Types of Exceptions

In Java, exceptions are categorized into two main types: checked exceptions and unchecked exceptions.

Checked Exceptions

Checked exceptions are exceptions that must be declared in a method's signature or handled within the method using a try-catch block. These exceptions are typically expected and can be reasonably handled by the calling code.

Some common checked exceptions in Java include:

• FileNotFoundException: Thrown when a file is not found.
• IOException: Thrown when an I/O error occurs.
• SQLException: Thrown when a database access error occurs.

Here's an example that demonstrates how to handle a checked exception:

1import java.io.FileInputStream;
2import java.io.FileNotFoundException;
3
4public class Main {
5    public static void main(String[] args) {
6        try {
7            FileInputStream file = new FileInputStream("example.txt");
8            // Process the file
9        } catch (FileNotFoundException e) {
10            System.out.println("File not found!");
11        }
12    }
13}

Unchecked Exceptions

Unchecked exceptions are exceptions that do not need to be declared in a method's signature or handled explicitly. These exceptions typically represent programming errors or unexpected conditions that cannot be recovered from.

Some common unchecked exceptions in Java include:

• NullPointerException: Thrown when a null reference is accessed.
• IndexOutOfBoundsException: Thrown when an index is out of range.
• ArithmeticException: Thrown when an arithmetic operation results in an illegal or undefined value.

Here's an example that demonstrates an unchecked exception:

1public class Main {
2    public static void main(String[] args) {
3        int[] numbers = {1, 2, 3};
4        int result = numbers[4]; // Throws ArrayIndexOutOfBoundsException
5        // Rest of the code
6    }
7}