AbstractButton abstractButton = (AbstractButton) changeEvent.getSource(); ButtonModel buttonModel = abstractButton.getModel(); boolean pressed = buttonModel.isPressed();这段代码什么意思？

这段代码是用于监听按钮状态变化的事件处理程序，首先获取事件源对象，即发生状态变化的按钮对象，然后通过该按钮对象获取其对应的按钮模型对象，最后判断按钮是否被按下并获取该状态的布尔值。具体来说，这段代码中的 `AbstractButton`、`ButtonModel` 和 `isPressed()` 方法都是 Java Swing 中的类和方法，用于处理按钮的状态和事件。

相关问题

abstractbutton

AbstractButton是一个抽象基类，提供了按钮组件的通用功能。在Qt中，AbstractButton类被继承并实现了一系列具体的按钮组件，如Button、CheckBox、RadioButton等。\[1\]在Swing中，AbstractButton类也是按钮组件的基类，常见的按钮组件如JButton、JCheckBox、JRadioButton等都是AbstractButton类的子类或间接子类。\[2\]AbstractButton类提供了一些常用的方法，如获取和设置按钮的图标、文本，启用或禁用按钮，设置按钮的选中状态等。\[2\]在Qt中，可以使用ButtonGroup来管理一组按钮，当点击组中的按钮时，会发出一个信号，方便为同一组中的所有按钮实现公共的信号处理程序。\[3\]
#### 引用[.reference_title]
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[ .reference_list ]

java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES) select * from usertable where UserName='汪汪队'and Password='1012' Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at DBConn.DataBaseManager.getResult(DataBaseManager.java:31) at Forms.UserLogin.actionPerformed(UserLogin.java:76) at javax.swing.AbstractButton.fireActionPerformed(Unknown Source) at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source) at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source) at javax.swing.DefaultButtonModel.setPressed(Unknown Source) at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source) at java.awt.Component.processMouseEvent(Unknown Source) at javax.swing.JComponent.processMouseEvent(Unknown Source) at java.awt.Component.processEvent(Unknown Source) at java.awt.Container.processEvent(Unknown Source) at java.awt.Component.dispatchEventImpl(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source) at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source) at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Window.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.EventQueue.dispatchEventImpl(Unknown Source) at java.awt.EventQueue.access$500(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue$4.run(Unknown Source) at java.awt.EventQueue$4.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue.dispatchEvent(Unknown Source) at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.run(Unknown Source)这个报错怎么解决

这个报错是由于使用指定的用户名和密码无法连接到本地 MySQL 数据库引起的，可能是因为用户名或密码不正确或者没有给这个用户授权访问该数据库的权限。解决这个问题的方法如下：

1. 确认用户名和密码是否正确，并且是否有权限访问该数据库。
2. 确认 MySQL 服务是否已经启动，如果没有，请启动它。
3. 如果你使用的是 localhost 作为主机名，请尝试使用 127.0.0.1 来替换它，因为在某些情况下，localhost 会出现一些问题。
4. 如果仍然无法解决问题，请检查防火墙设置是否阻止了 MySQL 数据库的访问，如果是，请允许 MySQL 数据库的访问。
5. 如果以上方法都无法解决问题，请检查你的代码是否正确，你可以尝试使用其他的 MySQL 客户端来连接到数据库，看是否能够成功连接。