java - 如何使用 Jbutton 执行具有 main 方法的类

Question

我想通过单击 Jbutton 从另一个也具有 main 方法的类中调用并执行一个具有 main 方法的类。Example1 的类具有完全独立运行的 main 方法:

import org.nlogo.app.App;
public class Example1 {
  public static void main(String[] argv) {
    App.main(argv);
    try {
      java.awt.EventQueue.invokeAndWait(
    new Runnable() {
      public void run() {
        try {
          App.app().open("C:/Users/fmar825/Desktop/fire.nlogo");
        }
        catch(java.io.IOException ex) {
          ex.printStackTrace();
        }}});
    }
    catch(Exception ex) {
      ex.printStackTrace();
    }
  }
}

但是当我从另一个类调用它并通过单击 Jbutton 来执行时。

  private void okbtnActionPerformed(java.awt.event.ActionEvent evt) {                                      
    
        Example1 object=new Example1();
        try {
               object.main(new String[0] );
            } catch (Exception e) {
                e.printStackTrace();
            }
    
    } 

我收到以下错误消息。

ava.lang.Error: Cannot call invokeAndWait from the event dispatcher thread
	at java.awt.EventQueue.invokeAndWait(EventQueue.java:1289)
	at java.awt.EventQueue.invokeAndWait(EventQueue.java:1282)
	at org.nlogo.awt.EventQueue$.invokeAndWait(EventQueue.scala:19)
	at org.nlogo.app.App$.main(App.scala:150)
	at org.nlogo.app.App.main(App.scala)
	at Example1.main(Example1.java:4)
	at User.okbtnActionPerformed(User.java:995)
	at User.access$1600(User.java:31)
	at User$19.actionPerformed(User.java:604)
	at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
	at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346)
	at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
	at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
	at java.awt.Component.processMouseEvent(Component.java:6525)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
	at java.awt.Component.processEvent(Component.java:6290)
	at java.awt.Container.processEvent(Container.java:2234)
	at java.awt.Component.dispatchEventImpl(Component.java:4881)
	at java.awt.Container.dispatchEventImpl(Container.java:2292)
	at java.awt.Component.dispatchEvent(Component.java:4703)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
	at java.awt.Container.dispatchEventImpl(Container.java:2278)
	at java.awt.Window.dispatchEventImpl(Window.java:2739)
	at java.awt.Component.dispatchEvent(Component.java:4703)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746)
	at java.awt.EventQueue.access$400(EventQueue.java:97)
	at java.awt.EventQueue$3.run(EventQueue.java:697)
	at java.awt.EventQueue$3.run(EventQueue.java:691)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
	at java.awt.EventQueue$4.run(EventQueue.java:719)
	at java.awt.EventQueue$4.run(EventQueue.java:717)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:716)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
java.lang.NullPointerException
	at org.nlogo.window.RuntimeErrorDialog.suppressJavaExceptionDialogs(RuntimeErrorDialog.java:63)
	at org.nlogo.app.App.handle(App.scala:779)
	at org.nlogo.util.Exceptions$.handle(Exceptions.scala:21)
	at org.nlogo.app.App$$anon$7.uncaughtException(App.scala:305)
	at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:1057)
	at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:1052)
	at java.awt.EventDispatchThread.processException(EventDispatchThread.java:223)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:215)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

Answer 1

将 invokeAndWait 更改为 invokeLater

本质上，您的 JButton 正在事件调度线程的上下文中执行 ActionListener，这就是它的工作原理。当您调用 Example1.main 时，它会尝试在事件调度线程的上下文中调用 Runnable，但会阻止当前线程(即 EDT)直到其完成。这显然是无法实现的，为了防止可能的线程死锁，invokeAndWait 将抛出异常。

您“还可以”将Example1中的代码更改为...

Runnable runnable = new Runnable() {
    public void run() {
        try {
            App.app().open("C:/Users/fmar825/Desktop/fire.nlogo");
        } catch(java.io.IOException ex) {
            ex.printStackTrace();
        }
    }
};

if (EventQueue.isDispatchThread()) {
    runnable.run();
} else {
    try {
        java.awt.EventQueue.invokeAndWait(runnable);
    } catch(Exception ex) {
        ex.printStackTrace();
    }    
}

它检查当前线程是否是 EDT，如果是，则直接调用 Runnable 的 run 方法，否则调用 invokeAndWait。这将更好地模仿从 EDT 上下文中调用时的原始行为

可运行示例

对我来说效果很好...

父(GUI)类...

import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Parent {

    public static void main(String[] args) {
        new Parent();
    }

    public Parent() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            setLayout(new GridBagLayout());
            JButton makeItSo = new JButton("Make it so");
            makeItSo.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    Child.main(new String[0]);
                }
            });
            add(makeItSo);
        }

    }

}

子(其他主)类

import java.awt.EventQueue;
import javax.swing.JOptionPane;

public class Child {

    public static void main(String[] args) {
        Runnable runnable = new Runnable() {
            public void run() {
                JOptionPane.showMessageDialog(null, "I'm a banana");
            }
        };

        if (EventQueue.isDispatchThread()) {
            System.out.println("Execute within the EDT");
            runnable.run();
        } else {
            try {
                System.out.println("Invoke and Wait");
                java.awt.EventQueue.invokeAndWait(runnable);
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }

    }
}