When Are Resources Released: Before or After the Finally Block in Java?

Are resources, such as streams or connections, closed before or after the finally block is executed in Java?

try (BufferedReader reader = new BufferedReader(new FileReader("file.txt"))) {
    // Read and process the file
} catch (IOException e) {
    e.printStackTrace();
} // No need for finally, resources are managed automatically.

In Java, resources managed by try-with-resources are closed after the execution of the try block and before entering the finally block. This ensures that resources are released even when exceptions occur, providing a clean and efficient method for resource management.

// Example of try-with-resources
try (PrintWriter out = new PrintWriter("output.txt")) {
    out.println("Hello, world!");
} catch (FileNotFoundException e) {
    e.printStackTrace();
} // out is automatically closed after this block.

Causes

• The try-finally construct allows you to guarantee that some code will execute regardless of whether an exception is thrown in the try block.
• The closure of resources occurs just before the finally block to ensure any necessary cleanup without leaving resources open.

Solutions

• Utilize try-with-resources statement for automatic resource management, which simplifies code and eliminates boilerplate for freeing resources.
• Always implement resource cleanup in the finally block if not using try-with-resources, ensuring that resources like streams, files, and network connections are closed properly.

Mistake: Forgetting to close resources manually in the finally block when not using try-with-resources.

Solution: Always wrap resource management in a try-with-resources statement whenever applicable.

Mistake: Assuming resources are still available in the finally block after being closed in the try block.

Solution: Understand that resources used in try-with-resources are closed immediately after exiting the try block.