Java 扫描器输入验证导致循环提前结束

Question

我正在用 for 循环填充双精度数组，循环运行用户在第 4 行输入的圈数。但是，正如我在图片中展示的那样：

我输入了 3 圈，问题提示了 3 次，但是我的数据验证吃掉了我正在寻找的输入之一。

我该如何解决这个问题？我觉得很简单。

import java.util.Scanner;
public class JK_FINALPRAC1 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("Time-Trial Statistics Program\n");
        System.out.println("This program will ask you to input split-times for each lap or length of a race. The ");
        System.out.println("program will then calculate some basic statistics from the split-times.\n");

        System.out.print("Enter the number of laps or lengths in the race: ");
        int arraySize = sc.nextInt();
        Double[] lapArray = new Double[arraySize];
        System.out.println("Now input the elapsed time (split time) in seconds for each lap/length of the race.");
        int index = 1;
        double currentNum = 0.0;
        for(int i=0;i<arraySize;i++){
            System.out.print("Time for lap or length #" + index + ": ");
            currentNum = sc.nextDouble();
            if(currentNum > 0 && currentNum < 61){
            lapArray[i] = currentNum;
            index++;
            }else if(currentNum<0 || currentNum >60){
            System.out.println("Invalid input! Time must be between 0 and 60.");
            }
        }

    }

Answer 1

这很简单：为了确保您插入了一个 double 而没有吃一圈，将您的扫描仪输入行放在一个 while 循环中

 do{
    double x = scanner.nextDouble(); 
 }while(x < 0 || x > 60);

除非 do-while 的条件为假，否则这不会提供 for-loop 递增计数器。

为了也打印验证：

 double x = scanner.nextLine();
 while( x < 0 || x > 60){
      //print message
      //scanner again
 }

Answer 2

        double currentNum = 0.0;
        while (index < arraySize) {
            System.out.print("Time for lap or length #" + (index + 1) + ": ");
            currentNum = sc.nextDouble();
            if (currentNum > 0 && currentNum < 61) {
                lapArray[index] = currentNum;
                index++;
            } else if (currentNum < 0 || currentNum > 60) {
                System.out.println("Invalid input! Time must be between 0 and 60.");
            }
        }

因为你是运行 for 循环，我每次都会递增（即使你的验证失败）。

Java 扫描器输入验证导致循环提前结束

Java Scanner input validation causing loop to end early

java

validation

for-loop

java.util.scanner