java.lang.reflect.InvocationTargetException ：这是什么原因？答案

【问题标题】：java.lang.reflect.InvocationTargetException : what is the reason for this?java.lang.reflect.InvocationTargetException ：这是什么原因？
【发布时间】：2012-07-08 21:50:42
【问题描述】：

当我尝试运行小程序时出现以下异常：

java.lang.reflect.InvocationTargetException
at com.sun.deploy.util.DeployAWTUtil.invokeAndWait(Unknown Source)
at sun.plugin2.applet.Plugin2Manager.runOnEDT(Unknown Source)
at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.RuntimeException: java.lang.IllegalAccessException: Class sun.plugin2.applet.Plugin2Manager$12 can not access a member of class MyApplet with modifiers ""
at sun.plugin2.applet.Plugin2Manager$12.run(Unknown Source)
at java.awt.event.InvocationEvent.dispatch(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)
    Caused by: java.lang.IllegalAccessException: Class sun.plugin2.applet.Plugin2Manager$12 can not access a member of class MyApplet with modifiers ""
at sun.reflect.Reflection.ensureMemberAccess(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
... 9 more

异常：java.lang.reflect.InvocationTargetException

小程序代码：

import javax.swing.*;
import java.awt.*;

class MyApplet extends JApplet {

public JFrame frame;
public JPanel panel;
public JButton button;

public void init() {
    frame = new JFrame();
    panel = new JPanel();
    button = new JButton("click me ");
    panel.setBackground(Color.RED);
    panel.add(button);
    frame.add(panel);
    frame.setSize(300,300);
    frame.setVisible(true);
}   
 }

HTML 文件：

<applet code="MyApplet" codebase="AppletPackage" archive="JAR.jar" height="800" width="800">

JAR.jar 包含一个名为 AppletPackage 的包，其中包含 MyApplet 类。它还包含自动添加的清单文件。

有什么问题？

【问题讨论】：

标签： java html jar applet

【解决方案1】：

InvocationTargetException 表明某些反射调用失败。似乎某些 Sun (Oracle) 类正在尝试使用反射来访问您代码中的类。

您的课程 MyApplet 没有 public 范围修饰符。如果你添加它，我希望一切都会奏效，因为这就是异常所抱怨的。

原因：java.lang.IllegalAccessException: Class sun.plugin2.applet.Plugin2Manager$12 无法使用修饰符“”访问 MyApplet 类的成员

【讨论】：