为什么要System.out.println(e.getCause());给出null？

并且可以像这样存储整个HashSet集合吗？

private void saving() throws IOException, ClassNotFoundException {

ObjectOutputStream out = null;

try {

out = new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream(dataFile)));

out.writeObject(c);

} catch (java.io.NotSerializableException e) {

System.out.println(e.getCause());

} finally {

out.close();

}

}

使用printStackTrace()而不是getCause()

java.io.NotSerializableException: Data$1

at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1180)

at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1528)

at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1493)

at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1416)

at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)

at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:346)

at java.util.HashSet.writeObject(HashSet.java:284)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:616)

at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:962)

at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1480)

at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1416)

at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)

at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:346)

at Prozor.saving(Prozor.java:81)

at Prozor.actionPerformed(Prozor.java:57)

at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2012)

at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2335)

at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:404)

at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)

at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:253)

at java.awt.Component.processMouseEvent(Component.java:6268)

at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)

at java.awt.Component.processEvent(Component.java:6033)

at java.awt.Container.processEvent(Container.java:2045)

at java.awt.Component.dispatchEventImpl(Component.java:4629)

at java.awt.Container.dispatchEventImpl(Container.java:2103)

at java.awt.Component.dispatchEvent(Component.java:4455)

at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4633)

at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4297)

at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4227)

at java.awt.Container.dispatchEventImpl(Container.java:2089)

at java.awt.Window.dispatchEventImpl(Window.java:2517)

at java.awt.Component.dispatchEvent(Component.java:4455)

at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:649)

at java.awt.EventQueue.access$000(EventQueue.java:96)

at java.awt.EventQueue$1.run(EventQueue.java:608)

at java.awt.EventQueue$1.run(EventQueue.java:606)

at java.security.AccessController.doPrivileged(Native Method)

at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:105)

at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:116)

at java.awt.EventQueue$2.run(EventQueue.java:622)

at java.awt.EventQueue$2.run(EventQueue.java:620)

at java.security.AccessController.doPrivileged(Native Method)

at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:105)

at java.awt.EventQueue.dispatchEvent(EventQueue.java:619)

at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:275)

at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:200)

at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)

at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:185)

at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:177)

at java.awt.EventDispatchThread.run(EventDispatchThread.java:138)

仍然没有看到问题,除了它在第一个集合对象上占用,并且集合正在实现Serializable,所有对象也实现Serializable并且线程具有瞬态声明