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(); ...
Exceptions:
Exceptions represent exceptional conditions that can occur during the execution of a program. They can be caused by various factors such as invalid input, network issues, or file not found. Exceptions are further categorized into two types:
1. Checked Exceptions: These are exceptions that are checked at compile time. They are typically recoverable and should be handled by the programmer. Examples include `IOException`, `SQLException`, etc.
2. Unchecked Exceptions (Runtime Exceptions): These are exceptions that are not checked at compile time. They usually indicate programming errors or unexpected conditions. Examples include `NullPointerException`, `ArrayIndexOutOfBoundsException`, etc.
Errors:
Errors, on the other hand, represent serious problems that are typically beyond the control of the program. They are usually caused by system-level issues or conditions such as out of memory, stack overflow, or hardware failures. Errors are not normally caught or handled by the program because they indicate critical issues that may lead to program termination.
Handling Exceptions and Errors:
Exceptions are handled using `try`, `catch`, and `finally` blocks. The `try` block contains the code that may throw an exception, the `catch` block catches and handles the exception, and the `finally` block is used for cleanup code that should be executed whether an exception occurs or not.
Errors, on the other hand, are usually not caught or handled by the program. They indicate serious problems that may require intervention at the system level.
Example:
public class ExceptionHandlingExample {
public static void main(String[] args) {
try {
// Code that may throw an exception
int result = 10 / 0; // ArithmeticException
} catch (ArithmeticException e) {
// Handling the exception
System.out.println("Division by zero!");
} finally {
// Cleanup code (optional)
System.out.println("Finally block executed.");
}
}
}
In this example, the program attempts to perform division by zero, which results in an `ArithmeticException`. The exception is caught and handled in the `catch` block, and the `finally` block is executed regardless of whether an exception occurs or not.
Analogy:
Imagine you are driving a car (running a program). Exceptions are like unexpected roadblocks or detours that you encounter along the way. You can anticipate and handle these roadblocks by taking alternate routes (exception handling). Errors, on the other hand, are like sudden mechanical failures or road collapses that require immediate attention from a mechanic (system-level intervention) to fix. You, as the driver (programmer), may not have control over these critical issues and may need external assistance.
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