Socket communication in Java enables communication between two endpoints over a network. There are two main types of sockets: TCP sockets and UDP sockets. Let's explain both types with examples: TCP Socket Communication: 1. **Server Side**: - The server creates a `ServerSocket` object to listen for incoming connections on a specific port. - When a client connects, the server accepts the connection and creates a `Socket` object to communicate with the client. - The server reads from and writes to the socket's input and output streams to communicate with the client. import java.io.*; import java.net.*; public class TCPServer { public static void main(String[] args) throws IOException { ServerSocket serverSocket = new ServerSocket(12345); System.out.println("Server started. Waiting for client..."); Socket clientSocket = serverSocket.accept(); ...
In Java, you can create custom exceptions by extending the `Exception` class or one of its subclasses like `RuntimeException`. Custom exceptions are useful when you want to define your own exception types to represent specific error conditions in your application.
Syntax for creating a custom exception:
public class CustomException extends Exception {
// Constructors, methods, and additional members can be defined here
}
Example of a custom exception:
public class InvalidAgeException extends Exception {
public InvalidAgeException(String message) {
super(message);
}
}
public class AgeValidator {
public static void validateAge(int age) throws InvalidAgeException {
if (age < 0) {
throw new InvalidAgeException("Age cannot be negative");
}
if (age < 18) {
throw new InvalidAgeException("Must be at least 18 years old");
}
System.out.println("Age is valid");
}
public static void main(String[] args) {
try {
validateAge(20);
validateAge(-5); // This will throw an InvalidAgeException
} catch (InvalidAgeException e) {
System.out.println("InvalidAgeException: " + e.getMessage());
}
}
}
In this example:
- We create a custom exception `InvalidAgeException` by extending the `Exception` class and providing a constructor to set the error message.
- The `validateAge` method throws `InvalidAgeException` if the age is negative or less than 18.
- In the `main` method, we catch `InvalidAgeException` and handle it appropriately.
Analogy:
Think of a custom exception as a specialized tool or equipment designed for a specific task. For example, in a carpentry workshop, if you encounter a particular type of material that requires a unique cutting technique, you might design a custom saw blade specifically for that material. Similarly, in Java, custom exceptions allow you to create specialized error-handling mechanisms tailored to specific error conditions in your application.
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