jdk1.5新特性5之枚举之模拟枚举类型

模拟方式一

package cn.xy.Enum;

public class TrafficLampEasy
{
private int time;

public final static TrafficLampEasy REDLAMP = new TrafficLampEasy(20);
public final static TrafficLampEasy GREENLAMP = new TrafficLampEasy(20);
public final static TrafficLampEasy YELLOWLAMP = new TrafficLampEasy(5);

public TrafficLampEasy()
{
}

public TrafficLampEasy(int time)
{
this.time = time;
}

public TrafficLampEasy nextLamp()
{
TrafficLampEasy result = new TrafficLampEasy();

if (this == REDLAMP)
{
result = GREENLAMP;
}
else if (this == GREENLAMP)
{
result = YELLOWLAMP;
}
else if (this == YELLOWLAMP)
{
result = REDLAMP;
}
return result;
}

public String getValue()
{
String result = "";

if (this == REDLAMP)
{
result = "红灯,时长:" + time;
}
else if (this == GREENLAMP)
{
result = "绿灯,时长:" + time;
}
else if (this == YELLOWLAMP)
{
result = "黄灯,时长:" + time;
}
return result;
}

public int getTime()
{
return time;
}

public void setTime(int time)
{
this.time = time;
}
}

TrafficLampEasy teRed = TrafficLampEasy.REDLAMP;
System.out.println(teRed.getValue());
System.out.println(teRed.nextLamp().getValue());

从这个例子中我们看出，枚举类型其实就是一个类返回该类本身

模拟方式二

package cn.xy.Enum;

public abstract class TrafficLamp
{
/**
* 下一个灯
*/
public abstract TrafficLamp nextLamp();

/**
* 获取值
*/
public abstract String getValue();

/**
* 时长
*/
private int time;

public TrafficLamp()
{
}

public TrafficLamp(int time)
{
this.time = time;
}

/**
* 红灯，匿名类，相当于继承TrafficLamp抽象类，并实现抽象方法
*/
public final static TrafficLamp REDLAMP = new TrafficLamp(50) {
@Override
public TrafficLamp nextLamp()
{
return GREENLAMP;
}

@Override
public String getValue()
{
return "红灯,时长:" + this.getTime();
}
};

public final static TrafficLamp GREENLAMP = new TrafficLamp(50) {
@Override
public TrafficLamp nextLamp()
{
return YELLOWLAMP;
}

@Override
public String getValue()
{
return "绿灯,时长:" + this.getTime();
}
};

public final static TrafficLamp YELLOWLAMP = new TrafficLamp(2) {
@Override
public TrafficLamp nextLamp()
{
return REDLAMP;
}

@Override
public String getValue()
{
return "黄灯,时长:" + this.getTime();
}
};

public int getTime()
{
return time;
}

public void setTime(int time)
{
this.time = time;
}
}

TrafficLamp red = TrafficLamp.REDLAMP;
System.out.println(red.getValue());
System.out.println(red.nextLamp().getValue());

采用匿名类的方式，那么什么是匿名类呢？

匿名类适合那些只需要使用一次的类

public abstract class AnonymousClassDesk
{
public abstract double getPrice();

public abstract String getName();

}

public class Desk extends AnonymousClassDesk
{
@Override
public double getPrice()
{
return 100;
}

@Override
public String getName()
{
return "普通书桌";
}

}

public static void main(String[] args)
{
AnonymousClassDesk desk = new AnonymousClassDesk() {

@Override
public double getPrice()
{
return 100;
}

@Override
public String getName()
{
return "匿名书桌";
}
};

System.out.println(desk.getName());
}

不仅可以使抽象类，也可以是接口。匿名类没有什么特别的地方，同样还是要实现需要实现的方法。