Java中如何访问一个对象的父对象？

看看这个例子：

class Parent{
    Child child = new Child();
    Random r = new Random();
}

class Child{

    public Child(){
        //access a method from Random r from here without creating a new Random()
    }
}

如何从 Child 对象中访问 Random 对象？

有Parent类传递它自己的实例Random to the Child class.

class Parent{
    Child child;
    Random r = new Random();

    public Parent()
    {
        child = new Child(r);
    }
}

class Child{    
    public Child(Random r){

    }    
}

经典的奥卡姆剃刀。