Realization in UML

In this article we will learn how to implement Realization in UML. Realization shows the relationship between an Interface an the class that provides the implementation for the interface.

We can implement this in UML using a closed, hollow arrowhead pointing from the implementation class to the interface with a dashed line.

Interface In UML:
Similar to Class Diagram Structure in UML, we can show Interface Class in UML.

Interface in UML

Realization Example:
Interface Code:

public interface Mammals {
    public String walk();
}

Interface Implementation Class:

public class Cats implements Mammals {
    public String walk() {
        return "Have Instructed Cats to Perform Walk Operation";
    }
}
 
public class Dogs implements Mammals {
    public String walk() {
        return "Have Instructed Dogs to Perform Walk Operation";
    }
}

Realization UML Diagram:

Implementing Realization in UML

Realization relationships

In UML modeling, a realization relationship is a relationship between two model elements, in which one model element (the client) realizes the behavior that the other model element (the supplier) specifies. Several clients can realize the behavior of a single supplier. You can use realization relationships in class diagrams and component diagrams.
Typically, realization relationships do not have names. If you name a realization, the name is displayed beside to the realization connector in the diagram.
As the following figure illustrates, a realization is displayed in the diagram editor as a dashed line with an unfilled arrowhead that points from the client (realizes the behavior) to the supplier (specifies the behavior).

You can model the following situations using realization relationships:

• A component is realized by a set of classifiers that provide its implementation.
• A collaboration instance contains the objects and messages that are needed to implement the behaviors that a use case specifies.

Parent topic: Relationships in component diagrams

Parent topic: Relationships in class diagrams

Parent topic: Relationships between model elements

Related tasks

Specifying relationships in UML diagrams

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