Question

我一直在互联网上搜索，似乎无法找到答案那么有谁知道如何阻止用户输入只允许数字的字母？

这是我的代码到目前为止的样子。

public static double payCalculator(double hours, double basePay)
{
    double totalPay; 
    double overTime = 8.00 * 1.5;
    while(hours < 0 | hours > 60) {
        System.out.println("Cannot work more than 60 hours a week");
        System.out.println("Hours Work?");
        hours = in.nextDouble();
    }
    while(basePay < 8) {
        System.out.println("Base Pay cannot be less than 8");
        System.out.println("Base Pay?");
        basePay = in.nextDouble();
    }
    if 
        (hours <= 40){
        totalPay = hours*basePay;
    }
    else {
        totalPay = ((hours - 40)*overTime) + (40*basePay);
    }
    return totalPay;

}
public static void main (String[] args) {

    System.out.println("Hours worked?");
    hours = in.nextDouble();
    System.out.println("Base Pay?");
    basePay = in.nextDouble();
    DecimalFormat df = new DecimalFormat("###.##");
    totalPay = payCalculator(hours, basePay);
    System.out.println("Total Pay is " + df.format(totalPay));       
}
}

感谢您的时间。

Answer 1

我假设你正在使用Scanner来接受输入。

您可以使用Scanner.hasNextDouble()验证它是否为数字，如果使用double方法将此扫描仪输入中的下一个标记解释为nextDouble()值，则返回true。扫描仪不会超过任何输入。

考虑这个例子，它会继续询问输入，除非用户提供了一个数字，

    Scanner sc = new Scanner(System.in);
    double dbl = 0.0;
    boolean isValid = false;
    while (isValid == false) {
        System.out.println("Input Number: ");
        // If input is number execute this,
        if (sc.hasNextDouble()) {
            dbl = sc.nextDouble();
            isValid = true;
            System.out.println("OK");
        }
        // If input is not a number execute this block, 
        else {
            System.out.println("Error! Invalid number. Try again.");
        }
        sc.nextLine(); // discard any other data
    }
    sc.close();

<强>输出，

Input Number: 
adsads
Error! Invalid number. Try again.
Input Number: 
sdas
Error! Invalid number. Try again.
Input Number: 
hello
Error! Invalid number. Try again.
Input Number: 
hi
Error! Invalid number. Try again.
Input Number: 
2.0
OK

如何将用户输入限制为数值？

1 个答案: