泛型创建类型数组

方法一：创建一个显式的工厂对象，获得编译检查。

package com.cognizant.ch15;

interface FactoryI<T>{
T create();
}
class Foo2<T>{
private T x;
public <F extends FactoryI<T>> Foo2(F factory){
x=factory.create();
}
}
class IntegerFactory implements FactoryI<Integer>{
public Integer create(){
return new Integer(10);
}
}
class Widget {

public static class Factory implements FactoryI<Widget>{
public Widget create(){
return new Widget();
}
}
}
public class FactoryConstraint {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
new Foo2<Integer>(new IntegerFactory());
new Foo2<Widget>(new Widget.Factory());
}

}

方法二：模版方法设计模式

package com.cognizant.ch15;

abstract class GenericWithCreate<T> {
final T element;

GenericWithCreate() {
element = create();
}

abstract T create();
}

class X {
}

class Creator extends GenericWithCreate<X> {
X create() {
return new X();
}

void f() {
System.out.println(element.getClass().getSimpleName());
}
}

public class CreatorGenetic {
public static void main(String[] args){
Creator c= new Creator();
c.f();
}
}
output：X