Contents

1. 1. Generator.java:
2. 2. 实例1：
   1. 2.1. Coffee.java:
   2. 2.2. Latte.java:
   3. 2.3. Mocha.java:
   4. 2.4. CoffeeGenerator.java:
3. 3. 实例2：

泛型应用 Generator生成器 用于创建对象

Generator.java:

package lianxi;

public interface Generator<T> {
	T RandomNext();
}

实例1：

Coffee.java:

package lianxi;

public class Coffee {
	private static long counter = 0;
	private final long id = counter++;
	public String toString()	{
	
		return getClass().getSimpleName() + " " + id;
	}
}

Latte.java:

package lianxi;

public class Latte extends Coffee{
	
}

Mocha.java:

package lianxi;

public class Mocha extends Coffee{

}

CoffeeGenerator.java:

package lianxi;

import java.util.Iterator;
import java.util.Random;

public class CoffeeGenerator implements Generator<Coffee>, Iterable<Coffee>{
	
	private Class[] types = {Latte.class, Mocha.class};//咖啡的种类
	private static Random rand = new Random(47);
	public CoffeeGenerator() {}
	
	//For iteration:			//实现了Iterable接口，所以可以在循环语句中使用它，不过需要一个末尾哨兵，所以实现了第2个构造器
	private int size = 0;
	public CoffeeGenerator(int size)	{
	
		this.size = size;
	}
	public Coffee RandomNext()	{
	
		try{//返回一个随机咖啡种类的实例
			return (Coffee) types[rand.nextInt(types.length)].newInstance();
		}catch(Exception e){
			throw new RuntimeException(e);
		}
	}
	
	class CoffeeIterator implements Iterator<Coffee>{
		int count = size;
		public boolean hasNext(){ return count > 0;}
		public Coffee next(){
			count--;
			return CoffeeGenerator.this.RandomNext();
		}
		public void remove(){
			throw new UnsupportedOperationException();
		}
	};
	
	@Override
	public Iterator<Coffee> iterator(){
		return new CoffeeIterator();
	}
	
	public static void main(String[] arges){
		CoffeeGenerator gen = new CoffeeGenerator();
		for(int i = 0; i < 5; i++)
			System.out.println(gen.RandomNext());
		System.out.println("----------------");
		for(Coffee c : new CoffeeGenerator(5))
			System.out.println(c);
	}
}
输出：
Mocha 0
Latte 1
Mocha 2
Latte 3
Latte 4
----------------
Mocha 5
Latte 6
Latte 7
Mocha 8
Mocha 9

实例2：

package lianxi;

public class Fibonacci implements Generator<Integer>{
	
	private int count = 0;
	
	public Fibonacci() {}
	
	public Integer RandomNext()	{
	
		return fib(count++);
	}
	
	public int fib(int n)	{
	
		if(n < 2)	return 1;
		return fib(n - 1) + fib(n - 2);
	}
	
	public static void main(String[] args)	{
	
		Fibonacci gen = new Fibonacci();
		for(int i = 0; i < 18; i++)
			System.out.print(gen.RandomNext() + " ");
	}
	
}
输出：
1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584