Reversing a String in Java

The following code shows different methods of reversing a String in Java. The simplest being using the reverse() method of StringBuffer, while the other methods use char array and recursion:

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1. public class StringReverse {  
2.     public static void main(String[] args) {  
3.         String s = "zyxwvutsrqponmlkjihgfedcba";  
4.         System.out.println(charReverse(s));  
5.         System.out.println(recursiveReverse(s , new StringBuffer()));  
6.         System.out.println(recursiveReverse2(s, new StringBuffer()));  
7.         System.out.println(bufferReverse(s));  
8.     }  
9.       
10.     public static String charReverse(String s) {  
11.         char[] cArr = s.toCharArray();  
12.         StringBuffer reversed = new StringBuffer();  
13.         for(int i=cArr.length-1; i>=0; i--) reversed.append(cArr[i]);  
14.         return reversed.toString();  
15.     }  
16.       
17.     public static String recursiveReverse(String s, StringBuffer t) {  
18.         if(s.length() > 0) {  
19.             t.append(s.substring(s.length()-1));  
20.             recursiveReverse(s.substring(0, s.length()-1), t);  
21.         }  
22.         return t.toString();  
23.     }  
24.       
25.     public static String recursiveReverse2(String s, StringBuffer sb) {  
26.         if (s.length() == 1){  
27.             sb.append(s);  
28.         }  
29.         else{  
30.             recursiveReverse2(s.substring(1, s.length()), sb);    
31.             sb.append(s.substring(0,1));  
32.         }  
33.         return sb.toString();  
34.     }  
35.       
36.     public static String bufferReverse(String s) {  
37.         StringBuffer sb = new StringBuffer(s);  
38.         return sb.reverse().toString();  
39.     }  
40. }  

public class StringReverse {<br />	public static void main(String[] args) {<br />		String s = "zyxwvutsrqponmlkjihgfedcba";<br />		System.out.println(charReverse(s));<br />		System.out.println(recursiveReverse(s , new StringBuffer()));<br />		System.out.println(recursiveReverse2(s, new StringBuffer()));<br />		System.out.println(bufferReverse(s));<br />	}<br />	<br />	public static String charReverse(String s) {<br />		char[] cArr = s.toCharArray();<br />		StringBuffer reversed = new StringBuffer();<br />		for(int i=cArr.length-1; i>=0; i--) reversed.append(cArr[i]);<br />		return reversed.toString();<br />	}<br />	<br />	public static String recursiveReverse(String s, StringBuffer t) {<br />		if(s.length() > 0) {<br />			t.append(s.substring(s.length()-1));<br />			recursiveReverse(s.substring(0, s.length()-1), t);<br />		}<br />		return t.toString();<br />	}<br />	<br />	public static String recursiveReverse2(String s, StringBuffer sb) {<br />		if (s.length() == 1){<br />			sb.append(s);<br />		}<br />		else{<br />			recursiveReverse2(s.substring(1, s.length()), sb);  <br />			sb.append(s.substring(0,1));<br />		}<br />		return sb.toString();<br />	}<br />	<br />	public static String bufferReverse(String s) {<br />		StringBuffer sb = new StringBuffer(s);<br />		return sb.reverse().toString();<br />	}<br />}