Java常用算法--去除字符串首位空格

public class StringUtils {

    /**
     * trim方法类似java源码
     */
    public String trim(String s){
        char[] c = s.toCharArray();
        int len = c.length;
        int st = 0;
        while(st<len&&c[st]<=' '){
            st++;
        }
        while(st<len&&c[len]<=' '){
            len--;
        }
        return (st>0||len<c.length-1)?subString(s,st,len):s;
    }

    public String subString(String s,int begin,int end){
        return s.substring(begin,end);
    }

    public static void main(String[] args) {
        String s = "  ";
        System.out.println(s.trim().length());
    }

}