java string reverse

百度了下。

package interview20170616;

public class Question31
{
	/**
	 * 仅提供测试
	 * 
	 * @author ZengWenFeng
	 * @date 2011.10.09
	 * @param args
	 */
	public static void main(String[] args)
	{
		String str = "qwertyyyyyuuuuusafsaf82739423adsadad888813432";
		
		long startTime01 = System.nanoTime();
		String str01 = reverse01(str);
		System.out.println(str01);
		long endTime01 = System.nanoTime();
		System.out.println(endTime01 - startTime01);//36388
		
		long startTime02 = System.nanoTime();
		String str2 = reverse(str);
		System.out.println(str2);
		long endtime02 = System.nanoTime();
		System.out.println(endtime02 - startTime02);//78375
	}
	
	/**
	 * 倒置字符串
	 * 
	 * @param str 输入字符串    1234
	 * @return 返回倒置的字符串  4321
	 */
	public static String reverse01(String str)
	{
		if ((null == str) || (str.length() <= 1))
		{
			return str;
		}
		
		return new StringBuffer(str).reverse().toString();
	}
	

	/**
	 * 倒置字符串(递归)
	 * 
	 * @param str 输入字符串    1234
	 * @return 返回倒置的字符串  4321
	 */
	public static String reverse(String str)
	{
		if ((null == str) || (str.length() <= 1))
		{
			return str;
		}
		
		return reverse(str.substring(1)) + str.charAt(0);
	}
}