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POSkipping over newly-transient fields when deserializing
 

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    <p>I inherited the following code (and data stored using it, i.e. serialized instances of A):</p> <pre><code>class A implements Serializable { private static final long serialVersionUID = 1L; int someField; B b; } class B implements Serializable { private static final long serialVersionUID = 1L; int someField; } </code></pre> <p>At some point I realized that the <code>b</code> field in <code>A</code> should not actually be persisted (and <code>B</code> shouldn't be serializable at all), so I changed things to:</p> <pre><code>class A implements Serializable { private static final long serialVersionUID = 1L; int someField; transient B b; } class B { int someField; } </code></pre> <p>If I make a new instance of <code>A</code> and serialize it, I have no trouble deserializing it. However, if I try to deserialize instances of <code>A</code> that were stored with the old code, I get an exception of the form:</p> <pre><code>java.io.InvalidClassException: B; B; class invalid for deserialization at java.io.ObjectStreamClass.checkDeserialize(Unknown Source) at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source) at java.io.ObjectInputStream.readObject0(Unknown Source) at java.io.ObjectInputStream.defaultReadFields(Unknown Source) at java.io.ObjectInputStream.readSerialData(Unknown Source) at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source) at java.io.ObjectInputStream.readObject0(Unknown Source) at java.io.ObjectInputStream.readObject(Unknown Source) </code></pre> <p>I believe this is because the persisted data also has <code>A</code>'s and <code>B</code>'s class descriptions stored, and those still think that <code>b</code> is persisted, even if in the current version they no longer are (see lines 600 to 606 in <a href="http://hg.openjdk.java.net/jdk6/jdk6-gate/jdk/file/80266a3303b2/src/share/classes/java/io/ObjectStreamClass.java" rel="nofollow noreferrer">ObjectStreamClass</a>)</p> <p>Is there a way to force A's deserialization to skip over fields that are now transient? For example, is there a way to override the class description that the deserialization code reads in <code>ObjectInputStream</code> and update its definition of <code>b</code> so that it knows its transient?</p>
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    1. USMihai Parparita
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