code: public static boolean isNumeric(Object obj) {
  		if (obj == null) {
  			return false;
  		}
  		char[] chars = obj.toString().toCharArray();
  		int length = chars.length;
  		if(length < 1)
  			return false;
  		
  		int i = 0;
  		if(length > 1 && chars[0] == '-')
  			i = 1;
  		
  		for (; i < length; i++) {
  			if (!Character.isDigit(chars[i])) {
  				return false;
  			}
  		}
  		return true;
  	}
docs: 检查对象是否为数字型字符串,包含负数开头的。