factoryconstraint.java

来自「java编程思想(第四版)书中原代码 ,对初学者很有用的东西」· Java 代码 · 共 35 行

//: generics/FactoryConstraint.java

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(0);
  }
}	

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

public class FactoryConstraint {
  public static void main(String[] args) {
    new Foo2<Integer>(new IntegerFactory());
    new Foo2<Widget>(new Widget.Factory());
  }
} ///:~