java - 在Java中，如果类的父/同级对象没有通过扩展关联，我如何引用它们？

Question

我对这个问题真的很困惑，所以请帮助我。网上搜索了一些关于类(class)和父类(class)的描述。但是，我对“父对象”更感兴趣，而不是扩展另一个类(继承)的类。

假设我有以下父类代码:

public class ParentContainer extends JPanel 
{
    public Child1Container myChild1 = new Child1Container();
    public Child2Container myChild2 = new Child2Container();

    public ParentContainer() {
        JLabel lblParent = new JLabel("I'm the parent");
        add(lblParent);

        add(myChild1);
        add(myChild2);

        JLabel lblParentReceiver = new JLabel("Awaiting message from child...");
        add(lblParentReceiver);

        //I'm going to give child 1 a call...
        JButton btnParentToChild1 = new JButton("Parent: Hello Child 1!");
        btnParentToChild1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                JLabel child1Reicever = myChild1.lblChild1Receiver;
                child1Receiver.setText("Parent Says: Hello Child 1?");
            }
        });
        add(btnChild1ToParent);
    }
}

Child1 类的以下代码:

public class Child1Container extends JPanel 
{
    public JLabel lblChild1Receiver = new JLabel("Awaiting message from parent...");

    public Child1Container() {
        JLabel lblChild1 = new JLabel("I'm child 1");
        add(lblChild1);

        //I'm waiting for my parent to give me a call...
        add(lblChild1Receiver);

        //I tried to call my parent, but he can't hear me :(
        JButton btnChild1ToParent = new JButton("Child1: Hello Parent!");
        btnChild1ToParent.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                JLabel parentReceiver = this.getParent().lblParentReceiver;
                parentReceiver.setText("Child1: Hello Parent!");
            }
        });
        add(btnChild1ToParent);

        //I tried to call my sibling, but he can't hear me either :(
        JButton btnChild1ToSibling = new JButton("Child1: Hello Child2!");
        btnChild1ToSibling.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                JLabel child2Receiver = getParent().myChild2.lblChild2Receiver;
                child2Receiver.setText("Child1: Hello Child2!");
            }
        });
        add(btnChild1ToSibling);
    }
}

Child2 类的以下代码:

public class Child2Container extends JPanel 
{
    public JLabel lblChild2Receiver = new JLabel("Awaiting message from sibling...");

    public Child2Container() {
        JLabel lblChild2 = new JLabel("I'm child 2");
        add(lblChild2);

        //I'm waiting for my sibling to give me a call... I feel so alone :(
        add(lblChild2Receiver);
    }
}

如您所见，这是一个孤独的数字世界。在一系列 JPanel 容器中，除了父级与子级之外，没有人能够相互通信。有办法解决这个问题吗？

Answer 1

如果您希望子(包含)对象能够与父(容器)通信，您可以将父对象的引用传递给子对象的构造函数:

public Child1Container(JPanel parent) {
    ...
    this.parent = parent;
    ...
}

然后子级可以调用父级的任何公共(public)方法。

您可以在 ParentContainer 类中拥有一个方法:

public void callSiblings (JPanel from, String message)
{
    // sends message to all the children except of the sender child
}

然后 child 可以调用该方法并向其 sibling 发送消息:

this.parent.callSiblings (this, "hello brother!");