java - 使用java swing更新sql上的数据

Question

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已关闭 10 年前。

我的代码有问题，不知道如何修复它，因为我一遍又一遍地这样做......并且发生了同样的错误，谁能告诉我该怎么办？

这是我的代码:

对于我的连接路径:

public void Connection(String path){
    try{
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            String url = "jdbc:odbc:*****";
            String user = "*****";
            String pass = "*****";
            connection =  DriverManager.getConnection(url, user, pass);
} catch(Exception e) {}}

我的更新代码:

try{
            String update = ("UPDATE dbo.Patients set pLName=?,pFName=? where pIDNo" +txtPatientID.getText()+"");
            ps = connection.prepareStatement(update);
            ps.setString(1, txtpFName.getText());
            ps.setString(2, txtpLName.getText());
            ps.execute();
            }
            catch(Exception e)
            {
            e.printStackTrace();
            System.exit(1);
            }

这是我遇到的错误:

java.lang.NullPointerException
    at javaapplication25.EditPatient.btnUpdateActionPerformed(EditPatient.java:407)
    at javaapplication25.EditPatient.access$100(EditPatient.java:14)
    at javaapplication25.EditPatient$2.actionPerformed(EditPatient.java:187)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    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:6505)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6270)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4861)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2713)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
    at java.awt.EventQueue.access$000(EventQueue.java:101)
    at java.awt.EventQueue$3.run(EventQueue.java:666)
    at java.awt.EventQueue$3.run(EventQueue.java:664)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:680)
    at java.awt.EventQueue$4.run(EventQueue.java:678)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
Java Result: 1

Answer 1

如果您的异常发生在这一行

ps.setString(2, txtpLName.getText());

看起来 txtplName 是 null，因为您的代码已经调用了 ps 的方法。

但是你应该真正投资于你的异常处理，否则你总是会遇到这样的“后续”错误。特别是在 Connection 方法中吞下异常可能会让您感到困扰，因为您不会看到连接尚未建立。打印堆栈跟踪有助于调试，但对您的应用程序没有帮助。至少返回 true 或 false 并进行相应处理(false 意味着您无法建立连接，因此您不需要继续) .