来自其他类的Java重写方法，无需继承 [英] Java override method from another class without inheritance

问题描述

我在这里找到了类似的问题:
无需在Java中进行子类化的替代方法

I found a similar question here:
overriding methods without subclassing in Java

但是我有点不同，我有两个类，一个基于GUI，另一个只是修改第一类元素的方法.如果仅编辑基本函数，我不会遇到任何问题，但是现在我想从第二类重写第一类方法中的jbutton而不继承它.我必须从哪里开始?

But mine a little different, I have two classes, 1 GUI based, and the other just methods to modify elements in first class. If it just editing the basic function, I meet no problem, but now I want to override a jbutton in first class method from the second class without inheriting it. Where do I have to start?

我有一个临时解决方案，那就是第二个类扩展JButton，重写我想要的方法，然后将该类添加到我的GUI类中(不管是否有匿名对象).但是我想找到一种方法来找到解决我的问题的方法，甚至可能吗?谢谢:)

I have temporary solution which is that the second class extends JButton, override method I want to, and add that class to my GUI class (anonymous object or not, is doesn't matter). But I want to discover a way to find a way to my question, is it even possible? Thanks :)

修改
这是示例代码:

Edit
Here's sample code:

第一类，因为它只是jframe中的一个按钮，所以我只在构造函数中添加它们:
ButtonOverrider bo=new ButtonOverrider();->这是替代程序类
button=bo.overridePaintComponent(bo);//第一次尝试
button=bo.overridePaintComponent();//第二次尝试
bo.overridePaintComponent(bo);//第三次尝试

First class, as it only a button in jframe, I only add these in constructor:
ButtonOverrider bo=new ButtonOverrider(); -> this is the overrider class
button=bo.overridePaintComponent(bo); //first try
button=bo.overridePaintComponent(); //second try
bo.overridePaintComponent(bo); //third try

这是ButtonOverrider方法:

And here's the ButtonOverrider method:

public JButton ButtonOverrider(JButton button) {
  button = new JButton() {
    @Override
    protected void paintComponent(Graphics g) {
      Graphics2D g2 = (Graphics2D) g.create();
      GradientPaint gp = new GradientPaint(0, 0,
      Color.blue.brighter().brighter(), 0, getHeight(),
      getBackground().darker().darker());

      g2.setPaint(gp);
      g2.fillRect(0, 0, getWidth(), getHeight());
      g2.dispose();

      super.paintComponent(g);
      super.setContentAreaFilled(false);
      super.setFocusPainted(false);
      super.setBorder(new LineBorder(Color.yellow, 2));
      super.setText("Shuro");
    }
  };
  return button;
}

推荐答案

我必须从哪里开始?

Where do I have to start?

具有继承性.这是覆盖有意义的唯一方法.尚不清楚为什么您不想使用继承，但这确实是覆盖方法的唯一方法.不管使用匿名类还是命名类都没有关系，但是必须扩展类以覆盖该方法.这就是Java中重写工作的方式.

With inheritance. That's the only way that overriding makes any sense. It's not clear why you don't want to use inheritance, but that really is the only way of overriding a method. Whether you use an anonymous class or a named one is irrelevant, but it must extend the class in order to override the method. That's simply the way overriding works in Java.

您在更新的问题中显示的代码通过创建一个匿名内部类来使用继承...但是它并不能满足我的期望，因为它创建一个 new 对象，而不是覆盖现有对象上的方法.您的参数值将永远不会被使用.

The code you've shown in your updated question does use inheritance by creating an anonymous inner class... but it doesn't do what I expect you want it to, because it creates a new object rather than overriding the method on the existing object. Your parameter value is never used.

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