练习——字符反转

package com.someexercise;

import java.util.Arrays;

public class restring {
    /*
    字符反转
    将字符串中指定部分进行反转。比如将"abcdef"反转为"aedcbf"
    编写方法 public static String reverse(String str, int start , int end) 搞定
    再做一些异常处理
     */

    public static void main(String[] args) {

        String aa = "asdqwdffasf";
        System.out.println("===交换前===");
        System.out.println(aa);
        try {
            aa = reverse(aa, 1, 0);
        } catch (Exception e) {
            System.out.println(e.getMessage());
            return;
        } finally {
        }
        System.out.println("===交换后===");
        System.out.println(aa);
    }

    public static String reverse(String str, int start , int end){

        if (!(str!=null && start >= 0 && start <= end && end < str.length())){
            throw new RuntimeException("参数异常");
        }
        System.out.println("===参数正确===");
        char[] aa = str.toCharArray();  //将字符串存入数组
        char temp = '0';
        for (int i = start,j = end;i < j ;i++,j--){
            temp = aa[i];
            aa[i] = aa[j];
            aa[j] = temp;
        }
        return new String(aa);
    }
}