Java Record - No more boilerplate codes, in the Java way
3 min readJava introduced the record keyword in JDK 14, simplifying how developers handle immutable data. This feature reduces the need to write boilerplate code in data carrier classes. This feature is commonly believed not just a mere addition, but more of a paradigm shift in how we handle immutable data in Java.
Why Java Records Are Useful
Before Records, Java developers spent a lot of time writing data carrier classes. This meant creating constructors, getters, and methods like equals(), hashCode(), and toString(). It was repetitive and prone to errors. Development tools have streamlined the process, but not making it less verbose. Third-party libraries have tried to address this issue, and now the JDK provides its own solution.
Practical Use Cases
Records are ideal for managing read-only data. For example, in an application handling financial transactions, details like amount, date, and account number can be efficiently encapsulated using records. This is because once recorded, these details don't change. Records are also useful in APIs as Data Transfer Objects (DTOs), making them lightweight and focused on transferring data.
Creating a record is straightforward: use the record keyword, followed by the record's name and its components. The components can be any type, including primitives, other records, and arrays.
Records automatically generate essential methods like constructors, getters, equals(), hashCode(), and toString(). This automation means developers don't have to manually write these methods, saving time and reducing errors.
public record User(String name, String email) {}A record automatically includes:
- A private final field for each component
- A public getter method for each component, maintaining the component's name and type; for example, User::name() and User::email()
- A public constructor, which is shaped by the list of record components. This constructor assigns each private field with its matching argument.
- A
equals()andhashCode()methods are provided, establishing that two records are identical if they share the same type and all their components match. - A
toString()method that presents the record's components, including their names, in its string representation.
Comparing with regular class
Records in Java introduce a concise way to model immutable data, though they come with certain limitations. Despite these constraints, they maintain the versatility of regular classes, offering a wide range of functionalities.
Let's looks at it on both sides:
Record class can do
- Records can be declared within another class and are inherently static if nested.
- They can be generic.
- Records can implement interfaces.
- Use the new keyword to instantiate records.
- Within a record, you can declare static methods, static fields, static initializers, constructors, instance methods, and nested types.
- Records and their components can be annotated.
Record class cannot do
- Records can't extend other classes.
- Records can't have instance fields except for the private final fields that match the record's components. Any other fields must be static.
- Records are inherently final and cannot be abstract.
- Record components are automatically final.
Summary
In summary, the Java Record classes mark a substantial advancement in data management within Java, simplifying coding practices, minimizing mistakes, and enhancing clarity. More than just reducing the amount of code, Records facilitate smarter, easier to maintain, and more effective Java programming. For developers deeply involved in the Java landscape, adopting Records represents a crucial step towards achieving more refined and stable codebases.
