What is the use of transient variables?

java serialization transient
muralidhar picture muralidhar · May 11, 2011 · Viewed 13.1k times · Source

Possible Duplicate:
Why does Java have transient variables?

The transient keyword will be used to prevent serialization of a particular variable. But why should we not to serialize the data? Is there any inner security?

Answer

Joachim Sauer picture Joachim Sauer · May 11, 2011

Some classes are inherently not serializable, because they represent resources outside of the manage Java environment. For example a FileOutputStream can't really be serialized, because it represents an open file handle. The same is true for a Socket: you can't save and restore "open sockets".

If you want to serialize some object that has a field of that type, then you'll have to mark those fields as transient.

Another reason to use transient is when your class does some kind of internal caching. If, for example, your class can do calculations and for performance reasons it caches the result of each calculation, then saving that cache might not be desirable (because recalculating it might be faster than restoring it, or because it's unlikely that old cached values are of any use). In this case you'd mark the caching fields as transient.

Related questions

Why use the `transient` keyword in java?

I have an issue related to the transient keyword's use before the private modifier in java . variable declaration: transient private ResourceBundle pageResourceBundle; My class looks like this : public class LoginViewModel extends AbstractViewModel { transient private ResourceBundle pageResourceBundle; @AfterCompose public void afterCompose(@…

Read More
How does marking a field as transient make it possible to serialise an object

public class Foo implements java.io.Serializable { private int v1; private static double v2; private Loan v3 = new Loan(); } Options: A. An instance of Foo can be serialized because Foo implements Serializable. B. An instance of Foo cannot be serialized …

Read More
Java static serialization rules?

I'm working on a save state serialization with a few static methods and fields. I could have sworn though that serialization and static's caused mayhem. Should I make all static's transient? And will inflating the calls restore the statics as …

Read More