How to use Records class in Java 14 to create mutable and immutable data objects

How to use Records class to create mutable and immutable data objects in Java 14

Introduction:
Before Java 14, we usually used classes to create data objects, defining fields in them , generate getter and setter methods. Such code is lengthy and cumbersome and requires a lot of boilerplate code. Java 14 introduced the Records class, which provides a cleaner way to create data objects. The Records class can automatically generate fields, constructors, getters, equals, hashCode and other methods. This article will introduce how to use the Records class in Java 14 to create mutable and immutable data objects, and give corresponding code examples.

Variable data objects:
In Java, we can use the keyword "record" to create a Record class. This class automatically generates fields and many methods. We can use the var keyword to define and initialize a mutable data object.

The following is an example showing how to create a mutable Person object:

record Person(String name, int age) {}

This Person class has two fields: name and age. We can use this class using the following code:

var person = new Person("John", 30);
person.setName("Mike");
person.setAge(35);

In this example, we create a mutable object named person and set its name and age fields. We can also use the generated setName and setAge methods to modify the field values ​​​​of this object.

Immutable data object:
To create an immutable data object, we only need to mark the fields of the Record class as final. This way, these fields cannot be modified. We can use the following code example:

record Person(String name, int age) {
    public Person {
        if(age < 0) {
            throw new IllegalArgumentException("Age cannot be negative");
        }
    }
}

In this example, we have added a constructor to the Person class. We use the constructor to verify the value of the age field. If age is less than 0, an exception will be thrown.

This immutable Person object can be created and used using the following code:

var person = new Person("John", 30);
System.out.println(person.name());
System.out.println(person.age());

In this example, we create an immutable object named person and pass it by calling name and age method to get the value of the field. Since the age field is final, it cannot be modified.

Summary:
In this article, we introduced how to use the Records class in Java 14 to create mutable and immutable data objects. We show how to create mutable and immutable Person objects, with corresponding code examples. The Records class provides a concise way to create data objects, reducing verbose and repetitive code. It is a very useful new feature in Java 14 that can improve development efficiency and code quality. You can try to use the Records class to create data objects in your own projects and experience its convenience.

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