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java - Java - 单词加扰器[保留第一个和最后一个字母]

问题描述

我的任务是编写一个程序来打乱一个单词，同时保持相同的第一个和最后一个字母并且只交换两个字母，然后提示用户如果他们愿意继续。

示例：userInput = bacon|Output = bcaon

我附上了我的程序的想象，可能有几个问题，但由于图像中的错误，我无法真正运行它。我真的很困惑，因为我有一个助教来帮助我完成这项任务，他们似乎认为这肯定会奏效，但正如你所见，它没有。

如果有人能告诉我到底出了什么问题以及为什么，我将不胜感激。如果您要添加任何内容来使该程序正常运行，我也非常非常感谢您，但最重要的是，我只想了解问题所在以及原因。

import java.util.Scanner;
import java.util.Random;
public class FreeStyle {

public static void main(String[] args) {

    Scanner in = new Scanner(System.in);                        // Importing and initializing keyboard to 'in'
    System.out.println("Please enter a word to be scrambled"); // Asking user for a word
    String word = in.next();                               // Initializing the user's input 
    System.out.println(swapLetters(word));                    

    System.out.println("Would you like to enter another word? y/n");
    String answer = in.next();
    boolean userDone = true; //Using a Boolean statement to ask the user if they are done enter words or not
    while (userDone) {

        if (answer.equals('y')) {
            System.out.println("Please enter a new word");      //Ask user for new word to scramble
            word = in.nextLine();                                   //New initialization for 'word'
        } else if (answer.equals('n')) {                            //If user types 'n', loops then breaks because while(userDone) is false
            userDone = false;
        } else {
            System.out.println("Invalid input, please enter more than 3 letter words."); // The logic doesn't flow or apply to words that are less than 4 letters, so this catches that error and notifies the user
        }
    }
}

private static String swapLetters(String word) { //Private method used for the program only, no need to involve the user

    Random r = new Random(); //Using random instead of math floor
    //int arraysize = word.length();
    int a = r.nextInt(word.length()-2)+1; 
    int b = r.nextInt(word.length()-2)+1;
    //String word2 = word.substring(a, a+1);    
    String word2 = word.substring(0, a) + word.charAt(b)+word.substring(a+1, b)+word.charAt(a)+word.substring(b+1);
    return word2;
}

标签： javaarrayssubstring

解决方案

几点：

  1. 为什么不使用已经完成的东西来完成您正在尝试做的事情 - Collections.shuffle？请参阅代码中的注释以了解其工作原理。
  2. 您不能equals()在 String 和 char 之间使用（' ' 用于字符，" " 用于字符串）。简单的修复 - 只需将您的“y”放入“y”，对于“n”也是如此。
  3. 我在开始时重构了我们用来获取用户输入的代码，然后将其转换为一个单独的方法，因此我们可以再次重用它 - getInputAndScramble。
  4. 最后，我使用了一个 do-while 循环来保持循环，直到用户用“n”字母停止循环。

请在代码中查看我的评论，希望能解决问题。

public class Scrambler {

    public static void main(String[] args) {

        boolean userDone = true; 
        String word;

        Scanner in = new Scanner(System.in);                      
        getInputAndScramble(in); //Extracted method to get Scanner input and scramble

        do {
            System.out.println("Would you like to enter another word? y/n");
            word = in.next();
            while (userDone) {
                if (word.equals("y")) {
                    getInputAndScramble(in);
                    break;
                } else if (word.equals("n")) {                          
                    userDone = false;
                } else {
                    System.out.println("Invalid input, please enter more than 3 letter words."); 
                }
            }
        } while (userDone); //continue until "n"
    }

    private static void getInputAndScramble(Scanner in) {
        System.out.println("Please enter a word to be scrambled"); 
        String word = in.next();                               
        System.out.println(swapLetters(word));
    }

    private static String swapLetters(String word) { 

        /* Convert word into an ArrayList of characters. 
           Create ArrayList size of word, 
           convert String word into a char array and insert every char in                
           the char array into our ArrayList.
        */

        ArrayList<Character> chars = new ArrayList<>(word.length());
        for (char c : word.toCharArray()) {
            chars.add(c);
        }

        //Shuffle, omitting first and last letters
        Collections.shuffle(chars.subList(1, chars.size()-1));

        //Add shuffled letters into an array to output as a word entity
        char[] shuffled = new char[chars.size()];
        for (int i = 0; i < shuffled.length; i++) {
            shuffled[i] = chars.get(i);
        }
        //Return shuffled String
        return new String(shuffled);
    }
}

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