java – 调用事件调度线程在哪里？

我读到构造Swing组件和处理事件的所有代码必须由Event dispatch Thread运行.我了解如何通过使用SwingUtilities.invokelater()方法来实现.考虑以下代码,其中GUI初始化在main方法本身完成

public class GridBagLayoutTester extends JPanel implements ActionListener {   
    public GridBagLayoutTester() {
        setLayout(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();

        JButton button = new JButton("Testing");
        gbc.fill = GridBagConstraints.HORIZONTAL;
        gbc.anchor = GridBagConstraints.WEST;
        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.gridwidth = 1;
        button.addActionListener(this);
        add(button,gbc);
    }

    public void actionPerformed(ActionEvent e) {
        System.out.println("event handler code");
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("GridBagLayoutDemo");
        frame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);    
        Container contentPane = frame.getContentPane();
        contentPane.setLayout(new BorderLayout());
        contentPane.add(new GridBagLayoutTester(),BorderLayout.CENTER);
        frame.setSize(800,600);
        frame.pack();
        frame.setVisible(true);
        System.out.println("Exiting");
    }   
}

这段代码如何正常工作？我们正在构建JFrame并在主线程中调用主机的其他方法.我不明白这里EDT在哪里(它执行什么代码？). GridBagLayoutTester类的构造函数也是从main方法调用的,这意味着EDT没有运行它.

简而言之

美国东部时间是什么时候开始？ (如果在运行此代码的同时启动EDT时,JVM是如何启动EDT的)？
>按钮的事件处理程序代码是否在EDT上运行？

void executeOffEDT() {
  if (SwingUtilities.isEventdispatchThread()) {
    Runnable r = new Runnable() {
      @Override
      public void run() {
        OutsideClass.this.executeOffEDTInternal();
      }
    };
    new Thread(r).start();
  } else {
    this.executeOffEDTInternal();
  }
}

void executeOnEDT() {
  if (SwingUtilities.isEventdispatchThread()) {
    this.executeOnEDTInternal();
  } else {
    Runnable r = new Runnable() {
      @Override
      public void run() {
        OutsideClass.this.executeOnEDTInternal();
      }
    };
    SwingUtilities.invokelater(r);
  }
}