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🏷 Exception Handling 5 patterns

Topic: Exception Handling

All Java patterns related to Exception Handling — java.evolved

Try-with-resources improvement

Old Connection conn = getConnection(); // Must re-declare in try try (Connection c = conn) { use(c); }

Modern Connection conn = getConnection(); // Use existing variable directly try (conn) { use(conn); }

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JDK 9+ learn more →

Helpful NullPointerExceptions

Old // Old NPE message: // "NullPointerException" // at MyApp.main(MyApp.java:42) // Which variable was null?!

Modern // Modern NPE message: // Cannot invoke "String.length()" // because "user.address().city()" // is null // Exact variable identified!

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JDK 14+ learn more →

Multi-catch exception handling

Old try { process(); } catch (IOException e) { log(e); } catch (SQLException e) { log(e); } catch (ParseException e) { log(e); }

Modern try { process(); } catch (IOException | SQLException | ParseException e) { log(e); }

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JDK 7+ learn more →

Optional.orElseThrow() without supplier

Old // Risky: get() throws if empty, no clear intent String value = optional.get(); // Verbose: supplier just for NoSuchElementException String value = optional .orElseThrow(NoSuchElementException::new);

Modern // Clear intent: throws NoSuchElementException if empty String value = optional.orElseThrow();

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JDK 10+ learn more →

Class.newInstance() to constructor reflection

Old Plugin plugin = pluginClass.newInstance();

Modern Plugin plugin = pluginClass .getDeclaredConstructor() .newInstance();

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JDK 9+ learn more →