使用反射调用 PumpEvents 时出现 java.lang.illegalArgumentException

Question

我正在尝试在 Java Applet 中制作模态框架，如下所示:http://www.java2s.com/Tutorial/Java/0240__Swing/Showthegivenframeasmodaltothespecifiedowner.htm 。这段代码有 start() 函数，看起来像

public void start() throws Exception {
  Class<?> clazz = Class.forName("java.awt.Conditional");
  Object conditional = Proxy.newProxyInstance(clazz.getClassLoader(), new Class[] { clazz },
      this);
  Method pumpMethod = Class.forName("java.awt.EventDispatchThread").getDeclaredMethod(
      "pumpEvents", new Class[] { clazz });
  pumpMethod.setAccessible(true);
  pumpMethod.invoke(Thread.currentThread(), new Object[] { conditional });
}.

当我打电话时

 pumpMethod.invoke(Thread.currentThread(), new Object[] { conditional });

我有以下异常:

    java.lang.RuntimeException: java.lang.IllegalArgumentException: object is not an instance of declaring class
    at wizard.ModalFrameUtil.showAsModal(ModalFrameUtil.java:136)
    at wizard.WizardCore.showWizardFrame(WizardCore.java:206)
    at SelfRegistrationApplet$1.run(SelfRegistrationApplet.java:55)
    at SelfRegistrationApplet$1.run(SelfRegistrationApplet.java:35)
    at java.security.AccessController.doPrivileged(Native Method)
    at SelfRegistrationApplet.RunSelfRegistrationApplet(SelfRegistrationApplet.java:32)
    at SelfRegistrationApplet.init(SelfRegistrationApplet.java:26)
    at sun.applet.AppletPanel.run(AppletPanel.java:424)
    at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.IllegalArgumentException: object is not an instance of declaring class
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at wizard.ModalFrameUtil$EventPump.start(ModalFrameUtil.java:80)
    at wizard.ModalFrameUtil.showAsModal(ModalFrameUtil.java:133)
    ... 8 more

您能否告诉我此调用中有什么问题以及如何避免此异常？

Answer 1

它的意思是 Thread.currentThread() 返回的 Thread 对象不是 EventDispatchThread 的实例。

避免这个问题的方法是找出该对象的真正类是什么，并使用那个类来获取Method对象。 (您应该能够通过在尝试调用该方法的位置打印从 Thread.currentThread().getClass() 获取的对象来找出它是什么。

<小时/>

invoke 的 Javadoc 是这样说的:

"Throws IllegalArgumentException - if the method is an instance method and the specified object argument is not an instance of the class or interface declaring the underlying method (or of a subclass or implementor thereof); if the number of actual and formal parameters differ; if an unwrapping conversion for primitive arguments fails; or if, after possible unwrapping, a parameter value cannot be converted to the corresponding formal parameter type by a method invocation conversion."

我对您的代码的解读是，您拥有正确数量和类型的实际参数，因此这一定是线程类的问题。