Java 15 Records vs. Lombok

This article shows how to use the new records feature introduced in java15 and compares it with lombok.

Let’s start with a simple immutable class which holds a couple of private fields.

Lombok way

Add lombok annotations on top of the class:

import lombok.AllArgsConstructor;
import lombok.Getter;

@AllArgsConstructor
@Getter
public class TransactionLombok {
    private final String from;
    private final String to;
    private final int amount;
}

A constructor with all arguments and getters are generated by lombok.

TransactionLombok transactionLombok = new TransactionLombok("you", "me", 100);
assertThat(transactionLombok.getFrom()).isEqualTo("you");
assertThat(transactionLombok.getTo()).isEqualTo("me");
assertThat(transactionLombok.getAmount()).isEqualTo(100);

Records way

Define a record:

record TransactionRecord(String from, String to, int amount) {
}

You get constructor and getters by default in a record:

TransactionRecord transactionRecord = new TransactionRecord("you", "me", 100);
assertThat(transactionRecord.from()).isEqualTo("you");
assertThat(transactionRecord.to()).isEqualTo("me");
assertThat(transactionRecord.amount()).isEqualTo(100);

As we can see the new record keyword does the same job in a much neater way.

Anything more?

Yes, records can do more than that. It also provides the equals, hashCode and toString automatically for you. So this works as well.

assertThat(transactionRecord.equals(anotherTransactionRecord)).isTrue();
assertThat(transactionRecord.hashCode()).isEqualTo(anotherTransactionRecord.hashCode());
assertThat(transactionRecord.toString()).isEqualTo("TransactionRecord[from=you, to=me, amount=100]");

While in lombok you have to achieve the same thing by adding a few more annotations like this:

@ToString
@EqualsAndHashCode
@AllArgsConstructor
@Getter
public class TransactionLombok {

Or just make it a value:

@Value
public class TransactionLombok {

So the record keyword can be considered as an equivalent to lombok’s @Value annotation.

Customized constructor

In addition, records also supports customized constructors like this:

public TransactionRecord(String from, String to) {
    this(from, to, 0);
}

And if you want to validate the arguments, it’s also possible:

public TransactionRecord {
    Objects.requireNonNull(from);
    Objects.requireNonNull(to);
}

Can records replace lombok?

No.

Even though records provides a lot of nice features and is neat in code, lombok still has way more features than records. For example:

@Data
public class TransactionLombok {

Records can’t provide mutable object but lombok can with @Data. Therefore lombok will most probably coexist with records for long time.

PS: You can find all the code samples here.