Question

我有两个名为 GUIFrame 的类，它包含所有图形元素和一个名为 squeak 的线程类。在 GUIFrame 中有两个图形元素，第一个按钮在点击时启动线程：

futures.put(1, pool.submit(new squeak("SqueakyThread",this.jTextArea1)));

第二个是 javax.swing.JTextArea ，其变量名为 jTextArea1 。

提到的第二个类是名为 squeak（实现Runnable）的线程类，并包含 while（true）循环。所有这一类都会产生1到10之间的随机数，然后将该数字输出到 GUIFrame 类中的 jTextArea1 。

问题：这是用Java更新GUI元素的正确方式吗？

我意识到这个问题已经被问了很多，但是我有很多不同的答案，我希望这可以为我和其他人提供一个简单的模板。

GUIFrame.java

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;


public class GUIFrame extends javax.swing.JFrame {

    public GUIFrame() {
        this.pool = Executors.newCachedThreadPool();
        initComponents();
    }

    private ExecutorService pool;
    private Map<Integer, Future<?>> futures = new HashMap<>();
    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jButton1 = new javax.swing.JButton();
        jScrollPane2 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jButton1.setText("Start");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jTextArea1.setEditable(false);
        jTextArea1.setColumns(20);
        jTextArea1.setRows(5);
        jScrollPane2.setViewportView(jTextArea1);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 468, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(18, 18, 18)
                .addComponent(jButton1, javax.swing.GroupLayout.DEFAULT_SIZE, 188, Short.MAX_VALUE)
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                        .addGap(0, 0, Short.MAX_VALUE)
                        .addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 96, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addComponent(jScrollPane2, javax.swing.GroupLayout.DEFAULT_SIZE, 444, Short.MAX_VALUE))
                .addContainerGap())
        );

        pack();
    }// </editor-fold>                        

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
        futures.put(1, pool.submit(new squeak("SqueakyThread",this.jTextArea1)));
    }                                        

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(GUIFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(GUIFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(GUIFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(GUIFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                new GUIFrame().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JScrollPane jScrollPane2;
    private javax.swing.JTextArea jTextArea1;
    // End of variables declaration                   
}

squeak.java

import java.util.Random;
import java.util.concurrent.TimeUnit;
import javax.swing.SwingUtilities;

public class squeak implements Runnable {

    private  String Type = "";
    private  javax.swing.JTextArea MW;

    squeak (String type, javax.swing.JTextArea MW)
    {
        this.Type = type;
        this.MW = MW;
    }

    @Override
    public void run ()
    {

        while(true)
        {
            UpdateGUI(RandomNumber()+"\r\n");

            try {
                TimeUnit.SECONDS.sleep(10);
            } catch (InterruptedException e)
            {
                UpdateGUI("Thread is now Exiting!\r\n");
                //Return cause program to exit the while(true) loop and end
                return;
            }
        }
    }

    private int RandomNumber(){
        Random r = new Random();
        int num = r.nextInt(10-1) + 1;
        return num;
    }


    private void UpdateGUI(final String foo) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                // Here, we can safely update the GUI
                // because we'll be called from the
                // event dispatch thread
                MW.append(foo);
            }
        });
    }
}

Answer 1

关于，

private void updateGUI(final String foo) {
    SwingUtilities.invokeLater(new Runnable() {
        @Override
        public void run() {
            // Here, we can safely update the GUI
            // because we'll be called from the
            // event dispatch thread
            MW.append(foo);
        }
    });
}

是的，这绝对是允许非Swing事件线程中的代码更新Swing组件的一种方法 - 通过SwingUtilities.invokeLater(new Runnable() {...})将Runnable排队到Swing事件线程队列。

另一种方式，也是我的首选方式，是使用SwingWorker，因为它内置了机器，允许在后台线程中运行代码，并且仍然能够在Swing事件线程上安全地进行Swing调用。

我的第一个批评（我必须找到批评的东西，对吗？）是你的代码应遵循Swing命名约定。例如，变量名称应以小写字母开头，而不是大写字母。如果您只是为自己的乐趣创建代码，那么这一点并不那么重要，但如果您希望其他人审核或更新或维护您的代码，这一点就变得非常重要。

我的第二个批评是：

    jButton1.addMouseListener(new java.awt.event.MouseAdapter() {
        public void mouseReleased(java.awt.event.MouseEvent evt) {
            jButton1MouseReleased(evt);
        }
    });

你不应该将MouseListeners用于JButton，因为它的级别太低了。使用ActionListeners，因为它是它们的用途，并且更安全。例如，如果您的代码禁用了按钮的Action或其模型，则该按钮不应响应，但您的代码将无法正常运行且无法正确禁用。

Java GUI线程和更新

1 个答案: