Java Best Practices (17+)
Code Style
| Rule | Guideline |
|---|---|
| Formatter | google-java-format |
| Analysis | SpotBugs, Error Prone |
| Naming | Clear, no abbreviations |
Modern Features
| Feature | Usage |
|---|---|
| Records | Immutable data carriers |
| Sealed classes | Restricted hierarchies |
| Pattern matching | instanceof with binding |
var | Local type inference |
java
public record User(String id, String name) {}
if (obj instanceof String s && !s.isEmpty()) { process(s); }
public sealed interface Result<T> permits Success, Failure {}
record Success<T>(T value) implements Result<T> {}
record Failure<T>(Exception error) implements Result<T> {}
Error Handling
| Rule | Guideline |
|---|---|
| Specific exceptions | Not bare Exception |
| Try-with-resources | For AutoCloseable |
java
try (var reader = new BufferedReader(new FileReader(path))) {
return reader.lines().toList();
} catch (IOException e) {
throw new ConfigException("Failed: " + path, e);
}
Project Structure
code
src/main/java/com/example/{domain,service}/
src/test/java/
pom.xml or build.gradle
Common Patterns
| Pattern | Usage |
|---|---|
| Optional | Null-safe returns |
| Stream API | Functional collections |
| Builder | Complex construction |
java
public Optional<User> findById(String id) {
return Optional.ofNullable(users.get(id));
}
Anti-Patterns
| Avoid | Use Instead |
|---|---|
| Returning null | Optional<T> |
| Mutable data | Records |
instanceof chains | Pattern matching |
Testing (JUnit 5 + AssertJ)
java
@Test void shouldProcess() {
var service = new Service(mockRepo);
var result = service.process(input);
assertThat(result.status()).isEqualTo(SUCCESS);
}