java - 回文法及比较

Question

在我下面的程序中 - 我有 2 个类，PalindromeTester 应该引用 Palindrome 中的 findPalindrome 方法。然而，发生的情况是，传递给 findPalindrome 方法的值始终返回输入的字符串不是回文，即使当我测试诸如 level 或 mom 或 badd 或 madam 之类的字符串时也是如此。

有人可以提出改进建议吗？我很确定我认为我的 findPalindrome 方法没有正确检查字符串。我认为这是方法，但如果有人看到其他任何东西，请随时提出建议。它采用倒数第二个字符并尝试重建它，然后将其与原始字符串进行比较。

import java.util.Scanner;//import scanner class

public class PalindromeTester//class
{
   public static void main(String args[])//main method
   {
      Scanner in = new Scanner(System.in); //scanner object
      String palindrome = new String(); //string to accept user input

      String end = new String("q"); //string to determine user quitting

      for (int a = 0; a >= 0; a++){ //enter loop 
      System.out.println(); 
      System.out.println("Enter a string to check if it is a palindrome"); //ask for initial string 
      System.out.println(); 
      System.out.println("Continue entering strings until you are done. When you are done, enter q to quit."); //remind user to enter q to quit
      palindrome = in.nextLine();//take in string input
      Palindrome original = new Palindrome(palindrome); //palindrome object and passed palindrome to the constructor...but no value yet...so? 
      original = original.findPalindrome(); //call findPalindrome to determine if palindrome is a palindrome

      if (palindrome.equalsIgnoreCase(end)) //if palindrome is q and since end is q and if they are equal, a=-2.  
        a = -2; //when incrementing the max value if ++ will be -1. since -1 is not >= to 0 then for loop exits. 
      System.out.println("Thanks for trying this program"); 

     }  
   }
 }

_____________________________________________________________

    public class Palindrome { 
      String myPalindrome;  
      String myReverse; 

      public Palindrome(){
        myPalindrome = new String(""); 
        myReverse = new String(""); 
      }

      public Palindrome(String palindrome){
        myPalindrome = palindrome; 
      }

      public String findPalindrome (){

          int length = myPalindrome.length();

          for ( int i = length - 1 ; i >= 0 ; i-- )
             myReverse = myReverse + myPalindrome.charAt(i);

          if (myPalindrome.equals(myReverse))
            System.out.println("Entered string is a palindrome.");
          else
            System.out.println("Entered string is not a palindrome.");

          return (""); 
      }


    }

Answer 1

调用字符串构造函数时，您的代码无法初始化 myReverse。因此它被初始化为 null，然后附加回文字符串。你需要修复它。 话虽如此，上面的代码甚至无法编译，并且存在许多基本问题。