常量类的实现方式-三种

一、接口常量

public interface Constants{
	/**
	*
	*/
	public static final double PI = 3.1415926;
	//内部类
	public static class VoFilds{
		public static final String name = "China";
	}
}

二、类常量

public class Constants{
	/**
	*
	*/
	public static final double PI = 3.1415926;
	 static {
        // Head 相关
        RESP_INFO.put(PI, "π");
	}
}

三、枚举

publice enum Constants{
	private String day;
	SUN(""),MON(""),TUE(""),WED(""),THU(""),FRI(""),SAT("");
	public Constants(String day){
		this.day = day;
	}
	public String getDay(){
		return this.day;
	}
	public void setDay(String day){
		this.day = day;
	}
}

定义一个常量类+内部枚举类

publice class Constants{
	publice enum Constants{
		private String day;
		SUN(""),MON(""),TUE(""),WED(""),THU(""),FRI(""),SAT("");
		public Constants(String day){
			this.day = day;
		}
		public String getDay(){
			return this.day;
		}
		public void setDay(String day){
			this.day = day;
		}
	}
}

参考文本：JAVA常量类的实现方式_枚举类＿项目实践