Java - 如何在使用hasNext（）条件时突破？ [英] Java - How to break out of while with hasNext() condition?

问题描述

我正在编写一个简单的程序来计算一组数字的平均值。您使用 Scanner 获取数字，因此我使用而循环使用 .hasNext（） 作为条件。然而，循环是无限的。

I am writing a simple program to calculate the average of a set of numbers. You get the numbers using Scanner, so I am using while loop with .hasNext() as a condition. However the loop is infinite.

如果没有在输入中写一些像停止这样的字，是否有可能突破它？

Is it possible to break out of it without writing some certain word like "stop" in the input?

public class main {

    public static void main(String[] args){

        Scanner Input = new Scanner(System.in);
        int count = 0;
        int temp;
        int sum = 0;

        while(Input.hasNextInt()){

           count++;           

           temp = Input.nextInt();
           sum += temp;
           System.out.println(temp);
           System.out.println(count);           

        } // End of while

        double average = sum / count;
        System.out.println("The average is: " + average);

    } // End of method main

}

推荐答案

break; 语句可以起诉......嗯......突破迭代。通过迭代我的意思是你也可以从中获取，例如。

The break; statement can be sued to... well... break out of an iteration. And by iteration I mean you can get out of a for too, for example.

你必须定义WHEN你想要突破迭代，然后做这样的事情：

You have to define WHEN do you want to break out of the iteration and then do something like this:

while(Input.hasNextInt(Input)){
   if(condition())
       break;

   count++;           

   temp = Input.nextInt();
   sum += temp;
   System.out.println(temp);
   System.out.println(count);           

 }

否则，您可以创建一个辅助方法来定义是否迭代应继续进行，如下所示：

Otherwise, you can make an auxiliary method that defines if the iteration should keep on going, like this one:

private boolean keepIterating(Scanner in) {
    boolean someOtherCondition = //define your value here that must evaluate to false
                                 //when you want to stop looping
    return Input.hasNextInt() && someOtherCondition;
}

您必须在中调用的方法：

while(keepIterating()){

   count++;           

   temp = Input.nextInt();
   sum += temp;
   System.out.println(temp);
   System.out.println(count);           

}

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