Java Scanner输入验证导致循环提前结束

Question

我用一个for循环填充一个双数组，这个循环运行用户在第4行输入的圈数。然而，正如我在我的图片中演示的：

我进入了3圈，问题提示了3次，但是我的数据验证消耗了我正在寻找的输入之一。

我该如何解决这个问题？我觉得这是很简单的事情。

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

        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.");
            }
        }

由于您正在运行for-loop，因此每次都会递增I(即使您的验证失败了)。

Answer 2

这很简单:为了确保您插入的是double而不是一圈，请将您的扫描仪输入行放入while循环中

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

这将无法提供for循环递增计数器，除非do-while的条件为false。

为了打印验证，还需要：

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