System.out.print 在 while 循环内不起作用

Question

我正在编写程序，您可以在其中不断输入数字，直到找到相邻的重复项，此时会显示消息“找到重复项”。 while 循环内部的 System.out.print 不会显示“请输入数字”消息。

package FindingDuplicates;

import java.util.Scanner;

public class FindingDuplicates {
    
    public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
        System.out.print("Please enter a number: ");
        double input = in.nextDouble();
        while(in.hasNextDouble())
        {
            double previous = input;
            System.out.print("Please enter a number: ");
            input = in.nextDouble();
            if(previous == input)
            {
                System.out.print("Duplicate found");
            }
        }
    }

}

Answer 1

您需要将第一个输入重新分配给前一个输入。

public class FindingDuplicates {
    
    public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
        System.out.print("Please enter a number: ");
        double previous = in.nextDouble();
        while(in.hasNextDouble())
        {
           
            System.out.print("Please enter a number: ");
            double input = in.nextDouble();
            if(previous == input)
            {
                System.out.println("Duplicate found");
            }
            previous = input;
        }
    }

}