判斷字符串是否爲純數字

package com.sun.my;

 

/**
 *
 * @author Administrator
 */

public class PD {
    //判斷輸入的字符串是否爲純數字
    public boolean panduan(String s,int flag){
        int i;
        for(i=0;i<s.length();i++){
            char c;
            c = s.charAt(i);
            if(!(c >= '0' && c <= '9')){
                if((c != '.' && flag == 1) || (c != 'x' && flag == 2) || (flag == 3)){
                    break;
                }
            }
        }
        if(i==s.length()){
            return true;
        } else {
            return false;
        }
    }
}