# java 程序：使用`Stack`，`Queue`，`for`或`while`循環檢查回文串 > 原文： [https://beginnersbook.com/2014/01/java-program-to-check-palindrome-string/](https://beginnersbook.com/2014/01/java-program-to-check-palindrome-string/) 在本教程中，我們將看到**程序來檢查給定的`String`是否是回文**。以下是實現目標的方法。 1）使用堆棧 2）使用隊列 3）使用`for`/`while`循環 **程序 1：使用堆棧**進行回文檢查 ```java import java.util.Stack; import java.util.Scanner; class PalindromeTest { public static void main(String[] args) { System.out.print("Enter any string:"); Scanner in=new Scanner(System.in); String inputString = in.nextLine(); Stack stack = new Stack(); for (int i = 0; i < inputString.length(); i++) { stack.push(inputString.charAt(i)); } String reverseString = ""; while (!stack.isEmpty()) { reverseString = reverseString+stack.pop(); } if (inputString.equals(reverseString)) System.out.println("The input String is a palindrome."); else System.out.println("The input String is not a palindrome."); } } ``` 輸出 1： ```java Enter any string:abccba The input String is a palindrome. ``` 輸出 2： ```java Enter any string:abcdef The input String is not a palindrome. ``` **程序 2：回顧檢查使用隊列** ```java import java.util.Queue; import java.util.Scanner; import java.util.LinkedList; class PalindromeTest { public static void main(String[] args) { System.out.print("Enter any string:"); Scanner in=new Scanner(System.in); String inputString = in.nextLine(); Queue queue = new LinkedList(); for (int i = inputString.length()-1; i >=0; i--) { queue.add(inputString.charAt(i)); } String reverseString = ""; while (!queue.isEmpty()) { reverseString = reverseString+queue.remove(); } if (inputString.equals(reverseString)) System.out.println("The input String is a palindrome."); else System.out.println("The input String is not a palindrome."); } } ``` 輸出 1: ```java Enter any string:xyzzyx xyzzyx The input String is a palindrome. ``` 輸出 2: ```java Enter any string:xyz The input String is not a palindrome. ``` **程序 3：使用`for`循環/`While`循環和字符串函數`charAt`** ```java import java.util.Scanner; class PalindromeTest { public static void main(String args[]) { String reverseString=""; Scanner scanner = new Scanner(System.in); System.out.println("Enter a string to check if it is a palindrome:"); String inputString = scanner.nextLine(); int length = inputString.length(); for ( int i = length - 1 ; i >= 0 ; i-- ) reverseString = reverseString + inputString.charAt(i); if (inputString.equals(reverseString)) System.out.println("Input string is a palindrome."); else System.out.println("Input string is not a palindrome."); } } ``` 輸出 1: ```java Enter a string to check if it is a palindrome: aabbaa Input string is a palindrome. ``` 輸出 2: ```java Enter a string to check if it is a palindrome: aaabbb Input string is not a palindrome. ``` 如果你想在上面的程序中使用`While`循環，那么用這段代碼替換`for`循環： ```java int i = length-1; while ( i >= 0){ reverseString = reverseString + inputString.charAt(i); i--; } ```