迴文程序沒有給予正確的輸出在Java中

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我在Java中創建一個迴文程序，它通過用戶輸入的字或詞，並將它們放入一個數組。然後它接受反向輸入並將其放入另一個數組中。然後我檢查兩個字是否相同。

我的問題是，程序正在改變其中一個字母，以便它總是正確的，並且它迭代了太多次。任何想法，在我的代碼是什麼造成這個？

public static boolean isPalindrome(char[] a, int used){ 
char[] original = a; 
int newNumber = used - 1; 
for(int i = 0; i <= newNumber; i++){ 
    a[i] = a[newNumber - i ]; 
    System.out.println("Your original word was: " + String.valueOf(original)); 
    System.out.println("Backwards, your word is: " + String.valueOf(a)); 

    } 
if(String.valueOf(original).equalsIgnoreCase(String.valueOf(a))){ 
    System.out.println("Your word or words are palindromes."); 

}else{ 
    System.out.println("Your word or words are not palindromes"); 
} 
return(String.valueOf(original).equalsIgnoreCase(String.valueOf(a))); 
} 

public void userInput(){ 
Scanner keyboard = new Scanner(System.in); 
System.out.println("Enter a word or words that you believe are palindromes: "); 
word = keyboard.next(); 
word = word.replaceAll("\\W",""); 
int length = word.length(); 
char[] p = new char[length]; 
for(int i = 0; i < length; i++){ 
    p[i] = word.charAt(i); 
} 
Palindrome.isPalindrome(p, length); 

}

這是我的輸出，當我輸入 「糖果」。

Your original word was: yandy 
Backwards, your word is: yandy 
Your original word was: ydndy 
Backwards, your word is: ydndy 
Your original word was: ydndy 
Backwards, your word is: ydndy 
Your original word was: ydndy 
Backwards, your word is: ydndy 
Your original word was: ydndy 
Backwards, your word is: ydndy 
Your word or words are palindromes 

感謝大家的回答！ 下面是正確的代碼這樣的作品，雖然效率不高，因爲它可以：

public static boolean isPalindrome(char[] a, int used){ 
    char[] original = a; 
    char[] newArray = new char[used]; 
    int newNumber = used - 1; 
    for(int i = 0; i <= newNumber; i++){ 
     newArray[i] = a[newNumber - i ]; 
     } 
    System.out.println("Your original word was: " + String.valueOf(original)); 
    System.out.println("Backwards, your word is: " + String.valueOf(newArray)); 

    if(String.valueOf(original).equalsIgnoreCase(String.valueOf(newArray))){ 
     System.out.println("Your word or words are palindromes."); 

    }else{ 
     System.out.println("Your word or words are not palindromes"); 
    } 
    return(String.valueOf(original).equalsIgnoreCase(String.valueOf(newArray))); 
    } 

Answer 1

問題是與您的代碼a[i] = a[newNumber - i ];要更改現有陣列。

首先創建新的數組，然後把你的反向字符串。

public static boolean isPalindrome(char[] a, int used) { 
    char[] newA = new char[a.length]; 
    int newNumber = used - 1; 
    for (int i = 0; i <= newNumber; i++) { 
     newA[i] = a[newNumber - i]; 
     System.out.println("Your original word was: " + String.valueOf(a)); 
     System.out.println("Backwards, your word is: " + String.valueOf(newA)); 
    } 
    if (String.valueOf(String.valueOf(newA)).equalsIgnoreCase(String.valueOf(a))) { 
     System.out.println("Your word or words are palindromes."); 

    } else { 
     System.out.println("Your word or words are not palindromes"); 
    } 
    return (String.valueOf(String.valueOf(newA)).equalsIgnoreCase(String.valueOf(a))); 
} 

還有很多其他有效的方法來編寫此代碼。

Answer 2

如果你想在這個簡單的方法來檢查palindrome，你可以嘗試StringBuilder。

public static boolean isPalindrome(String input) { 
    StringBuilder sb=new StringBuilder(input); 
    return input.equals(sb.reverse().toString()); 
} 

在你的情況改變你isPalindrome方法如下

public static void isPalindrome(char[] a, int used){ 
    char[] newArr = new char[a.length]; // create a new array in same length as a 
    int newNumber = used - 1; 
    System.out.println("Your original word was: " + String.valueOf(a)); 
    for(int i = 0; i <= newNumber; i++){ 
     newArr[i] = a[newNumber - i ]; 
    } 
    System.out.println("Backwards, your word is: " + String.valueOf(newArr)); 
    if(String.valueOf(newArr).equalsIgnoreCase(String.valueOf(a))){ 
     System.out.println("Your word or words are palindromes."); 
    }else{ 
     System.out.println("Your word or words are not palindromes"); 
    } 
} 

Answer 3

在您的迴文功能： -

for(int i = 0; i <= newNumber; i++){ 
      a[i] = a[newNumber - i ]; 
      System.out.println("Your original word was: " + String.valueOf(original)); 
      System.out.println("Backwards, your word is: " + String.valueOf(a)); 

      } 

這裏要替換現有的陣列。

你甚至可以嘗試下面的代碼： -

String original, reverse=""; 
       Scanner in = new Scanner(System.in); 

       System.out.println("Enter a string to check if it is a palindrome"); 
       original = in.nextLine(); 

       int length = original.length(); 

       for (int i = length - 1 ; i >= 0 ; i--) 
       reverse = reverse + original.charAt(i); 

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

Answer 4

1. 沒有必要的陣列（只複製referenz）複製，只有創造具有相同的大小和使用的新數組作爲原始數組，使用a。

   char[] reverse = new char[used]; 
   

2. 把system.out，出來的for循環：

   for(int i = 0; i <= newNumber; i++){ 
       reverse[i] = a[newNumber - i ]; 
   } 
   System.out.println("Your original word was: " + String.valueOf(a)); 
   System.out.println("Backwards, your word is: " + String.valueOf(reverse)); 
   

整個isPalindrom功能：

public static boolean isPalindrome(char[] a, int used){ 
    char[] reverse = new char[used]; 
    int newNumber = used -1; 
    for(int i = 0; i <= newNumber; i++){ 
     reverse[i] = a[newNumber - i ]; 
    } 
    System.out.println("Your original word was: " + String.valueOf(a)); 
    System.out.println("Backwards, your word is: " + String.valueOf(reverse)); 

    if(String.valueOf(reverse).equalsIgnoreCase(String.valueOf(a))){ 
     System.out.println("Your word or words are palindromes."); 

    }else{ 
     System.out.println("Your word or words are not palindromes"); 
    } 
    return(String.valueOf(reverse).equalsIgnoreCase(String.valueOf(a))); 
} 

Answer 5

的問題是在你指定的

isPalindrome方法

char[] original = a; 

炭[]變量的引用。通過設置original = a，您正在複製引用，所以現在這兩個數組都指向同一塊內存。

現在，當您修改a時，original也會被修改，因爲它們都指向相同的內存。

您可以通過創建一個新的實例，如下所示解決此問題：

char[] original = new char [a.length]; 
    System.arraycopy(a, 0, original, 0, a.length);