java - 我在面板上有一个用于按钮的 actionListener，获取空指针

Question

我已经查看并测试了各种方法，但是这个面板(通过另一个面板组件调用)将看不到 actionListener 已设置。我正在 Netbeans 7.0 中工作。这是面板代码:

public class PanelAddClient extends javax.swing.JPanel {

 private AppEventListener appEventListener;



public PanelAddClient() {
    initComponents();
    //paneClientDBTable = new PanelClientDBTable(sqlModule);


}

/**
 * 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() {
    java.awt.GridBagConstraints gridBagConstraints;

    jToolBar1 = new javax.swing.JToolBar();
    filler1 = new javax.swing.Box.Filler(new java.awt.Dimension(500, 0), new java.awt.Dimension(500, 0), new java.awt.Dimension(500, 32767));
    jLabel11 = new javax.swing.JLabel();
    jPanel1 = new javax.swing.JPanel();
    jLabel1 = new javax.swing.JLabel();
    textClientNo = new javax.swing.JTextField();
    jLabel2 = new javax.swing.JLabel();
    textFName = new javax.swing.JTextField();
    jLabel3 = new javax.swing.JLabel();
    textLName = new javax.swing.JTextField();
    jLabel4 = new javax.swing.JLabel();
    textStreetAddress = new javax.swing.JTextField();
    jLabel5 = new javax.swing.JLabel();
    textCity = new javax.swing.JTextField();
    jLabel6 = new javax.swing.JLabel();
    comboStatebox = new javax.swing.JComboBox();
    jLabel7 = new javax.swing.JLabel();
    textZipCode = new javax.swing.JTextField();
    jPanel2 = new javax.swing.JPanel();
    jLabel8 = new javax.swing.JLabel();
    textHomePhone = new javax.swing.JTextField();
    jLabel9 = new javax.swing.JLabel();
    textMobilePhone = new javax.swing.JTextField();
    jLabel10 = new javax.swing.JLabel();
    textEmail = new javax.swing.JTextField();
    buttonAddClient = new javax.swing.JButton();

    setLayout(new java.awt.BorderLayout());

    jToolBar1.setBackground(new java.awt.Color(102, 0, 102));
    jToolBar1.setFloatable(false);
    jToolBar1.setRollover(true);
    jToolBar1.add(filler1);

    jLabel11.setFont(new java.awt.Font("Tahoma", 1, 18)); // NOI18N
    jLabel11.setForeground(new java.awt.Color(51, 255, 51));
    jLabel11.setText("Add New Client Panel");
    jToolBar1.add(jLabel11);

    add(jToolBar1, java.awt.BorderLayout.PAGE_START);

    jPanel1.setBackground(new java.awt.Color(204, 0, 204));

    jLabel1.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
    jLabel1.setForeground(new java.awt.Color(255, 255, 255));
    jLabel1.setText("Client Number:");

    textClientNo.setToolTipText("");
    textClientNo.setPreferredSize(new java.awt.Dimension(50, 15));

    jLabel2.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
    jLabel2.setForeground(new java.awt.Color(255, 255, 255));
    jLabel2.setText("First Name :");
    jLabel2.setToolTipText("");

    textFName.setToolTipText("");

    jLabel3.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
    jLabel3.setForeground(new java.awt.Color(255, 255, 255));
    jLabel3.setText("Last Name :");
    jLabel3.setToolTipText("");

    textLName.setToolTipText("");

    jLabel4.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
    jLabel4.setForeground(new java.awt.Color(255, 255, 255));
    jLabel4.setText("Stree Address :");

    textStreetAddress.setToolTipText("");

    jLabel5.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
    jLabel5.setForeground(new java.awt.Color(255, 255, 255));
    jLabel5.setText("City :");

    textCity.setToolTipText("");

    jLabel6.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
    jLabel6.setForeground(new java.awt.Color(255, 255, 255));
    jLabel6.setText("State :");

    comboStatebox.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "AL", "AK", "MS", "CA", "TX", "OK", "GA", "SC", "TN", "NC", "NY", "IL", "LA", "IN", "WA", "ND", "SD", "MD", "CO", "MA", "RI" }));

    jLabel7.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
    jLabel7.setForeground(new java.awt.Color(255, 255, 255));
    jLabel7.setText("Zip Code :");

    textZipCode.setToolTipText("");

    jPanel2.setBackground(new java.awt.Color(204, 0, 204));
    jPanel2.setBorder(javax.swing.BorderFactory.createTitledBorder(null, "Contact Information", javax.swing.border.TitledBorder.DEFAULT_JUSTIFICATION, javax.swing.border.TitledBorder.DEFAULT_POSITION, new java.awt.Font("Tahoma", 1, 12), java.awt.Color.white)); // NOI18N
    jPanel2.setForeground(new java.awt.Color(255, 255, 255));
    jPanel2.setLayout(new java.awt.GridBagLayout());

    jLabel8.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
    jLabel8.setForeground(new java.awt.Color(255, 255, 255));
    jLabel8.setText("Phone Number :");
    jPanel2.add(jLabel8, new java.awt.GridBagConstraints());

    textHomePhone.setPreferredSize(new java.awt.Dimension(100, 20));
    jPanel2.add(textHomePhone, new java.awt.GridBagConstraints());

    jLabel9.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
    jLabel9.setForeground(new java.awt.Color(255, 255, 255));
    jLabel9.setText("Mobile Phone :");
    gridBagConstraints = new java.awt.GridBagConstraints();
    gridBagConstraints.gridx = 0;
    jPanel2.add(jLabel9, gridBagConstraints);

    textMobilePhone.setPreferredSize(new java.awt.Dimension(100, 20));
    gridBagConstraints = new java.awt.GridBagConstraints();
    gridBagConstraints.gridx = 1;
    gridBagConstraints.gridy = 1;
    jPanel2.add(textMobilePhone, gridBagConstraints);

    jLabel10.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
    jLabel10.setForeground(new java.awt.Color(255, 255, 255));
    jLabel10.setText("Email :");
    gridBagConstraints = new java.awt.GridBagConstraints();
    gridBagConstraints.gridx = 0;
    gridBagConstraints.gridy = 2;
    jPanel2.add(jLabel10, gridBagConstraints);

    textEmail.setToolTipText("");
    textEmail.setMaximumSize(new java.awt.Dimension(100, 27));
    textEmail.setMinimumSize(new java.awt.Dimension(100, 20));
    textEmail.setPreferredSize(new java.awt.Dimension(100, 20));
    gridBagConstraints = new java.awt.GridBagConstraints();
    gridBagConstraints.gridx = 1;
    gridBagConstraints.gridy = 2;
    jPanel2.add(textEmail, gridBagConstraints);

    buttonAddClient.setBackground(new java.awt.Color(204, 153, 0));
    buttonAddClient.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
    buttonAddClient.setForeground(new java.awt.Color(153, 0, 0));
    buttonAddClient.setText("Add Client Now");
    buttonAddClient.setFocusable(false);
    buttonAddClient.setHorizontalAlignment(javax.swing.SwingConstants.LEFT);
    buttonAddClient.setHorizontalTextPosition(javax.swing.SwingConstants.CENTER);
    buttonAddClient.setInheritsPopupMenu(true);
    buttonAddClient.setVerticalTextPosition(javax.swing.SwingConstants.BOTTOM);
    buttonAddClient.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            buttonAddClientActionPerformed(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, false)
                .addGroup(jPanel1Layout.createSequentialGroup()
                    .addComponent(jLabel1)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                    .addComponent(textClientNo, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGroup(jPanel1Layout.createSequentialGroup()
                    .addComponent(jLabel4)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                    .addComponent(textStreetAddress, javax.swing.GroupLayout.PREFERRED_SIZE, 352, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGroup(jPanel1Layout.createSequentialGroup()
                    .addComponent(jLabel2)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                    .addComponent(textFName, javax.swing.GroupLayout.PREFERRED_SIZE, 91, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGap(31, 31, 31)
                    .addComponent(jLabel3)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addComponent(textLName))
                .addGroup(jPanel1Layout.createSequentialGroup()
                    .addComponent(jLabel5)
                    .addGap(18, 18, 18)
                    .addComponent(textCity, javax.swing.GroupLayout.PREFERRED_SIZE, 97, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGap(40, 40, 40)
                    .addComponent(jLabel6)
                    .addGap(18, 18, 18)
                    .addComponent(comboStatebox, javax.swing.GroupLayout.PREFERRED_SIZE, 80, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGap(18, 18, 18)
                    .addComponent(jLabel7)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addComponent(textZipCode, javax.swing.GroupLayout.PREFERRED_SIZE, 46, javax.swing.GroupLayout.PREFERRED_SIZE)))
            .addContainerGap(267, Short.MAX_VALUE))
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
            .addComponent(jPanel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addContainerGap())
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addComponent(buttonAddClient)
            .addGap(279, 279, 279))
    );
    jPanel1Layout.setVerticalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel1Layout.createSequentialGroup()
            .addGap(40, 40, 40)
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(textClientNo, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(jLabel1))
            .addGap(18, 18, 18)
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(jLabel2)
                .addComponent(textFName, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(jLabel3)
                .addComponent(textLName, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addGap(18, 18, 18)
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(jLabel4)
                .addComponent(textStreetAddress, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addGap(18, 18, 18)
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(jLabel5)
                .addComponent(textCity, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(jLabel6)
                .addComponent(comboStatebox, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(jLabel7)
                .addComponent(textZipCode, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addGap(30, 30, 30)
            .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, 100, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(18, 18, 18)
            .addComponent(buttonAddClient)
            .addContainerGap())
    );

    add(jPanel1, java.awt.BorderLayout.CENTER);
}// </editor-fold>

private void buttonAddClientActionPerformed(java.awt.event.ActionEvent evt) {                                         
    // TODO add your handling code here:
    //card.show(panelMain, PANEL_SQLDB_RESULT);

    //SQLModule sqlModule = new SQLModule();
    //this.appEventListener = appEventListener;

    //JOptionPane.showMessageDialog(null, "Button Add Client Clicked On", "Client ADD Button Click", JOptionPane.ERROR_MESSAGE);

    String clientNo = textClientNo.getText();
    String clientFName = textFName.getText();
    String clientLName = textLName.getText();

    if (clientNo.equals("")) {
        JOptionPane.showMessageDialog(this, "You must enter a Client Number (Client ID).", "Error", JOptionPane.ERROR_MESSAGE);
        textClientNo.requestFocus();
        return;
    }


    System.out.print("JUST BEFORE APP-EVENT " + clientNo + " was HIT!");

    //appEventListener.buttonAddClientActionPerformed(clientNo, clientFName, clientLName);

    if (appEventListener != null) {

        System.out.print(" appEventListener " + clientNo + " was Secondly HIT!");
        appEventListener.buttonAddClientActionPerformed(clientNo, clientFName, clientLName);
    }   

}           

<小时/>

这就是我得到空指针(或缺少空指针)的地方..，由于 appEventListener 为空，因此该代码永远不会被执行。

<小时/>

if (appEventListener != null) {

    System.out.print(" appEventListener " + clientNo + " was Secondly HIT!");
    appEventListener.buttonAddClientActionPerformed(clientNo, clientFName, clientLName);
} 

异常跟踪:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at com.zflex.cims.panels.PanelAddClient.buttonAddClientActionPerformed(PanelAddClient.java:297)
    at com.zflex.cims.panels.PanelAddClient.access$000(PanelAddClient.java:16)
    at com.zflex.cims.panels.PanelAddClient$1.actionPerformed(PanelAddClient.java:181)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
    at java.awt.Component.processMouseEvent(Component.java:6038)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3260)
    at java.awt.Component.processEvent(Component.java:5803)
    at java.awt.Container.processEvent(Container.java:2058)
    at java.awt.Component.dispatchEventImpl(Component.java:4410)
    at java.awt.Container.dispatchEventImpl(Container.java:2116)
    at java.awt.Component.dispatchEvent(Component.java:4240)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3986)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
    at java.awt.Container.dispatchEventImpl(Container.java:2102)
    at java.awt.Window.dispatchEventImpl(Window.java:2429)
    at java.awt.Component.dispatchEvent(Component.java:4240)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)

就在 APP-EVENT 6565 即将结束之前

<小时/>

这来自抽象的App Listener模块

public interface AppEventListener {

    public void buttonAddClientActionPerformed(String clientNo, String clientFName, String clientLName);

    //void buttonDisplayRawLDAPStatsActionPerformed();
}

Answer 1

您声明了事件监听器，但从未像这样初始化它:

private AppEventListener appEventListener = new AppEventListener();

在使用之前声明它(例如在 initComponet() 中)