Sophomore Java Homework-P5.15 v2

/**
 * Name: Method practice - String reverse (recursive method)
 * @author LinChuWen
 * Date: 2014.10.22
 *
 * NCHU EE,course number:2335
 * course name: Object Oriented Language
 * Textbook: Big Java:Late Objects-Cay S. Horstmann
 * Problem: P5.15
 * Description: Input a string, reverse it, print out the result.
 */
import java.util.*;
public class HW4_P5_15_v2 {

    private static int counter=0;

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Please input a string: ");

        while(input.hasNext()){
            String str_input = input.nextLine();
            System.out.printf("reverse result: %s\n\n", reverse(str_input));
            System.out.print("Please input a string: ");
            counter=0;
        } //while end

        input.close();
    } //main end

    public static String reverse( String str ){
        counter++;

        if(counter<str.length()-counter+1){
            str = str + str.charAt(str.length()-2*counter);
            return reverse(str);
        } //if end
        else
            return str.substring(counter-1, str.length());

    } //reverse() end

} //class end