无法解析java“”如何解决此错误？

Question

我是一个初学者，对Java的理解很差。我使用Dr.Java，我得到以下错误：

     "S cannot be resolved"

使用此Java程序：

import java.util.Scanner;

public class HDtest5

{
    public static int countWords(String str) {
        String words[] = str.split(" ");
        int count = words.length;
        return count;
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a sentence: ");
        String sentence = in.nextLine();
        System.out.print("Your sentence has " + countWords(sentence) + " words.");
    }

    {
        while (true) // have created infinite loop
        {

            if (s.equals("quit"))
            // if enterd value is "quit" than it comes out of loop

            {

                String[] words = s.split(" "); // get the individual words
                System.out.println("#words = " + words.length);
                for (int i = 0; i < words.length; i++)
                    System.out.println(s + "word[" + i + words[i] + " nchars = " + words[i].length());

            }
            System.out.println(s); // to Print string
            System.out.println(s.length()); // to print Entered string's length

        }
    }
}

是什么原因导致此错误消息？ 我认为所有名为“s”的字符串应该一起工作，没有任何问题。你能帮我找出它的毛病吗？非常感谢您的帮助，非常感谢

另外，更清楚的是，我的程序的目的是输出字符总数、每个单词的字符数以及在文本窗口（扫描仪）中输入的文本的单词数。代码应该可以很好地工作，除了这个“s”字符串问题，它使得代码块不能一起工作

Answer 1

您之所以会出现此错误，是因为您尚未声明任何变量，但您正在if条件中使用此变量。此外，您还错误地放置了{}大括号。 将主要方法更改为以下内容：

注意：您的程序正在infinte循环中运行

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    System.out.print("Enter a sentence: ");
    String s = in.nextLine();
    System.out.print("Your sentence has " + countWords(s) + " words.");

    while (true) // have created infinite loop
    {

        if (s.equals("quit"))
        // if enterd value is "quit" than it comes out of loop

        {

            String[] words = s.split(" "); // get the individual words
            System.out.println("#words = " + words.length);
            for (int i = 0; i < words.length; i++)
                System.out.println(s + "word[" + i + words[i]
                        + " nchars = " + words[i].length());

        }
        System.out.println(s); // to Print string
        System.out.println(s.length()); // to print Entered string's length

    }
}

Answer 2

我想我已经找到了你想要实现的目标并修复了你的代码：

import java.util.Scanner;

public class HDtest5

{
    public static int countWords(String str) {
        String words[] = str.split(" ");
        int count = words.length;
        return count;
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        while (true) // have created infinite loop
        {
            System.out.print("Enter a sentence: ");
            String sentence = in.nextLine();
            if (sentence.equals("quit")) {
                // if enterd value is "quit" than it comes out of loop
                break;
            }
            System.out.print("Your sentence has " + countWords(sentence) + " words.");

            String[] words = sentence.split(" "); // get the individual words
            System.out.println("#words = " + words.length);
            for (int i = 0; i < words.length; i++)
                System.out.println("word[" + i + "] = " + words[i] + " nchars = " + words[i].length());
            }
            System.out.println(sentence); // to Print string
            System.out.println(sentence.length()); // to print Entered string's length
        }
        in.close();
    }
}

Answer 3

您尚未在代码中声明s。在main()方法的开头写一些类似的东西，String s=null;，然后在以后的代码中给它一些值

Answer 4

在Java中，必须先声明一个变量，然后才能使用它

缺少如下代码行：

String s;

顺便说一句，正如其他人所注意到的，您可能希望使用sentence而不是s。可能的值"quit"将在sentence变量中

---

通过声明变量：

String personName;

你说编译器：

From now on, understand personName as a piece of memory capable of storing a String.

编译器将为您完成一项伟大的工作-它不会让您为personName分配任何其他内容（如int），如果您键入了一个错误并在某处写入personMame，您将立即发现它，并且不会很晚在运行时发现它，因为您不知道代码为什么不能工作，比如在JavaScript中

Answer 5

我想您应该使用sentence变量。 而且，对于while循环的每次迭代，您都不会读取变量

也许你想要更多这样的东西

public class HDtest5 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (true) { // have created infinite loop
            System.out.print("Enter a sentence: ");
            String sentence = in.nextLine();
            System.out.print("Your sentence has " + countWords(sentence) + " words.");

            if (sentence.equals("quit")) { // if enterd value is "quit" than it comes out of loop
                break;
            } else {
                String[] words = sentence.split(" "); // get the individual words
                System.out.println("#words = " + words.length);
                for (int i = 0; i < words.length; i++)
                    System.out.println(sentence + "word[" + i + words[i] + " nchars = " + words[i].length());

            }
            System.out.println(sentence); // to Print string
            System.out.println(sentence.length()); // to print Entered string's length

        }
        in.close();
    }

    private static int countWords(String str) {
        String words[] = str.split(" ");
        int count = words.length;
        return count;
    }
}