What is externalization in Java with examples?
Externalization is used whenever we need to customize serialization mechanism. If a class implements an Externalizable interface then, object serialization will be done using writeExternal() method. Below example showcases usage of Externalizable interface.
What is difference between serialization and externalization in java?
A serializable interface is used to implement serialization. Serializable is a marker interface i.e. it does not contain any method. The externalizable interface is not a marker interface and thus it defines two methods writeExternal() and readExternal(). Default serialization does not require any no-arg constructor.
Which of the following is best case to use the externalization interface in Java?
If you want to serialize only part of an object, then Externalization is the best option. You will have to serialize only required fields of an object.
What is the significance of SerialVersionUID in Java?
The serialization at runtime associates with each serializable class a version number called a serialVersionUID, which is used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible with respect to serialization.
Can we create a marker interface in java?
You can write your own Marker interface ,JVM do not know anything about it. A marker interface is an empty interface. This mean you just need to create a interface and do not create any method in it.
Why do we use marker interface in java?
Marker interface is used as a tag to inform a message to the Java compiler so that it can add special behaviour to the class implementing it. When a Java class is to be serialized, you should intimate the Java compiler in some way that there is a possibility of serializing this java class.
What is functional interface in Java?
A functional interface in Java is an interface that contains only a single abstract (unimplemented) method. A functional interface can contain default and static methods which do have an implementation, in addition to the single unimplemented method.
Can two classes have same serialVersionUID?
Yes, you can. Serial versions of different classes are independent and do not interfere each other. Eclipse even proposes you to set serialVersionID by default value that is 1L . serialVersionUID is needed to remember versions of the class.
Is serialVersionUID mandatory in Java?
Defining a serialVersionUID field in a serializable class is not mandatory. If there is no serialVersionUID field defined explicitly then serialization runtime will calculate default value for that class. The value can vary based on compiler implementation. Hence it is advisable to define serialVersionUID.
What is methods in Java with example?
A Java method is a collection of statements that are grouped together to perform an operation. When you call the System. out. println() method, for example, the system actually executes several statements in order to display a message on the console.