Java Basics - Interview Questions and Answers

  1. Primitive data types are passed by reference or pass by value?
    Primitive data types are passed by value.
  2. Objects are passed by value or by reference?
    Java only supports pass by value. With objects, the object reference itself is passed by value and so both the original reference and parameter copy both refer to the same object.
  3. What is serialization?
    Serialization is a mechanism by which you can save the state of an object by converting it to a byte stream.
  4. How do I serialize an object to a file?
    The class whose instances are to be serialized should implement an interface Serializable. Then you pass the instance to the ObjectOutputStream which is connected to a fileoutputstream. This will save the object to a file.
  5. Which methods of Serializable interface should I implement?
    The serializable interface is an empty interface, it does not contain any methods. So we do not implement any methods.
  6. How can I customize the seralization process? i.e. how can one have a control over the serialization process?

    Yes it is possible to have control over serialization process. The class should implement Externalizable interface. This interface contains two methods namely readExternal and writeExternal.

    You should implement these methods and write the logic for customizing the serialization process.

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