1. Catch Specific Exceptions
Always catch the most specific exception first. This helps in identifying the exact issue and handling it appropriately.
try { // Code that may throw an exception } catch (FileNotFoundException e) { // Handle FileNotFoundException } catch (IOException e) { // Handle other IOExceptions }
2. Avoid Empty Catch Blocks
Empty catch blocks can hide errors and make debugging difficult. Always log the exception or take some action.
try { // Code that may throw an exception } catch (IOException e) { e.printStackTrace(); // Log the exception }
3. Use Finally Block for Cleanup
The finally block is used to execute important code such as closing resources, regardless of whether an exception is thrown or not.
BufferedReader reader = null; try { reader = new BufferedReader(new FileReader("file.txt")); // Read file } catch (IOException e) { e.printStackTrace(); } finally { if (reader != null) { try { reader.close(); } catch (IOException e) { e.printStackTrace(); } } }
4. Don’t Catch Throwable
Avoid catching Throwable as it includes errors that are not meant to be caught, such as OutOfMemoryError.
try { // Code that may throw an exception } catch (Exception e) { e.printStackTrace(); // Catch only exceptions }
5. Log Exceptions Properly
Use a logging framework like Log4j or SLF4J to log exceptions instead of using System.out.println.
private static final Logger logger = LoggerFactory.getLogger(MyClass.class); try { // Code that may throw an exception } catch (IOException e) { logger.error("An error occurred", e); }
6. Rethrow Exceptions if Necessary
Sometimes, it’s better to rethrow the exception after logging it or performing some action.
try { // Code that may throw an exception } catch (IOException e) { logger.error("An error occurred", e); throw e; // Rethrow the exception }
7. Use Multi-Catch Blocks
In Java 7 and later, you can catch multiple exceptions in a single catch block.
try { // Code that may throw an exception } catch (IOException | SQLException e) { e.printStackTrace(); // Handle both IOException and SQLException }
8. Avoid Overusing Exceptions for Control Flow
Exceptions should not be used for regular control flow. They are meant for exceptional conditions.
// Avoid this try { int value = Integer.parseInt("abc"); } catch (NumberFormatException e) { // Handle exception } // Prefer this if (isNumeric("abc")) { int value = Integer.parseInt("abc"); }
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