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(); System.out.println("Client connected."); BufferedReader in = new Bu
In Java, an interface reference variable can be used to refer to objects of classes that implement the interface. This allows for polymorphism and flexibility in designing code. Here's how it works:
1. Declaring Interface Reference:
MyInterface obj;
Here, `MyInterface` is the interface, and `obj` is a reference variable of type `MyInterface`.
2. Assigning Objects:
obj = new MyClass(); // MyClass implements MyInterface
The `obj` reference variable can point to any object of a class that implements the `MyInterface` interface.
3. Accessing Methods:
obj.method(); // Calls method() implemented in MyClass
Through the interface reference variable, you can call methods declared in the interface. The actual implementation of the method depends on the class to which `obj` is currently referring.
Example:
// Interface definition
interface MyInterface {
void method();
}
// Class implementing the interface
class MyClass implements MyInterface {
public void method() {
System.out.println("Method implementation in MyClass");
}
}
public class Main {
public static void main(String[] args) {
// Interface reference pointing to MyClass object
MyInterface obj = new MyClass();
obj.method(); // Calls method() implemented in MyClass
}
}
Explanation:
- In this example, `MyClass` implements the `MyInterface` interface.
- We declare an interface reference variable `obj` of type `MyInterface`.
- We instantiate a `MyClass` object and assign it to `obj`.
- Through the `obj` reference variable, we call the `method()` defined in the `MyInterface` interface.
- At runtime, the JVM invokes the `method()` implemented in `MyClass`.
Benefits:
- Interface references provide flexibility in code design by allowing objects of different classes to be treated uniformly.
- They support polymorphism, allowing method calls to be resolved dynamically at runtime based on the actual object type.
- Interfaces facilitate loose coupling and abstraction, enhancing code maintainability and extensibility.
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