仿照trim()方法，寫出去除首尾的特殊字符

例如**ab*.c* === ab*.c

package com.auth.test;
/**
 * @author kang
 * @version 1.0
 * @date 2019/12/11 10:07
 */
public class demo2 {
    public static void main(String[] args) {
        getString("**ab*.c*");
        String specificString = getSpecificString("**ab*.c*");
        System.out.println("真的笨:"+ specificString);
    }
    
    /**
        方法一
        */
    private static String getSpecificString(String s) {
        //字符串長度
        int len = s.length();
        //開始角標
        int st = 0;
        //將字符串轉爲char數組
        char[] val = s.toCharArray();
        while((st < len) && (val[st] <= '*')){
            st++;
        }
        while((st < len) && (val[len-1] <= '*')){
            len--;
        }
        return ((st > 0) || (len < s.length())) ? s.substring(st, len) : s;
    }

    /**
        方法二
        */
    public static String getString(String str){
        str = "**ab*.c*";
        boolean b = str.endsWith("*");
        boolean c = str.startsWith("*");
        while(b==true){
            str = str.substring(0,str.length()-1);
            b = str.endsWith("*");
        }
        while(c==true){
            str = str.substring(1);
            c = str.startsWith("*");
        }
        System.out.println(b);
        System.out.println(c);
        System.out.println(str);
        return str;
    }


}

false
false
ab*.c
真的笨:ab*.c