JAVA中实现字符返转的方法

package com;

public class Str {
	
	/**
	 * 使用String.toCharArray方法
	 * @param oldString
	 * @return
	 */
	static public String reverString1(String oldString)
	{
		String resultString ="";
		
		char [] charArray = oldString.toCharArray();
		
		for(int i=charArray.length-1 ;i>=0;i--)
		{
			resultString += charArray[i];
		}
		
		return resultString;
	}
	
	
   /**
    * 利用StringBuffer的方法
    * @param oldString
    * @return
    */
	static public String reverString2(String oldString)
	{
		
		
		 StringBuffer strBuffer = new StringBuffer(oldString);
		return strBuffer.reverse().toString();
		
	}
	
	/**
	 * 递归截取实现字符返转
	 * @param oldString
	 * @return
	 */
	public static String reverString3(String oldString)
	{
	  String resultString="";
	   if(oldString.length()==1)
	   {

		   return oldString;
	   }
	   else
	   {
		   String subString1 = oldString.substring(0, oldString.length()-1);    
           String subString2 = oldString.substring(oldString.length()-1);    

             resultString +=subString2;  
          return resultString+ reverString3 (subString1);       
	   }
	}
	
	public static void main(String[] args) {
		
		String oldString = "Hello World!";
     
	    System.out.print(oldString.startsWith("Hello"));
	}

}