Java Scanner输入流关闭问题

问题描述：关闭第一个Scanner输入流，第二个Scanner输入流异常

无异常代码

public static void test() {
        boolean f1 = true;
        boolean f2 = true;
        boolean f3 = true;
        int up = 0, down = 0, high = 0;
        double area = 0.0;
        System.out.println("-------");
        System.out.println("求梯形面积");
        System.out.println("-------");
        while (f1) {// 保证输入数据正确
            try {
                System.out.println("梯形上低：");
                Scanner in = new Scanner(System.in);
                up = in.nextInt();
                if (up <= 0) {// 几何图形边长大于0
                    System.out.println("数据值异常！");
                    continue;
                }
            } catch (InputMismatchException e) {
                System.out.println("数据类型异常");
                continue;
            }
            f1 = false;
        }

        while (f2) {
            try {
                System.out.println("梯形下低：");
                Scanner in = new Scanner(System.in);
                down = in.nextInt();
                if (down <= 0) {
                    System.out.println("数据异常！");
                    continue;
                }
            } catch (InputMismatchException e) {
                System.out.println("数据类型异常");
                continue;
            }
            f2 = false;
        }

        while (f3) {
            try {
                System.out.println("梯形高：");
                Scanner in = new Scanner(System.in);
                high = in.nextInt();
                if (high <= 0) {
                    System.out.println("数据异常！");
                    continue;
                }
            } catch (InputMismatchException e) {
                System.out.println("数据类型异常");
                continue;
            }
            f3 = false;
        }
        area = (up + down) * high / 2.0;//梯形面积
        System.out.println("梯形面积：" + area);

    }
    ...
}
...

添加in.close()后，代码出现异常
异常代码片段

public static void test() {
        ...
        while (f1) {// 保证输入数据正确
            try {
                ...
                Scanner in = new Scanner(System.in);
                ...
                in.close();//添加这句话后，下面读取输入流出现异常
            } catch (InputMismatchException e) {
                ...
            }
            ...
        }

        while (f2) {
            try {
                ...
                Scanner in = new Scanner(System.in);
                down = in.nextInt();//抛出异常：NoSuchElementException
                ...
            } catch (InputMismatchException e) {
                ...
            }
            ...
        }

问题出在哪里？

一般关闭应该放在finally关闭，
try{
}catch（..）{
}finally{
in.close;
}

因为你在while的时候f1上已经关闭了呀。后面再调用nextInt就报会错了