Java - 如何在 switch 语句中调用方法？

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数。 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 来获取平均值时，它不起作用，因为 average 未在 main 下声明code> 方法，位于 averageLength 下。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

您粘贴的代码存在一些问题 - 其中一些问题已在之前的评论/答案中找到，但为了完整起见，我也会在此处列出它们:

1. averageLenth 名称中的拼写错误 - 更改为 averageLength。因此，您的代码将无法编译。
2. 调用站点未遵循 averageLength(String[] Words, int count) 的签名 - 在调用时更改为 averageLength(words, count)位于交换机内部。

3. averageLength 的实现不正确 - 您的实现实际上并不是迭代单词数组并计算平均值，而是似乎要求扫描器提供下一个输入。我更改了下面代码中的实现，以通过迭代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: ");
    }
   }