Java:组件如何了解其所有者 [英] Java: how does a component know its owner

问题描述

假设我有一个类 A 和一个类 B .

Suppose I have a class A and a class B.

public class A {

    private B b;

    public A() {
        this.b = new B();
    }

    public B getB() {
        return this.b;
    }
}

public class B {

    public String getSome() {
        return "Get some!";
    }
}

我知道我可以通过A获得B，因为A 拥有(或拥有拥有)B: new A().getB().
但是如果我有B，我能得到A吗?

I know I can get B through A, because A has (or owns) B: new A().getB().
But if I have B, can I get A?

推荐答案

当然，只需在类B中添加例程 getA()，然后将构造函数中的行更改为

Sure, just add routine getA() in you class B, and change the line in your constructor to

public A() {
    this.b = new B(this);
}

这当然假定您的B类具有一个接受 A (例如

This of course assumes your class B has a constructor which accepts an A, e.g.,

public B(A a) {
    this.a = a;
}

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