Java Interview Questions

HashSet extends AbstractSet and implements the Set interface. It creates a collection that uses a hash table for storage. As most readers likely know, a hash table stores information by using a mechanism called hashing. In hashing, the informational content of a key is used to determine a unique value, called its hash code. The [...]

Note:
Establishing Communication between a Server and a Client through a socket is called Socket Programming

To create the Client Socket Socket Class is available in java.net package.
To create ServerSocket, ServerSocket class is avialable in java.net package
A Client is a machine that sends a request for some service
A Server is machine that provides services to the client

Note:  [...]

When a new Socket is created new port number should be allocated.
When the service on the same socket is changed, a new port number should be alloted.
Note :- Some alloted port numbers :
port no. Application
13                                    Date and time Services
21                                    FTP,Which transfers files
23                                   Telnet,Which provides remote login
25                                   SMTP,Which delivers mail messages
67                                   BOOTP,Which provides configuration at  boot [...]

Rep) Sets (or) set Classes will not allow duplicate values