多例模式 枚舉 內部類

1.多例模式

私有化構造函數實現, 只能獲得有限個靜態對象.

2.枚舉

多例模式的自動生成版, 語法上一樣, 類類型

3.內部類

類定義爲  abstract, 實例化時, 構造函數後 用一對 { } 實現好 類的 abstract 方法

public abstract class Male {

	public static Male BOY = new Male() {

		public boolean isMemory() {

			return false;
		}
	};

	public static Male MAN = new Male() {

		public boolean isMemory() {

			return true;
		}
	};

	private Male() {
		System.out.println("Male Construct");
	}

	public abstract boolean isMemory();
}

public enum MaleEnum {
	BOY {
		public boolean isMemory() {
			return false;
		}
	},
	MAN {
		public boolean isMemory() {
			return true;
		}
	};
	
	// public MaleEnum() { 要自己聲明的話必須要私有
	//
	// }

	private MaleEnum() {

		System.out.println("MaleEnum CONSTRUCT");
	}

	public abstract boolean isMemory();
}

public class testEnum {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		System.out.println(Male.BOY.isMemory());
		System.out.println(Male.MAN.isMemory());

		System.out.println(MaleEnum.BOY.isMemory());
		System.out.println(MaleEnum.MAN.isMemory());
	}
}

Male Construct
Male Construct
false
true
MaleEnum CONSTRUCT
MaleEnum CONSTRUCT
false
true