Lessons Learned

1. Object Serialization: Understand how to serialize and deserialize objects in Java using ObjectOutputStream and ObjectInputStream.

2. Stream Order: Remember the order of stream creation:

"Always create ObjectOutputStream before ObjectInputStream".

This is crucial to avoid EOFException when reading from the input stream.

3. Avoid mixing ObjectOutputStream and DataOutputStream.:use one or the other.

4. Different Types of Streams: Familiarize with different types of streams: FileInputStream, FileOutputStream, ObjectInputStream, and ObjectOutputStream.

5. Only create single ObjectOutput and ObjectInput stream per Socket: results in StreamCorruptedException.

6. Closing Streams closes Sockets

7. Sync between Client and Server: Understand the importance of synchronization between client and server when sending and receiving objects. The server should be ready to receive an object before the client sends it.

TODOs:

• Smooth msg exchange between client and server.

• Multiple clients support.

  • add a new thread for each client.
  • store username and out streams in a map.

• support to send files over the network.

• add a database to store user credentials and messages.

• add user authentication.

• add encryption to the messages.

• add a GUI to the client.