The AWT Component class implements the java.io.Serializable marker interface, and JComponent reimplements this interface. This means that all AWT and Swing components are serializable, or, in other words, the state of an AWT or Swing component can be stored as a stream of bytes that can be written to a file. Components serialized to a file can be restored to their original state at a later date. When a component is serialized, all the components it contains are also automatically serialized as part of the same stream.
You serialize a component (or any serializable object) with the java.io. ObjectOutputStream class and reconstruct a serialized component with the java.io.ObjectInputStream. See Java in a Nutshell for more information about these classes. Because the byte stream format used in serialization changed between Java 1.1 and Java 1.2, Swing components serialized by a Java 1.2 application cannot be deserialized by a Java 1.1 application.
The serializability of Swing and AWT components is a powerful feature that is exploited by some GUI design tools. Thus, an application may create its graphical interface simply by reading and deserializing an already-built interface from a file. This is usually much simpler than creating the components of the GUI individually.
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