Effective Java 策略枚举

//策略枚举
public enum PayrollDay {

	MONDAY(PayType.WEEKDAY),
	TUESDAY(PayType.WEEKDAY),
	WEDNESDAY(PayType.WEEKDAY),
	THURSDAY(PayType.WEEKDAY),
	FRIDAY(PayType.WEEKDAY),
	SATURDAY(PayType.WEEKEND),
	SUNDAY(PayType.WEEKEND);
	
	private final PayType payType;
	
	PayrollDay(PayType payType){
		this.payType = payType;
	}
	
	double pay(double hoursWorked,double payRate){
		return payType.pay(hoursWorked, payRate);
	}
	//the strategy enum type
	private enum PayType {
		WEEKDAY {
			double overtimePay(double hours,double payRate){
				return hours <= HOURS_PER_SHIFT ? 0 : (hours - HOURS_PER_SHIFT) * payRate / 2;
			}
		},
		WEEKEND{
			double overtimePay(double hours,double payRate){
				return hours * payRate / 2;
			}
		};
		
		private static final int HOURS_PER_SHIFT = 8;
		
		abstract double overtimePay(double hoursWorked,double payRate);
		
		double pay(double hoursWorked,double payRate){
			double basePay = hoursWorked * payRate;
			return basePay + overtimePay(hoursWorked, payRate);
		}
	}
}

测试类

public class PayrollDayTest {

	public static void main(String[] args) {
		System.out.println(PayrollDay.MONDAY.pay(12d, 12d));
		System.out.println(PayrollDay.TUESDAY.pay(12d, 12d));
		System.out.println(PayrollDay.WEDNESDAY.pay(12d, 12d));
		System.out.println(PayrollDay.THURSDAY.pay(12d, 12d));
		System.out.println(PayrollDay.FRIDAY.pay(12d, 12d));
		System.out.println(PayrollDay.SATURDAY.pay(12d, 12d));
		System.out.println(PayrollDay.SUNDAY.pay(12d, 12d));

	}

}