使用final和static来修饰的变量称为常量,常量用大写字母表示,字母间用下划线连接。
Java中定义常量有以下几种方式:
interface ConstantInterface { String SUNDAY = "SUNDAY"; String MONDAY = "MONDAY"; String TUESDAY = "TUESDAY"; String WEDNESDAY = "WEDNESDAY"; String THURSDAY = "THURSDAY"; String FRIDAY = "FRIDAY"; String SATURDAY = "SATURDAY"; }
enum ConstantEnum { SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY }
class ConstantClassField { public static final String SUNDAY = "SUNDAY"; public static final String MONDAY = "MONDAY"; public static final String TUESDAY = "TUESDAY"; public static final String WEDNESDAY = "WEDNESDAY"; public static final String THURSDAY = "THURSDAY"; public static final String FRIDAY = "FRIDAY"; public static final String SATURDAY = "SATURDAY"; }
第一种方式利用了接口(Interface)的中变量默认为static final的特性,但是不符合接口设计的初衷。
第三种方式如果静态变量很多时,如果我们只需要其中的一个常量,导致的结果却是整个类被加载到内存中,这点是需要注意的,特别是类中的常量很多时。
原文:http://www.cnblogs.com/lnlvinso/p/4364329.html