ObjectInput

ObjectInput is an interface in Java's input/output API that extends the DataInput interface. It provides methods for reading primitive data types and objects from a data stream. The primary purpose of ObjectInput is to deserialize Java objects, meaning it reconstructs a Java object from a sequence of bytes. This is a fundamental part of Java's object serialization mechanism.

When an object is serialized, its state is written to an output stream. ObjectInput is used on the receiving end to read this stream and reconstruct the original object. The core method for deserialization is readObject(), which reads a serialized object from the input stream and returns it as an Object. The caller is then responsible for casting this Object to its appropriate type.

ObjectInput is typically implemented by classes like ObjectInputStream. When using ObjectInputStream, it's crucial to ensure that the stream is properly closed after use to release system resources. This is often achieved using a try-with-resources statement. The deserialization process can be computationally intensive and is a common target for performance optimizations and security vulnerabilities if not handled carefully. It's essential to deserialize only from trusted sources to prevent potential security risks.