Null 指針異常錯誤 java 按鈕 java

Question

每次我嘗試輸入 email 密碼的詳細信息並命名它時，按鈕上都會出現 null 指針異常。

但是，數據庫上的所有內容也是有效的，並且連接也建立了，但是我按下添加會計按鈕后出現錯誤。

我試圖檢查我的數據庫連接代碼一切都很好，我的連接變量也被初始化了。

private void addbtn2ActionPerformed(java.awt.event.ActionEvent evt) {                                        

    try {


        PreparedStatement stmt = con.prepareStatement("INSERT INTO accountant('email','password','name')VALUES(?,?,?)");

        String names=namef2.getText();
        String emails=emailf2.getText();
        String passwords=String.valueOf(jPasswordField2.getText());
        String c_p=String.valueOf(jPasswordField2.getText());
        stmt.setString(1, emails);
        stmt.setString(2, passwords);
        stmt.setString(3, names);
        JOptionPane.showMessageDialog(null,"Accountant Successfully added");
        stmt.execute();
        stmt.close();

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

Output

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at Admin.panel.AccountantDetails.addbtn2ActionPerformed(AccountantDetails.java:300)
at Admin.panel.AccountantDetails.access$300(AccountantDetails.java:15)
at Admin.panel.AccountantDetails$4.actionPerformed(AccountantDetails.java:186)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
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:6539)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6304)
at java.awt.Container.processEvent(Container.java:2239)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2297)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4904)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4535)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4476)
at java.awt.Container.dispatchEventImpl(Container.java:2283)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:84)
at java.awt.EventQueue$4.run(EventQueue.java:733)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
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)

BUILD SUCCESSFUL (total time: 11 seconds)

Answer 1

如果這是按鈕點擊動作

私人無效addbtn2ActionPerformed（java.awt.event.ActionEvent evt）{

那么參數應該是 View 而不是 ActionEvent。