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(); ...
Input and output (I/O) in Java involve the process of receiving data into a program (input) and sending data out of a program (output). Here's an overview of input and output in Java:
Input in Java:
1. Reading from Console:
- Java provides the `Scanner` class to read input from the console.
import java.util.Scanner;
public class ConsoleInput {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter your name: ");
String name = scanner.nextLine();
System.out.println("Hello, " + name + "!");
scanner.close();
}
}
2. Reading from Files:
- Java's `FileInputStream`, `BufferedReader`, or `Scanner` can be used to read data from files.
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
public class FileInput {
public static void main(String[] args) {
try (BufferedReader reader = new BufferedReader(new FileReader("example.txt"))) {
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output in Java:
1. Writing to Console:
- The `System.out.println()` method is commonly used for console output.
public class ConsoleOutput {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
2. Writing to Files:
- Java's `FileOutputStream`, `BufferedWriter`, or `PrintWriter` can be used to write data to files.
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
public class FileOutput {
public static void main(String[] args) {
try (BufferedWriter writer = new BufferedWriter(new FileWriter("output.txt"))) {
writer.write("Writing to a file in Java.");
} catch (IOException e) {
e.printStackTrace();
}
}
}
3. Standard Output and Error Streams:
- The `System.out` and `System.err` streams are used for standard output and error.
public class StandardOutputError {
public static void main(String[] args) {
System.out.println("This is standard output.");
System.err.println("This is standard error.");
}
}
These examples cover basic input and output operations in Java. The `java.util.Scanner` class is versatile for handling various types of input, and the `java.io` package provides a range of classes for file-based input and output operations. Understanding these concepts is fundamental for building interactive and data-driven Java applications.
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