Exception Handling Keywords in Java

📌 What is an Exception?

An exception is an unwanted or unexpected event that occurs during the execution of a program and disrupts its normal flow.

🔍 Common Examples:
Dividing a number by zero
Accessing a null object
Trying to open a file that doesn’t exist

1. try Block

The try block is used to wrap code that might throw an exception.

 Syntax:
try {
    // risky code
}
 Example:
try {
    int a = 10 / 0; // Exception occurs
}

Where is it used?
Database operations
File handling
Network calls

1. catch Block

The catch block handles the exception thrown inside the try block.

Syntax:
catch(Exception e) {
    // handling code
}
 Example:
try {
    int a = 10 / 0;
} catch (ArithmeticException e) {
    System.out.println("Cannot divide by zero");
}

Where is it used?
Displaying user-friendly error messages
Preventing program crashes

1. finally Block

The finally block always executes, whether an exception occurs or not.

 Syntax:
finally {
    // cleanup code
}
 Example:
try {
    int a = 10 / 2;
} catch (Exception e) {
    System.out.println("Error");
} finally {
    System.out.println("Always executed");
}

Real-Time Usage:
Closing database connections
Closing files
Releasing system resources

1. throw Keyword

The throw keyword is used to manually throw an exception.

Syntax:
throw new Exception("message");
 Example:
public class Main {
    public static void main(String[] args) {
        int num = -5;

        if (num < 0) {
            throw new ArithmeticException("Negative number not allowed");
        }

        System.out.println("Valid number");
    }
}

Where is it used?
Custom validations
Business rules (e.g., age restrictions)

1. throws Keyword

The throws keyword is used in method signatures to declare exceptions.

Syntax:
void method() throws Exception {
    // code
}
 Example:
import java.io.*;

class Test {
    void readFile() throws IOException {
        FileReader file = new FileReader("test.txt");
    }
}

Where is it used?
File handling
Checked exceptions
Passing responsibility to the caller

** Conclusion**

Exception handling in Java helps you build robust and error-free applications. By using try, catch, finally, throw, and throws, you can manage errors effectively and ensure smooth program execution.