么改