Java Code Simplification Techniques and Best Practices

This article presents a systematic collection of refactoring techniques for Java code, aiming to make programs shorter, clearer, and more maintainable while preserving functionality and performance.

It starts with simplifying conditional statements by replacing verbose if‑else blocks with ternary operators and direct boolean returns, e.g. String title = isMember(phone) ? "会员" : "游客"; and

return Objects.nonNull(user) && Boolean.TRUE.equals(user.getIsSuper());

. Null‑handling is streamlined using Optional, for example

Integer thisValue = Optional.ofNullable(value).orElse(DEFAULT_VALUE);

or

Integer thisValue = Optional.ofNullable(value).filter(v -> v.compareTo(MAX_VALUE) <= 0).orElse(MAX_VALUE);

.

Collection processing is refactored from manual loops to the Stream API. Matching, filtering, mapping and grouping become one‑liner expressions such as:

boolean isFound = userList.stream().anyMatch(u -> Objects.equals(u.getId(), userId));

,

List<UserVO> userVOList = userDOList.stream().map(this::transUser).collect(Collectors.toList());

, and

Map<Long, List<UserDO>> roleUserMap = userDOList.stream().collect(Collectors.groupingBy(UserDO::getRoleId));

. Method references further reduce boilerplate: list.sort(String::compareToIgnoreCase);.

Language features are leveraged to cut boilerplate code: static imports replace fully‑qualified constants, try‑with‑resources removes explicit finally blocks, unchecked exceptions avoid unnecessary throws declarations, and Lombok annotations ( @Getter, @Setter, @AllArgsConstructor, etc.) eliminate repetitive getters, setters and constructors.

Generics replace raw Object usage, providing type safety and concise signatures. Examples include a generic interface public interface Comparable<T> { int compareTo(T other); }, a generic class

public class Point<T extends Number> { private T x; private T y; }

, and a generic method

public static <K,V> Map<K,V> newHashMap(K[] keys, V[] values) { ... }

.

Utility methods from libraries (e.g., CollectionUtils.isNotEmpty, StringUtils, Guava ImmutableList) replace manual checks and collection creation, while functional helpers such as Math.max simplify conditional assignments.

Design patterns are applied to structure code: a template method abstract class encapsulates common Redis value handling; a builder‑style method uses Function and Predicate instead of a custom interface for data parsing and storage; and AOP proxy techniques replace repetitive try‑catch blocks with a global @ControllerAdvice or AspectJ advice for exception handling.

Finally, the article advises removing redundant modifiers ( public in interfaces, final on methods of final classes), unused variables, dead code, and unnecessary private constructors, thereby achieving a leaner code base.