What Interface Must an Object Implement Before it Can be Written to a Stream as an Object

An object must implement the Serializable or Externalizable interface before it can be written to a stream as an object.

In Java, for an object to be written to a stream as an object, it must implement the Serializable interface. The Serializable interface is a marker interface, meaning it doesn’t declare any methods. Its purpose is to indicate to the Java runtime that the class can be serialized, i.e., its state can be converted into a byte stream and later reconstructed.

Here’s an example of a class implementing the Serializable interface:

By implementing Serializable, you are telling the Java runtime that it’s safe to serialize instances of your class. Keep in mind that not all objects can or should be serialized; for example, objects that manage resources like threads or file handles may not serialize properly without additional considerations.