Java

Question

averageLength获取用户在上一个案例中输入的所有单词，并获取平均单词量。 switch 语句位于 main 方法下（此处未显示）但是当我尝试实现案例 3 以获取平均值时，它不起作用，因为 average 未在 main 方法下声明，它在averageLength。我怎样才能解决这个问题？谢谢

    import java.util.Scanner;
    import java.util.Arrays;

    /**
     * Word Manager
     *
     * @author Harry
     */
    public class WordManager {

    /**
     * Adds the word to the next empty space in the array, if there is space.
     * Returns the new size of the array.
     */
    public static int add(String[] words, int count, String word) {

        if (count < words.length) {
            words[count] = word;
            count++;
        } else {
            System.out.println("The array is full");
        }
        return count;
    }

    /** Displays the words in the collection as a comma separated list. */
    public static void printList(String[] words, int count) { 
    }

    public static void averageLength(String[] words, int count) {
        Scanner sc = new Scanner(System.in);
        double average;
        double sum;

        while (sc.hasNext()) {
            String userInput = sc.next();

            double charNum = userInput.length();
            sum = charNum + sum;
            count++;

            if (count > 0) {
                average = sum / count;
                System.out.println("Average word length = " + average);

            }
        }

    }
    public static void main(String[] args ) {
        Scanner sc = new Scanner(System.in);
        String[] words = new String[20];
        int count = 0;
        String aWord;
        int choice;

        do {
            System.out.println("\t MENU:");
            System.out.println("1. Add a word");
            System.out.println("2. Display words:");
            System.out.println("3. Display average word length");
            System.out.println("4. Quit");
            System.out.println("Enter option: ");
            choice = sc.nextInt();
            System.out.println("choice = "+choice);

            switch (choice) {
                case 1: 
                    System.out.println("Add a word");
                    aWord = sc.next();
                    count = add(words, count, aWord);
                    break;

                case 2:
                    System.out.println("Display words");
                    System.out.println("We have an array of " + words.length + " integers: " + Arrays.toString(words));
                    break;

                case 3:
                    averageLenth();              
                    break;

                default:
                    System.out.println("Invalid responce");

            }
        } while (choice >= 0 && choice < 4);

    }
}

Answer 1

从显示的代码中，您调用 "averageLength()" 时没有参数，而它需要两个参数：单词数组及其计数。

该调用还包含一个拼写错误（缺少 "g"）。

因此，编译器无法找到该函数，因为它引用了一个实际不存在的函数。

此外，"averageLength()"的两个参数中，单词数组未使用，您重新扫描单词，而不是使用通过开关的其他情况建立的列表。这可能是一个逻辑错误。

Answer 2

请修复：

在方法 main() 中：averageLenth(); 到 averageLength(words, count);
在方法 averageLength() 中：double sum; 到 double sum = 0;

Answer 3

import java.util.Scanner;
import java.util.Arrays;

/**
 * Word Manager
 *
 * @author Harry
 */
public class WrodManager {

    /**
     * Adds the word to the next empty space in the array, if there is space.
     * Returns the new size of the array.
     */
    public static int add(String[] words, int count, String word) {

        if (count < words.length) {
            words[count] = word;
            count++;
        } else {
            System.out.println("The array is full");
        }
        return count;
    }

    /** Displays the words in the collection as a comma separated list. */
    public static void printList(String[] words, int count) {
    }

    public static void averageLength(String[] words, int count) {
        Scanner sc = new Scanner(System.in);
        double average;
        double sum = 0;

        while (sc.hasNext()) {
            String userInput = sc.next();

            double charNum = userInput.length();
            sum = charNum + sum;
            count++;

            if (count > 0) {
                average = sum / count;
                System.out.println("Average word length = " + average);

            }
        }

    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String[] words = new String[20];
        int count = 0;
        String aWord;
        int choice;

        do {
            System.out.println("\t MENU:");
            System.out.println("1. Add a word");
            System.out.println("2. Display words:");
            System.out.println("3. Display average word length");
            System.out.println("4. Quit");
            System.out.println("Enter option: ");
            choice = sc.nextInt();
            System.out.println("choice = " + choice);

            switch (choice) {
            case 1:
                System.out.println("Add a word");
                aWord = sc.next();
                count = add(words, count, aWord);
                break;

            case 2:
                System.out.println("Display words");
                System.out.println("We have an array of " + words.length + " integers: " + Arrays.toString(words));
                break;

            case 3:
                averageLength(words, count);
                break;

            default:
                System.out.println("Invalid responce");

            }
        } while (choice >= 0 && choice < 4);

    }
}

Answer 4

您粘贴的代码存在一些问题 - 其中一些问题已在之前的 comments/answers 中确定，但为了完整起见，我也将在此处列出：

averageLenth 名称中的拼写错误 - 更改为 averageLength。因此，您的代码将无法编译。
averageLength(String[] words, int count) 的签名在调用站点未被接受 - 在交换机内的调用站点更改为 averageLength(words, count)。

averageLength 的实现不正确 - 您的实现实际上并未遍历单词数组并计算平均值，而是似乎在向扫描器询问下一个输入。我已经更改了下面代码中的实现，以通过遍历单词数组来计算平均值。

import java.util.Scanner;
import java.util.Arrays;

/**
 * Word Manager
 *
 * @author Harry
 */
public class WordManager {

/**
 * Adds the word to the next empty space in the array, if there is space.
 * Returns the new size of the array.
 */

public static int add(String[] words, int count, String word) {
    if (count < words.length) {
        words[count] = word;
        count++;
    } else {
        System.out.println("The array is full");
    }
    return count;
}

/**
 * Displays the words in the collection as a comma separated list.
 */
public static void printList(String[] words, int count) {
}


private static void averageLength(String[] words, int count) {
    int sum=0;

    for(int word =0; word < count; word++){
     int wordLength = words[word].length();
     sum += wordLength;
    }

    double averageWorldLength = sum/count;
    System.out.println("Average word length = " +averageWorldLength;
}


public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String[] words = new String[20];
    int count = 0;
    String aWord;
    int choice;

    do {
        displayMenuOptions();
        choice = sc.nextInt();
        System.out.println("choice = " + choice);

        switch (choice) {
            case 1:
                System.out.println("Add a word");
                aWord = sc.next();
                count = add(words, count, aWord);
                break;

            case 2:
                System.out.println("Display words");
                System.out.println("We have an array of " + words.length + " integers: " + Arrays.toString(words));
                break;

            case 3:
                  averageLength(words, count);
                  break;
            default:
                System.out.println("Invalid responce");

        }
    } while (choice >= 0 && choice < 4);
}

private static void displayMenuOptions() {
    System.out.println("\t MENU:");
    System.out.println("1. Add a word");
    System.out.println("2. Display words:");
    System.out.println("3. Display average word length");
    System.out.println("4. Quit");
    System.out.println("Enter option: ");
 }
}

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