Java Exceptions

The exceptions in Java are a mechanism for handling runtime errors and abnormal conditions that can occur during the execution of a program. Exceptions provide a way to gracefully handle errors and failures, making your code more robust and maintainable. Java divides exceptions into two main categories: checked exceptions and unchecked exceptions.

1. Checked Exceptions:

• Checked exceptions are exceptions that the compiler requires you to handle or declare using the throws keyword in the method signature.
• These exceptions are typically related to situations where the program can reasonably anticipate and recover from the error.
• Examples of checked exceptions include IOException, SQLException, and ClassNotFoundException.

1. Unchecked Exceptions:

• Unchecked exceptions (also known as runtime exceptions) are exceptions that the compiler does not force you to handle or declare.
• These exceptions usually result from programming errors like invalid array indices, null references, or improper type casting.
• Examples of unchecked exceptions include NullPointerException, ArrayIndexOutOfBoundsException, and IllegalArgumentException.

Here’s a basic overview of how exceptions are used in Java:

• Throwing Exceptions:
  Use the throw keyword to explicitly throw an exception when an exceptional situation occurs within a method.

  if (condition) {
      throw new SomeException("This is an exceptional situation");
  }

• Catching Exceptions:
  Use the try–catch block to catch exceptions and handle them gracefully. The catch block contains code that’s executed when an exception of the specified type occurs.

  try {
      // Code that may throw an exception
  } catch (SomeException ex) {
      // Handle the exception
  }

• Finally Block:
  You can use the finally block to provide code that executes regardless of whether an exception was thrown. This block is often used for cleanup operations.

  try {
      // Code that may throw an exception
  } catch (SomeException ex) {
      // Handle the exception
  } finally {
      // Cleanup or finalization code
  }

• Declaring Exceptions:
  When a method can throw checked exceptions, you need to declare them using the throws keyword in the method signature.

  public void readFile(String filename) throws IOException {
      // Code to read a file
  }

• Creating Custom Exceptions:
  You can create your own custom exception classes by extending existing exception classes or implementing the Throwable interface.

  public class CustomException extends Exception {
      // Custom exception code
  }

By effectively using exceptions in your Java code, you can enhance the robustness and maintainability of your programs, making them better equipped to handle various error scenarios.