java - Java异常后重新提示

Question

我记得在 Python 中遇到过这个问题。这段 Java 代码是我计算三角形面积的 Python 代码的复制品。如果输入非数字值，我会捕获异常，但最终结果会出错。

private static float baseLength() {
    float baseLength = 0;
    Scanner user_input = new Scanner(System.in);
    try {
        while (baseLength <= 0) {
            System.out.print("Enter the base length of the triangle: ");
            baseLength = user_input.nextFloat();
            if (baseLength <=0) {
                System.out.println("Error. Plase enter a number higher than 0.");
            }
        }            
    } catch (InputMismatchException badChar) {   
        System.err.println("You have entered a bad value. Please try again");
        baseLength();
    }
    return baseLength;

它将从错误的数字中恢复，但不能从非数字的值中恢复。我仍然无法弄清楚确切的问题是什么。

Answer 1

您可以在 try/catch block 周围放置 while 循环来实现此目的:

private static float baseLength() {
    float baseLength = 0;
    Scanner user_input = new Scanner(System.in);
    while (baseLength <= 0) {
        try {
            System.out.print("Enter the base length of the triangle: ");
            baseLength = user_input.nextFloat();
            if (baseLength <= 0) {
                System.out.println("Error. Plase enter a number higher than 0.");
            }
        } catch (InputMismatchException badChar) {
            System.err.println("You have entered a bad value. Please try again");
        }
    }
    return baseLength;
}