JTextField無法在Netbeans IDE中按預期方式工作

Question

我有一類叫MainFrem

public class MainFrem extends javax.swing.JFrame {

    public MainFrem() {
        initComponents();

    }

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

        ok = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        ok.setText("ok");
        ok.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                okActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(74, 74, 74)
                .addComponent(ok)
                .addContainerGap(144, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(62, 62, 62)
                .addComponent(ok)
                .addContainerGap(70, Short.MAX_VALUE))
        );

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

    private void okActionPerformed(java.awt.event.ActionEvent evt) {                                   
        new SecondClass().setVisible(true);
        System.out.println("Ok button Pressed.");
        new SecondClass().FeelIn.setText("Operation Successful.");

    }                                  

    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new MainFrem().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton ok;
    // End of variables declaration                   
}

第二類是

public class SecondClass extends javax.swing.JFrame {
    public SecondClass() {
        initComponents();
    }
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        FeelIn = new javax.swing.JTextField();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(48, 48, 48)
                .addComponent(FeelIn, javax.swing.GroupLayout.PREFERRED_SIZE, 67, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(62, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(29, 29, 29)
                .addComponent(FeelIn, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(53, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>                        
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new SecondClass().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    public javax.swing.JTextField FeelIn;
    // End of variables declaration                   
}

我正在使用NetBeans IDE，並且大多數代碼是由IDE生成的。 在名為Mainfrem的類中，我編寫了以下代碼，這是我在兩個類中編寫的唯一代碼。

private void okActionPerformed(java.awt.event.ActionEvent evt) {                                   
    new SecondClass().setVisible(true);
    System.out.println("Ok button Pressed.");
    new SecondClass().FeelIn.setText("Operation Successful.");

}

在名為MainFrem的類中，我使用一個JButton並設置動作偵聽器，如上所示，在名為SecondClass類中，我僅添加了一個名為FeelIn的JTextField。 我試圖按MainFrem類中的ok按鈕，然后將MainFrem的JTextField更改為Operation Successful. SecondClass Operation Successful. 。 SecondClass的JTextField不會更改為Operation Successful SecondClass是否有解決問題的方法。

Answer 1

private void okActionPerformed(java.awt.event.ActionEvent evt) {                                   
    new SecondClass().setVisible(true); // An anonymous SecondClass instance
    System.out.println("Ok button Pressed.");
    new SecondClass().FeelIn.setText("Operation Successful."); // Another anonymous instance?

}

您只是在創建SecondClass的新匿名實例，這就是問題所在。 基本上，您只是在創建實例並將其丟棄。

Answer 2

您new SecondClass()都在調用new SecondClass() 。 我假設您要執行的操作是：

private void okActionPerformed(java.awt.event.ActionEvent evt) {
    SecondClass frame = new SecondClass()                                   
    frame.setVisible(true);
    System.out.println("Ok button Pressed.");
    frame.FeelIn.setText("Operation Successful.");
}