# Use Java Records
# Description
Since Java 16, record classes are a new kind of class in the Java language. Record classes help to model plain data aggregates with less ceremony than normal classes. This rule replaces the declarations of:
- local classes
- inner classes
- package private root classes
with record class declarations. Thus dropping some boilerplate code, guaranteeing immutability in language level, and providing better compatibility with the new or upcoming features, e.g., Pattern Matching.
Requirements
- Java 16
# Benefits
Guarantees immutability. Eliminates boilerplate code. Encourages better serialization. Boosts compatibility with upcoming features.
# Tags
# Code Changes
# Local Classes
Pre
void plainGeometry() {
// ...
class Point {
private final int x;
private final int y;
Point(int x, int y) {
this.x = x;
this.y = y;
}
public int x() {
return x;
}
public int y() {
return y;
}
}
// ...
}
Post
void plainGeometry() {
// ...
record Point(int x, int y) {}
//...
}
# Nested Classes
Pre
public class PlainGeometry {
// ...
private static final class Point {
private final int x;
private final int y;
Point(int x, int y) {
this.x = x;
this.y = y;
}
public int x() {
return x;
}
public int y() {
return y;
}
}
// ...
}
Post
public class PlainGeometry {
//...
private record Point(int x, int y) {}
//...
}
# Multiple Constructors
Pre
// ...
private static final class Point {
private final int x;
private final int y;
Point(int x, int y) {
this.x = x;
this.y = y;
}
Point() {
this(0,0);
}
public int x() {
return x;
}
public int y() {
return y;
}
}
// ...
Post
//...
private record Point(int x, int y) {
Point() {
this(0,0);
}
}
//...
# Parameterized Inner Classes
Pre
//...
private static final class GenericWrapper<T> {
private final T value;
public GenericWrapper(T value) {
this.value = value;
}
public T value() {
return value;
}
}
//...
Post
//...
private record GenericWrapper<T> (T value) {}
//...
# Additional Methods
Pre
// ...
private static final class Person {
private final String firstName;
private final String lastName;
Person(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
public String firstName() {
return firstName;
}
public String lastName() {
return lastName;
}
public String name() {
return firstName + " " + lastName;
}
}
// ...
Post
//...
private record Person(String firstName, String lastName) {
public String name() {
return firstName + " " + lastName;
}
}
//...
Use a Java Refactoring Tool
No license required
You can review this refactoring on your code without a license by installing jSparrow to your Eclipse IDE. Install the plug-in from Eclipse IDE: Eclipse Marketplace.
System-wide Refactoring
Do you want to automate this refactoring (and many more) to your system-wide code? The automatic application of this system-wide refactoring can be unlocked by acquiring your jSparrow license.
