使用hasnext（）无法通过无限循环 [英] Can't get past the infinite while loop using hasnext()

问题描述

我编写的程序计算字符串用户输入中的大写和小写字母的数量。我知道hasNext（）不会超过输入，但我有input.next（）来推进。还有一个无限循环。



我尝试过：

Hi,
The program I wrote counts the # of upper and lowercase letters in a string user inputs. I know that hasNext() does not advance past the input, but I have input.next() to advance. Still there is an infinite loop.

What I have tried:

public class CountLetters {
    public static void main(String[] arg) {
        int[] lower = new int[26];
        int[] upper = new int[26];

        for(int i = 0; i < 26; i++)
            lower[i] = upper[i] = 0;
        Scanner input = new Scanner(System.in);
        System.out.print("Enter the string: ");

        while(input.hasNext()) {
            String temp = input.next();
            for (int i = 0; i < temp.length(); i++) {
                char c = temp.charAt(i);
                if (Character.isUpperCase(c))
                    upper[(int) c - 65]++;
                if (Character.isLowerCase(c))
                    lower[(int) c - 97]++;
            }
            input.next();
        }
        System.out.print("a is " + lower[0]);
        System.out.print("A is " + upper[0]);
    }
}

推荐答案

请参阅以下链接：

See the following link:

无关错误？

丢弃是否正常输入的一部分

Unrelated bug ?
Is it normal to discard part of the input with

input.next();

循环中的
？

in the loop ?

输入中没有任何内容可以丢弃。我尝试在点击输入后添加一个ctrl + D并且它有效。显然，这是使hasNext为false的唯一方法。

No nothing in the input can be discarded. I tried adding a ctrl+D after hitting enter and it worked. Apparently that is the only way to make hasNext false.

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