{"generator":"Jekyll","link":[{"@attributes":{"href":"https:\/\/www.devdiaries.net\/feed.xml","rel":"self","type":"application\/atom+xml"}},{"@attributes":{"href":"https:\/\/www.devdiaries.net\/","rel":"alternate","type":"text\/html"}}],"updated":"2021-03-09T20:51:34+00:00","id":"https:\/\/www.devdiaries.net\/feed.xml","title":"Devdiaries","subtitle":"Programming tips, tricks, news for the Java programming language, Openhift, Cloud Native Microservices and Security","entry":[{"title":"Anemic Domain Model vs Rich Domain Model in Java","link":{"@attributes":{"href":"https:\/\/www.devdiaries.net\/blog\/Java-Anemic-Domain-Model-Rich-Domain-Model\/","rel":"alternate","type":"text\/html","title":"Anemic Domain Model vs Rich Domain Model in Java"}},"published":"2021-03-08T00:00:00+00:00","updated":"2021-03-08T00:00:00+00:00","id":"https:\/\/www.devdiaries.net\/blog\/Java-Anemic-Domain-Model-Rich-Domain-Model","content":"

When we write code, we try to hide as many details as possible - using appropriate access modifiers. Most often we use getters and setters methods to set the appropriate state of an object. Is this a good practice?\nIn this article you will learn what is Anemic Domain Model<\/strong> and Rich Domain Model<\/strong> and which way of creating models is the best. \nWhat\u2019s more, you\u2019ll find a special opportunity from CodeGym<\/a> at the end of this post. I invite you to read :)<\/p>\n

Why are getters and setters unsafe? Anemic Domain Model vs Rich Domain Model<\/h1>\n\n

Take a look at the code below:<\/p>\n\n

import<\/span> java.util.UUID<\/span>;<\/span>  \n  \npublic<\/span> class<\/span> User<\/span> {<\/span>  \n public<\/span> UUID<\/span> userId<\/span>;<\/span>  \n public<\/span> String<\/span> name<\/span>;<\/span>  \n public<\/span> String<\/span> email<\/span>;<\/span>  \n public<\/span> boolean<\/span> isBlocked<\/span>;<\/span>   \n public<\/span> boolean<\/span> isActive<\/span>;<\/span>\n}<\/span><\/code><\/pre><\/figure>\n\n
Do you see any potential risks? That\u2019s right! The class contains public fields that can be changed anywhere else in the application code.\nIt will be hard for us to control such an application, especially if it becomes a big project.<\/p>\n\n
All right. Let\u2019s make changes so that the fields are not public:<\/p>\n\n
import<\/span> java.util.UUID<\/span>;<\/span>\n\npublic<\/span> class<\/span> User<\/span> {<\/span>\n    private<\/span> UUID<\/span> userId<\/span>;<\/span>\n    private<\/span> String<\/span> name<\/span>;<\/span>\n    private<\/span> String<\/span> email<\/span>;<\/span>\n    private<\/span> boolean<\/span> isBlocked<\/span>;<\/span>\n    private<\/span> boolean<\/span> isActive<\/span>;<\/span>\n\n    public<\/span> UUID<\/span> getUserId<\/span>()<\/span> {<\/span>\n        return<\/span> userId<\/span>;<\/span>\n    }<\/span>\n\n    public<\/span> void<\/span> setUserId<\/span>(<\/span>UUID<\/span> userId<\/span>)<\/span> {<\/span>\n        this<\/span>.<\/span>userId<\/span> =<\/span> userId<\/span>;<\/span>\n    }<\/span>\n\n    public<\/span> String<\/span> getName<\/span>()<\/span> {<\/span>\n        return<\/span> name<\/span>;<\/span>\n    }<\/span>\n\n    public<\/span> void<\/span> setName<\/span>(<\/span>String<\/span> name<\/span>)<\/span> {<\/span>\n        this<\/span>.<\/span>name<\/span> =<\/span> name<\/span>;<\/span>\n    }<\/span>\n\n    public<\/span> String<\/span> getEmail<\/span>()<\/span> {<\/span>\n        return<\/span> email<\/span>;<\/span>\n    }<\/span>\n\n    public<\/span> void<\/span> setEmail<\/span>(<\/span>String<\/span> email<\/span>)<\/span> {<\/span>\n        this<\/span>.<\/span>email<\/span> =<\/span> email<\/span>;<\/span>\n    }<\/span>\n\n    public<\/span> boolean<\/span> isBlocked<\/span>()<\/span> {<\/span>\n        return<\/span> isBlocked<\/span>;<\/span>\n    }<\/span>\n\n    public<\/span> void<\/span> setBlocked<\/span>(<\/span>boolean<\/span> blocked<\/span>)<\/span> {<\/span>\n        isBlocked<\/span> =<\/span> blocked<\/span>;<\/span>\n    }<\/span>\n\n    public<\/span> boolean<\/span> isActive<\/span>()<\/span> {<\/span>\n        return<\/span> isActive<\/span>;<\/span>\n    }<\/span>\n\n    public<\/span> void<\/span> setActive<\/span>(<\/span>boolean<\/span> active<\/span>)<\/span> {<\/span>\n        isActive<\/span> =<\/span> active<\/span>;<\/span>\n    }<\/span>\n}<\/span>  <\/code><\/pre><\/figure>\n\n
Does it look familiar? You have certainly come across such a code before.  In accordance with best practices - fields are private. But adding getters and setters does not improve the situation (because we have the same access to variables - as if they were public). So how to deal with this problem?\nThe answer is the Rich Domain Model<\/strong> you are about to read about.<\/p>\n\n
Why is public unsafe?<\/h2>\n
Let\u2019s go back to the first example.<\/p>\n\n
public<\/span> class<\/span> User<\/span> {<\/span>  \n public<\/span> UUID<\/span> userId<\/span>;<\/span>  \n public<\/span> String<\/span> name<\/span>;<\/span>  \n public<\/span> String<\/span> email<\/span>;<\/span>  \n public<\/span> boolean<\/span> isBlocked<\/span>;<\/span>   \n public<\/span> boolean<\/span> isActive<\/span>;<\/span>\n}<\/span>\n  <\/code><\/pre><\/figure>\n\n
The User<\/code> class above exposes its implementation, which in this case is very dangerous. Why? We can freely manipulate all the fields in this class. You can set any field without any consequences. Another problem can be changing the user id at any time in the code.<\/p>\n\n
Anemic Domain Model in Java<\/h2>\n
A class with state exposed by getters and setters is an Anemic Model. An anemic domain model is often used as DTO (Data Transfer Object<\/em>) object - a class with private fields and setters and getters. With an anemic approach, our models become just \u201ccontainers\u201d for the data, and all the logic for operating on that data is extracted to classes such as: **Service<\/code>, **Helper<\/code>, **Processor<\/code>, etc.<\/p>\n\n
What do you think the UserService<\/code> class might look like? Let\u2019s put together some requirements:<\/p>\n