java基础-字符串反转

java基础-字符串反转
思想：
1，将字符串变成数组
2、将数组反转
3、将数组变成字符串

import java.lang.String;
public class StringInverse
{
    public static void main(String[] args)
    {
        String s="  ab cd  ";
        sop("("+s+")");
        sop("("+reverseString(s)+")");
        sop("("+reverseString(s,3,7)+")");
    }
    private static void sop(String s)
    {
        System.out.println(s);
    }
    private static String reverseString(String s)
    {
        return reverseString(s,0,s.length());
    }

    private static String reverseString(String s,int start,int end)
    {
        //将字符串变成数组
        char[]arr=s.toCharArray();
        //将数组反转
        reverse(arr,start,end);
        //将数组变成字符串
        return new String(arr);
    }
    private static void reverse(char[]arr,int x,int y)
    {
        for(int start=x,end=y-1;start<end;start++,end--)
        {
            swap(arr,start,end);
        }
    }
    private static void swap(char[]arr,int x,int y)
    {
        char temp=arr[x];
        arr[x]=arr[y];
        arr[y]=temp;
    }
}