Programming Chapter 5: Exception Handling

Chapter 5: Exception Handling

• Exception handling is a crucial mechanism in programming for managing abnormal events or errors that may occur during program execution.
• Errors in a program are called bugs, and removing these errors is called debugging.
• Errors are categorized into compile-time errors and runtime errors.
• Compile-time errors are syntax or format errors identified by the compiler. These errors prevent the creation of the executable class file.
• Runtime errors (also known as exceptions) are errors that indicate problems during program execution. These errors can be due to insufficient memory, operations like division by zero, or array index out of bounds.
• Abnormal events in a program are called exceptions.
• Exceptions can occur at compile time or runtime.
• Exceptions occurring at compile time are called checked exceptions.
• Exceptions occurring at runtime are called unchecked exceptions.
• The base class for all exceptions is Throwable.
• Throwable has two immediate subclasses: Exception and Error.
• Exception represents exceptional conditions that programs should handle.
• Error represents errors within the runtime environment.
• RuntimeException is a subclass of Exception and is commonly used for errors that can potentially be prevented by careful programming.
• User-defined exceptions are exceptions that are created to handle application-specific issues.

Exception Hierarchy

• All exceptions in Java are subclasses of the Throwable class.
• Throwable has two immediate child classes: Exception and Error.
• Exception represents error conditions that a program should catch and handle.
• Error represents serious problems within the runtime environment.
• Common exceptions include ArithmeticException, ArrayIndexOutOfBoundsException, NullPointerException, FileNotFoundException, and others.

Exception Handling

• Exception handling in Java utilizes the try, catch, and finally blocks.
• The try block encloses the code that might throw an exception.
• The catch block encloses the code that handles an exception.
• The finally block ensures that code executes regardless of whether an exception was thrown or not.

Checked Exceptions

• Checked exceptions are exceptions that the compiler requires you to handle (either catch or declare).
• Compilation fails if the programmer does not handle or declare checked exceptions.
• Examples of checked exceptions include, but not limited to: ClassNotFoundException, NoSuchMethodException, IOException, SQLException.

Unchecked Exceptions

• Unchecked exceptions are those exceptions that the compiler doesn't require you to handle. The program might terminate unexpectedly if an unchecked exception occurs.
• Examples of unchecked exceptions include ArithmeticException, NullPointerException, ArrayIndexOutOfBoundsException, NumberFormatException.

Throwing Exceptions

• The throw keyword is used to explicitly throw an exception.
• Custom exceptions extend the Exception class.

throws Declaration

• The throws keyword in a method declaration specifies the type of exceptions that the method might throw.
• The throws clause is part of the method signature.
• throws is used to instruct the calling method to handle those exceptions.

finally Clause

• The finally block ensures that code always executes, regardless of whether an exception occurs.
• It is frequently used to release resources (e.g., closing files).
• finally is essential when dealing with I/O resources or other potentially critical operations.

Creating Custom Exceptions

• Custom exception classes extend the built-in Exception class.
• Custom exceptions are useful to handle application-specific errors.
• Create a new class for custom exceptions.
• Extend Exception, the exception class.

Explore the essential concepts of exception handling in programming through this quiz. Learn about compile-time and runtime errors, the debugging process, and the distinction between checked and unchecked exceptions. Test your understanding of how exceptions can affect program execution and how they're managed.