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

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

Introduction:
In the software development process, data objects are very important. In order to ensure data security and consistency, data objects usually need to be designed to be immutable. In Java, we can use Records class to create immutable data objects. This article will introduce how to use the Records class to create immutable data objects in Java 14 and provide corresponding code examples.

1. What is the Records class?
   The Records class is a new feature in Java 14 that provides a cleaner and simpler way to create immutable data objects. The Records class automatically generates several methods, including the construction method, equals method, hashCode method and toString method. The implementations of these methods are automatically generated based on the properties of the class, so we do not need to manually write these tedious codes.
2. How to define a Records class?
   Defining the Records class is very simple, just use the keyword record plus the class name and attributes. For example, the following is an example of a simple Person class:

record Person(String name, int age) {}

The above code defines a Records class named Person, which has two attributes, name and age. The Records class is immutable, so we cannot modify the objects after they are created.

3. How to use Records class?
   It is very convenient to use the Records class. You can create objects, access properties and call methods just like using ordinary classes. For example, we can create a Person object like this:

Person person = new Person("Alice", 25);

We can also access the properties of the Records class like the properties of a normal class:

String name = person.name();
int age = person.age();

It is worth noting that the Records class A toString() method is automatically generated, so we can directly call the toString() method to obtain the string representation of the object:

System.out.println(person);  // 输出：Person[name=Alice, age=25]

4. Records class Advantages
   Using the Records class has the following advantages:

4.1 Simplicity: Compared with the traditional class definition method, the Records class is more concise, eliminating the need for tedious code writing.

4.2 Immutability: The properties in the Records class are final and cannot be modified after they are created, ensuring the immutability of the data object.

4.3 Automatically generated methods: The Records class automatically generates some commonly used methods for us, such as equals, hashCode and toString, etc. We do not need to write these methods manually.

4.4 Easy to read and write: The Records class is clearly defined, and the properties can be obtained through simple access methods, making the code easy to understand and maintain.

5. Restrictions of the Records class
   However, the Records class also has some restrictions:

5.1 Properties must be final: Properties in the Records class must be declared final , which is to ensure the immutability of data objects.

5.2 The constructor cannot be explicitly defined: The constructor of the Records class is implicitly generated, so we cannot explicitly define the constructor.

5.3 Cannot inherit other classes: The Records class cannot inherit other classes, but it can implement interfaces.

5.4 Access modifiers cannot be used on properties: Properties in the Records class are public by default, and other access modifiers cannot be used.

6. Summary
   In Java 14, the Records class provides a more concise and convenient way for us to create immutable data objects. We only need to define the Records class using the record keyword and declare the properties, and the rest of the work is automatically generated by the Records class. Using the Records class can improve the readability and maintainability of your code. However, we also need to pay attention to some restrictions of the Records class, such as properties must be final, constructors cannot be explicitly defined, etc. I hope this article can help you understand and use the Records class in Java 14.

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