我可以在静态上下文中以某种方式使用非静态变量吗？

Question

我是Java的新手，我的代码有些麻烦。

是否可以在我的静态类Displaying中使用 JTextArea类的非静态方法displayText.setText ？

非常感谢您的任何帮助！

这是我的代码：

public class GUI extends javax.swing.JFrame {
    Thread send, receive, abc;
    public String x;
    private String response, nonStaticString;

    public GUI() {
        initComponents();
        abc = new Thread(new Displaying());
        abc.start();
        receive = new Thread(new Receiving(this));
        receive.start();
    }

    private static class Displaying implements Runnable {

        private final ArrayList<String> myArray = new ArrayList();
        static BlockingQueue<String> queue = new LinkedBlockingQueue();
        String s;

        @Override
        public void run() {
            while (true) {
                try {
                    s = queue.take();
                    myArray.add(s);
                    for (String myArray1 : myArray) {
                        //System.out.println(myArray1);

                        displayText.setText(myArray);

                    }

                } catch (InterruptedException ex) {
                    Logger.getLogger(GUI.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
        }
    }

    public void setStringToShow(String stringToShow) throws InterruptedException {
        this.response = stringToShow;
        //displayText.setText(response);
        Displaying.queue.put(stringToShow);
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        sendButton = new javax.swing.JButton();
        getTheText = new javax.swing.JTextField();
        jLabel1 = new javax.swing.JLabel();
        jScrollPane2 = new javax.swing.JScrollPane();
        displayText = new javax.swing.JTextArea();
        jLabel2 = new javax.swing.JLabel();
        exitButtom = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        sendButton.setText("Send The Message!");
        sendButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                sendButtonActionPerformed(evt);
            }
        });

        getTheText.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                getTheTextActionPerformed(evt);
            }
        });

        jLabel1.setText("Witam w komunikatorze kliencie 2");

        displayText.setEditable(false);
        displayText.setColumns(20);
        displayText.setRows(5);
        jScrollPane2.setViewportView(displayText);
        displayText.getAccessibleContext().setAccessibleParent(this);

        jLabel2.setText("Write something to your Friend");

        exitButtom.setText("Wyjscie");
        exitButtom.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                exitButtomActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                        .addGap(0, 182, Short.MAX_VALUE)
                        .addComponent(jLabel1)
                        .addGap(85, 85, 85)
                        .addComponent(exitButtom))
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(getTheText)
                            .addComponent(jScrollPane2)
                            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                                .addGap(0, 0, Short.MAX_VALUE)
                                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                    .addComponent(sendButton, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, 215, javax.swing.GroupLayout.PREFERRED_SIZE)
                                    .addComponent(jLabel2, javax.swing.GroupLayout.Alignment.TRAILING))))
                        .addContainerGap())))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(exitButtom)
                    .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(47, 47, 47)
                .addComponent(jLabel2)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(jScrollPane2, javax.swing.GroupLayout.DEFAULT_SIZE, 176, Short.MAX_VALUE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(getTheText, javax.swing.GroupLayout.PREFERRED_SIZE, 38, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(sendButton)
                .addContainerGap())
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );

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

    private void sendButtonActionPerformed(java.awt.event.ActionEvent evt) {                                           
        x = getTheText.getText();
        System.out.println("String: " + x);
        send = new Thread(new Sending(x));
        send.start();
        getTheText.setText("");

    }                                          

    private void getTheTextActionPerformed(java.awt.event.ActionEvent evt) {                                           
        getTheText.getText();
    }                                          

    private void exitButtomActionPerformed(java.awt.event.ActionEvent evt) {                                           
        System.exit(0);
    }                                          


    // Variables declaration - do not modify                     
    public javax.swing.JTextArea displayText;
    private javax.swing.JButton exitButtom;
    public javax.swing.JTextField getTheText;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JScrollPane jScrollPane2;
    public javax.swing.JButton sendButton;
    // End of variables declaration                   

Answer 1

使displayText成为GUI类的成员，并将其传递给Displaying类的构造函数。

但是还有另一个问题。 您不得从非Swing线程调用SWING代码。 查看有关如何解决此问题的SwingUtilities.invokeLater（） 。

Answer 2

不，你不能。 该代码将无法编译。 静态方法“属于”该类，而非静态变量则属于该类的每个实例。 当您处于类的上下文中时，您仍然不知道变量值是什么，并且在某些实例中可能有所不同。

Answer 3

不，非静态变量/方法不能在静态引用中使用。 因此，非静态变量取决于对象的状态，而静态引用则不然。