扩展 JFrame 与在程序中创建它 [英] Extends JFrame vs. creating it inside the program

问题描述

在使用 Swing 制作应用程序时，我看到人们通过以下两种方式之一来创建 JFrame.哪种方法更好，为什么?

When making an application using Swing, I've seen people do one of the two things to create a JFrame. Which is a better approach and why?

我是 Java 和编程的初学者.我唯一的学习来源是书籍、YouTube 和 StackOverflow.

I'm a beginner at Java and programming. My only source of learning is books, YouTube and Stack Overflow.

import {imports};

public class GuiApp1 {

    public static void main(String[] args) {

        new GuiApp1();
    }

    public GuiApp1()  {
        JFrame guiFrame = new JFrame();

        guiFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        guiFrame.setTitle("Example GUI");
        guiFrame.setSize(300,250);
        ................
    }

和

import {imports};

public class GuiApp1 extends JFrame {

    public Execute() {
        getContentPane().setBackground(Color.WHITE);
        getContentPane().setLayout(null);
        setSize(800, 600);
        .............
    }

    public static void main(String[] args) {
        Execute frame1 = new Execute();
        frame1.setVisible(true);

    }
}

推荐答案

思考:

• 避免扩展 JFrame，因为它会将您的 GUI 与 JFrame 联系起来.相反，如果您专注于创建 JPanel，那么您可以在任何需要的地方自由使用这些 JPanel——在 JFrame、JDialog、JApplet 或另一个 JPanel 内部，或通过 CardLayout 与其他 JPanel 交换.
• 一般避免继承，尤其是复杂的类.这将防止有害错误，例如无意的方法覆盖(尝试创建具有 getX() 和 getY() 方法的 JFrame 或 JPanel 以了解我的意思！).
• 如果您使用的是 IDE，请避免继承复杂的类:如果您覆盖一个复杂的类，那么当您对这些类的对象调用方法时，您将有很多方法可供选择.
• 封装很好，并且允许创建更安全的代码.仅公开需要公开的内容，并尽可能控制该公开.

• Avoid extending JFrame as it ties your GUI to being, well a JFrame. If instead you concentrate on creating JPanels instead, then you have the freedom to use these JPanels anywhere needed -- in a JFrame, or JDialog, or JApplet, or inside of another JPanel, or swapped with other JPanels via a CardLayout.
• Avoid inheritance in general, especially of complex classes. This will prevent pernicious errors, such as inadvertent method overrides (try creating a JFrame or JPanel that has a getX() and getY() method to see what I mean!).
• Avoid inheritance of complex classes if you are using an IDE: If you override a complex class, when you call methods on objects of these classes, you will have many, too many, choices of methods offered to you.
• Encapsulation is good, is and allows for creation of safer code. Expose only that which needs to be exposed, and control that exposure as much as possible.

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