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Students will gain the skills to handle errors and exceptional situations in their Java programs. They will learn about different types of exceptions and how to use try-catch blocks effectively.
By the end of this unit, students will be able to write robust Java applications that can gracefully handle and recover from various error conditions.
Each lesson in this unit follows the same structure:
- Read the concept
- Study the example
- Write or modify Java code
- Compile the program
- Run the code
- Review the output
- Complete a hands-on lab
- Answer review questions
Types of exceptions
An exception is an event that disrupts the normal flow of a program. Java exceptions are organized in a class hierarchy rooted at the Throwable class. Errors represent serious problems that a program typically cannot recover from. Exceptions represent conditions that a program can catch and handle. Students will learn the difference between checked exceptions, which the compiler requires to be handled, and unchecked exceptions, which occur at runtime due to programming errors.
Try-catch blocks
A try block contains code that might throw an exception. A catch block handles a specific type of exception if it is thrown inside the try block. Students will practice wrapping risky code in try-catch blocks and writing appropriate responses to different exception types.
Multiple catch blocks and exception hierarchies
A single try block can have multiple catch blocks, each handling a different type of exception. When writing multiple catch blocks, more specific exception types must be caught before more general ones. Students will practice designing exception handling logic that responds appropriately to different failure scenarios.
Throws clause and custom exceptions
A method can declare that it may throw a checked exception using the throws keyword in its signature. This informs the caller that it must either handle the exception or declare it as well. Students will also learn to create custom exception classes by extending Exception or RuntimeException, allowing them to represent application-specific error conditions.
Finally block and resource management
A finally block runs after the try and catch blocks regardless of whether an exception was thrown. It is typically used to release resources such as file handles or database connections. Students will also learn about the try-with-resources statement, which automatically closes resources that implement the AutoCloseable interface.
This unit is introduced at College / University — Year 2 and is included in the Year 3 track as well.
| Academic Level | Track |
|---|---|
| College / University — Year 2 | Units 1–11 |
| College / University — Year 3 | Units 1–13 |
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