Add Constructor to UML Class

A constructor is a procedure called to create a class. This tutorial shows you how to add a constructor to a class in your UML diagram easily.

What is a Constructor in UML Class Diagram?

A constructor is an operation within a UML class. It is annotated with «create» stereotype. A constructor is a special operation (or method) that is used to initialize a class instance. A constructor may be parameterless or it may include a list of parameters that have to be set to initialize a class instance properly.

How to Add a Constructor?

  1. Select a class to which you want to add a constructor.
  2. Click on Add Constructor in the context bar.
  3. New Constructor dialog will show. In the dialog, choose the attributes you want to include in the constructor as its parameters.
  4. Click on OK to confirm the dialog and insert the new constructor.
Add Contructor to UML Class
Add Contructor to UML Class

Various Methods of Constructor Creation

Consider a class in your diagram with several properties or attributes. There are several methods you can add a constructor to the class.

Method 1: Manual Constructor Addition

  • Add a new operation to your class.
  • Name this operation after the class itself and add a 'create' stereotype.
  • This method is simple but might become less efficient if your constructor requires multiple parameters.

Method 2: Using the 'Add Constructor' Context Button

This method is more efficient, especially for constructors with numerous parameters.

  • Select the class in your diagram. A context bar will appear under the selected class.
  • Find and click the 'Add Constructor' button in this context bar.
  • A dialog box will open, allowing you to select which attributes to initialize in the constructor. You can also add more parameters later in the diagram editor.
  • After making your choices, click 'OK' to confirm and add the constructor to the class.

Method 3: Shortcut Key Method

Adding constructors using shortcut keys is a quick alternative.

  • Use the relevant shortcut key that corresponds to the constructor button in the context bar - in our case, it is the fourth button, so we press ALT+4.
  • This opens the 'New Constructor' dialog.
  • In the dialog, use the 'Select All' option to choose all attributes, and then click 'OK'.
  • This action will create a new constructor that initializes all chosen attributes and adds it to the class operations list.

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