JDK-8059590 : ArrayIndexOutOfBoundsException occurs when Container with overridden getComponents() is deserialized
  • Type: Bug
  • Component: client-libs
  • Sub-Component: java.awt
  • Affected Version: 8u20
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2014-10-02
  • Updated: 2015-06-04
  • Resolved: 2014-10-20
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JDK 8 JDK 9
8u40Fixed 9 b38Fixed
Related Reports
Relates :  
JDK-6784816 - Remove AWT tree lock from Container methods: getComponent, getComponents, getComponentCount
Description
If a subclass of java.awt.Container overrides getComponents(), and the object with overridden getComponents() is serialized and then deserialized, ArrayIndexOutOfBoundsException occurs.

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
        at java.awt.Container.readObject(Container.java:3733)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:483)
        at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1896)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:371)
        at a.main(a.java:17)

This problem does not occur in jdk6u81. This seems to be a regression.
Comments
Regression was introduced by JDK-6784816 which is very old to analyze.
06-04-2015
Root cause: Container.writeObject directly accesses component.size() to write "ncomponents" field but it uses getComponentsSync() method when writing "component" field. This method eventually calls public method getComponents(). Since getComponents() is overridden to return an empty array, the number of "expected" components in "ncomponents" and the length of "component" array differs which causes ArrayIndexOutOfBoundsException when readObject tries to copy the read "component" array into internal component list.
16-10-2014
Proposed fix: Use component.toArray(EMPTY_ARRAY) to serialize "component" field. This approach preserves the internal state of Container object: if a component is added into Container, it will be in the Container after the object is deserialized. If serialization code uses getComponents() or getComponentsSync() to write both "ncomponents" and "component" fields, then components added via add() method will be lost after deserialization.
16-10-2014