# Class Diagram

![Class Diagram](https://content.gitbook.com/content/aNbtXAm2MUsbrMlAEZb1/blobs/vGMy7LyqD1FyizNJbOJr/Class%20Diagram!UML%20Property_6.png)

## Create Class Diagram

To create a Class Diagram:

1. First select an element where a new Class Diagram to be contained as a child.
2. Select **Model | Add Diagram | Class Diagram** in the Menu Bar or select **Add Diagram | Class Diagram** in Context Menu.

> **See also**
>
> [UML Class Diagram](http://www.uml-diagrams.org/class-diagrams-overview.html) - For more information about UML Class Diagram.

## Model Element

Model Element is an abstract element of all UML model elements.

You can use **QuickEdit** for Model Element by double-click or press `Enter` on a selected model element.

* **Name Expression** : Edit name expression.

  *Syntax of Name Expression*

  ```
  expression ::= [ '<<' stereotype `>>` ] [ visibility ] name
  stereotype ::= (identifier)
  visibility ::= '+' | '#' | '-' | '~'
  name ::= (identifier)
  ```
* **Visibility** : Change visibility property.
* **Add Note** : Add a linked note.
* **Add Constraint** : Add a constraint.

## Classifier

Classifier is an abstract element of:

* [Class](#class)
* [Interface](#interface)
* [Signal](#signal)
* [DataType](#datatype)
* [PrimitiveType](#primitivetype)
* [Enumeration](#enumeration)
* [Component](https://docs.staruml.io/component-diagram#component)
* [Artifact](https://docs.staruml.io/component-diagram#artifact)

You can use **QuickEdit** for Classifier by double-click or press `Enter` on a selected classifier.

* **Name Expression** : Edit name expression.

  *Syntax of Name Expression*

  ```
  expression ::= [ '<<' stereotype `>>` ] [ visibility ] name
  stereotype ::= (identifier)
  visibility ::= '+' | '#' | '-' | '~'
  name ::= (identifier)
  ```
* **Visibility** : Change visibility property.
* **Add Note** : Add a linked note.
* **Add Constraint** : Add a constraint.
* **Add Attribute** (`Ctrl+Enter`) : Add an attribute.
* **Add Operation** (`Ctrl+Shift+Enter`) : Add an operation.
* **Add Reception** : Add a reception.

## Class

To create a Class:

1. Select **Class** in **Toolbox**.
2. Drag on the diagram as the size of Class.

To create a Class (model element only) by Menu:

1. Select an Element where a new Class to be contained.
2. Select **Model | Add | Class** in Menu Bar or **Add | Class** in Context Menu.

You can use **QuickEdit** for Class by double-click or press `Enter` on a selected Class.

* **Name Expression** : Edit name expression.

  *Syntax of Name Expression*

  ```
  expression ::= [ '<<' stereotype `>>` ] [ visibility ] name
  stereotype ::= (identifier)
  visibility ::= '+' | '#' | '-' | '~'
  name ::= (identifier)
  ```
* **Visibility** : Change visibility property.
* **Add Note** : Add a linked note.
* **Add Constraint** : Add a constraint.
* **Add Attribute** (`Ctrl+Enter`) : Add an attribute.
* **Add Operation** (`Ctrl+Shift+Enter`) : Add an operation.
* **Add Template Parameter** : Add a template parameter.
* **Add Reception** : Add a reception.
* **Add Sub-Class** : Add a sub-class.
* **Add Super-Class** : Add a super class.
* **Add Provided Interface** : Add a provided interface.
* **Add Required Interface** : Add a required interface.
* **Add Associated Class** : Add an associated class.
* **Add Aggregated Class** : Add an aggregated class.
* **Add Composited Class** : Add a composited class.
* **Add Port** : Add a port.
* **Add Part** : Add a part.

To suppress Attributes, see [Suppress Attributes](https://docs.staruml.io/user-guide/formatting-diagram#suppress-attributes).

To suppress Operations, see [Suppress Operations](https://docs.staruml.io/user-guide/formatting-diagram#suppress-operations).

To suppress Receptions, see [Suppress Receptions](https://docs.staruml.io/user-guide/formatting-diagram#suppress-receptions).

To show or hide Operation Signatures, see [Show Operation Signature](https://docs.staruml.io/user-guide/formatting-diagram#show-operation-signature).

## Attribute

To add an Attribute:

1. Select a Classifier.
2. Select **Model | Add | Attribute** in Menu Bar or **Add | Attribute** in Context Menu.

You can use **QuickEdit** for Attribute by double-click or press `Enter` on a selected Attribute.

* **Attribute Expression** : Edit Attribute expression.

  *Syntax of Attribute Expression*

  ```
  attribute ::= [ '<<' stereotype `>>` ] [ visibility ] name [':' type ] [ '[' multiplicity ']' ] [ '=' defaut-value ]
  stereotype ::= (identifier)
  visibility ::= '+' | '#' | '-' | '~'
  name ::= (identifier)
  type ::= (identifier)
  multiplicity ::= multiplicity-bound [ '..' multiplicity-bound ]
  multiplicity-bound ::= (number) | '*'
  default-value ::= (string)
  ```
* **Visibility** : Change visibility property.
* **Add** (`Ctrl+Enter`) : Add one more attribute in the below.
* **Delete** (`Ctrl+Delete`) : Delete the attribute
* **Move Up** (`Ctrl+Up`) : Move the attribute up.
* **Move Down** (`Ctrl+Down`) : Move the attribute down.

## Operation

To add an Operation:

1. Select a Classifier.
2. Select **Model | Add | Operation** in Menu Bar or **Add | Operation** in Context Menu.

You can use **QuickEdit** for Operation by double-click or press `Enter` on a selected Operation.

* **Operation Expression** : Edit Operation expression.

  *Syntax of Operation Expression*

  ```
  operation ::= [ '<<' stereotype `>>` ] [ visibility ] name [ '(' parameter-list ')' ] [ ':' return-type ]
  stereotype ::= (identifier)
  visibility ::= '+' | '#' | '-' | '~'
  name ::= (identifier)
  parameter-list ::= parameter [ ',' parameter ]*
  parameter ::= (identifier)
  return-type ::= (identifier)
  ```
* **Visibility** : Change visibility property.
* **Add** (`Ctrl+Enter`) : Add one more operation in the below.
* **Delete** (`Ctrl+Delete`) : Delete the operation
* **Move Up** (`Ctrl+Up`) : Move the operation up.
* **Move Down** (`Ctrl+Down`) : Move the operation down.

To add a Parameter, see [Parameter](#parameter).

To show or hide Operation Signatures, see [Show Operation Signature](https://docs.staruml.io/user-guide/formatting-diagram#show-operation-signature).

## Parameter

To add a Parameter:

1. Select an Operation.
2. Select **Model | Add | Parameter** in Menu Bar or **Add | Parameter** in Context Menu.

## Template Parameter

To add a Template Parameter:

1. Select an Element.
2. Select **Model | Add | Template Parameter** in Menu Bar or **Add | Template Parameter** in Context Menu.

You can use **QuickEdit** for Template Parameter by double-click or press `Enter` on a selected Template Parameter.

* **Template Parameter Expression** : Edit Template Parameter expression.

  *Syntax of Template Parameter Expression*

  ```
  template-parameter ::= [ '<<' stereotype `>>` ] [ visibility ] name [':' type ] [ '=' defaut-value ]
  stereotype ::= (identifier)
  visibility ::= '+' | '#' | '-' | '~'
  name ::= (identifier)
  type ::= (identifier)
  default-value ::= (string)
  ```
* **Visibility** : Change visibility property.
* **Add** (`Ctrl+Enter`) : Add one more template parameter in the below.
* **Delete** (`Ctrl+Delete`) : Delete the template parameter.
* **Move Up** (`Ctrl+Up`) : Move the template parameter up.
* **Move Down** (`Ctrl+Down`) : Move the template parameter down.

## Template Parameter Substitution

To add a Template Parameter Substituion:

1. Select a Template Binding element.
2. Select **Model | Add | Template Parameter Substitution** in Menu Bar or **Add | Template Parameter Substitution** in Context Menu.

Each **Template Parameter Substitution** should have `formal` property assigned to a **Template Parameter** of the template element and `actual` property assigned to the actual value for the template parameter.

## Interface

To create an Interface:

1. Select **Interface** in **Toolbox**.
2. Drag on the diagram as the size of Interface.

To create an Interface (model element only) by Menu:

1. Select an Element where a new Interface to be contained.
2. Select **Model | Add | Interface** in Menu Bar or **Add | Interface** in Context Menu.

You can use **QuickEdit** for Interface by double-click or press `Enter` on a selected Interface.

* **Name Expression** : Edit name expression.

  *Syntax of Name Expression*

  ```
  expression ::= [ '<<' stereotype `>>` ] [ visibility ] name
  stereotype ::= (identifier)
  visibility ::= '+' | '#' | '-' | '~'
  name ::= (identifier)
  ```
* **Visibility** : Change visibility property.
* **Add Note** : Add a linked note.
* **Add Constraint** : Add a constraint.
* **Add Attribute** (`Ctrl+Enter`) : Add an attribute.
* **Add Operation** (`Ctrl+Shift+Enter`) : Add an operation.
* **Add Reception** : Add a reception.
* **Add Sub-Interface** : Add a sub-interface.
* **Add Super-Interface** : Add a super interface.
* **Add Realizing Class** : Add an realizing class.

To show an Interface as Lollipop notation, Interface should be realized (See [Interface Realization](#interface-realization)) and then change Stereotype Display to Icon or Icon with Label (See [Stereotype Display](https://docs.staruml.io/user-guide/formatting-diagram#stereotype-display)).

To show an Interface as Socket notation, Interface should have dependants (See [Dependency](#dependency)) and then change Stereotype Display to Icon or Icon with Label (See [Stereotype Display](https://docs.staruml.io/user-guide/formatting-diagram#stereotype-display)).

To suppress Attributes, see [Suppress Attributes](https://docs.staruml.io/user-guide/formatting-diagram#suppress-attributes).

To suppress Operations, see [Suppress Operations](https://docs.staruml.io/user-guide/formatting-diagram#suppress-operations).

To suppress Receptions, see [Suppress Receptions](https://docs.staruml.io/user-guide/formatting-diagram#suppress-receptions).

To show or hide Operation Signatures, see [Show Operation Signature](https://docs.staruml.io/user-guide/formatting-diagram#show-operation-signature).

## Signal

To create a Signal:

1. Select **Signal** in **Toolbox**.
2. Drag on the diagram as the size of Signal.

To create a Signal (model element only) by Menu:

1. Select an Element where a new Signal to be contained.
2. Select **Model | Add | Signal** in Menu Bar or **Add | Signal** in Context Menu.

You can use **QuickEdit** for Classifier (See [Classifier](#classifier)).

## DataType

To create a DataType:

1. Select **DataType** in **Toolbox**.
2. Drag on the diagram as the size of DataType.

To create a DataType (model element only) by Menu:

1. Select an Element where a new DataType to be contained.
2. Select **Model | Add | DataType** in Menu Bar or **Add | DataType** in Context Menu.

You can use **QuickEdit** for Classifier (See [Classifier](#classifier)).

## PrimitiveType

To create a PrimitiveType:

1. Select **PrimitiveType** in **Toolbox**.
2. Drag on the diagram as the size of PrimitiveType.

To create a PrimitiveType (model element only) by Menu:

1. Select an Element where a new PrimitiveType to be contained.
2. Select **Model | Add | PrimitiveType** in Menu Bar or **Add | PrimitiveType** in Context Menu.

You can use **QuickEdit** for Classifier (See [Classifier](#classifier)).

## Enumeration

To create an Enumeration:

1. Select **Enumeration** in **Toolbox**.
2. Drag on the diagram as the size of Enumeration.

To create an Enumeration (model element only) by Menu:

1. Select an Element where a new Enumeration to be contained.
2. Select **Model | Add | Enumeration** in Menu Bar or **Add | Enumeration** in Context Menu.

You can use **QuickEdit** for Enumeration by double-click or press `Enter` on a selected Enumeration.

* **Name Expression** : Edit name expression.

  *Syntax of Name Expression*

  ```
  expression ::= [ '<<' stereotype `>>` ] [ visibility ] name
  stereotype ::= (identifier)
  visibility ::= '+' | '#' | '-' | '~'
  name ::= (identifier)
  ```
* **Visibility** : Change visibility property.
* **Add Note** : Add a linked note.
* **Add Constraint** : Add a constraint.
* **Add Literal** (`Ctrl+Enter`) : Add an enumeration literal.
* **Add Operation** (`Ctrl+Shift+Enter`) : Add an operation.

To suppress Literals, see see [Suppress Literals](https://docs.staruml.io/user-guide/formatting-diagram#suppress-literals).

## Enumeration Literal

To add an Enumeration Literal:

1. Select a Classifier.
2. Select **Model | Add | Enumeration Literal** in Menu Bar or **Add | Enumeration Literal** in Context Menu.

You can use **QuickEdit** for Enumeration Literal by double-click or press `Enter` on a selected Enumeration Literal.

* **Name Expression** : Edit name expression.

  *Syntax of Name Expression*

  ```
  expression ::= [ '<<' stereotype `>>` ] [ visibility ] name
  stereotype ::= (identifier)
  visibility ::= '+' | '#' | '-' | '~'
  name ::= (identifier)
  ```
* **Visibility** : Change visibility property.
* **Add** (`Ctrl+Enter`) : Add one more literal in the below.
* **Delete** (`Ctrl+Delete`) : Delete the literal
* **Move Up** (`Ctrl+Up`) : Move the literal up.
* **Move Down** (`Ctrl+Down`) : Move the literal down.

## Relationship

Relationship is an abstract element representing a relationship between UML elements.

Subclasses of Relationship are:

* [Generalization](#generalization)
* [Association](#association)
* [Aggregation](#aggregation)
* [Composition](#composition)
* [Dependency](#dependency)
* [Interface Realization](#interface-realization)
* [Component Realization](https://docs.staruml.io/component-diagram#component-realization)
* [Include](https://docs.staruml.io/use-case-diagram#include)
* [Exclude](https://docs.staruml.io/use-case-diagram#exclude)

![QuickEdits for Relationship](https://content.gitbook.com/content/aNbtXAm2MUsbrMlAEZb1/blobs/jssPG3DonwqyofVHSQRf/relationship.png)

You can use **QuickEdit** by double-click or press `Enter` on a selected relationship.

* **Name Expression** : Edit name expression.

  *Syntax of Name Expression*

  ```
  expression ::= [ '<<' stereotype `>>` ] [ visibility ] name
  stereotype ::= (identifier)
  visibility ::= '+' | '#' | '-' | '~'
  name ::= (identifier)
  ```
* **Visibility** : Change visibility property.
* **Add Note** : Add a linked note.
* **Add Constraint** : Add a constraint.

## Generalization

To create a Generalization:

1. Select **Generalization** in **Toolbox**.
2. Drag from an element (to be special) and drop on another element (to be general).

You can use **QuickEdit** for Relationship (See [Relationship](#relationship)).

## Association

To create an Association (or Directed Association):

1. Select **Association** (or **Directed Association**) in **Toolbox**.
2. Drag from an element and drop on another element.

You can use **QuickEdit** for Relationship (See [Relationship](#relationship)).

You can also use **QuickEdit** for Association End by double-click at the end side of an Association.

* **Name Expression** : Edit name expression.

  *Syntax of Name Expression*

  ```
  expression ::= [ '<<' stereotype `>>` ] [ visibility ] name
  stereotype ::= (identifier)
  visibility ::= '+' | '#' | '-' | '~'
  name ::= (identifier)
  ```
* **Visibility** : Change visibility property.
* **Navigability** : Change navigable property.
* **Aggregation Kind** : Change aggregationKind property.
* **Multiplicity** : Change multiplicity property.
* **Add Qualifier** : Add a qualifier (attribute) to the AssociationEnd.

### Order of Ends

You can show an arrow representing order of ends. If you want to show arrow from end1 to end2, then select `forward` in **QuickEdit**. Or, you want to show arrow from end2 to end1, then select `backward`. You can also hide the arrow by selecting `hide`.

![Order of Ends](https://content.gitbook.com/content/aNbtXAm2MUsbrMlAEZb1/blobs/TXhftmp2munhjqoju6vY/end-order.png)

### Navigability

You can set `navigable` property of AssociationEnd to one of following:

* `unspecified`
* `navigable`
* `notNavigable`

![Navigability of AssociationEnd](https://content.gitbook.com/content/aNbtXAm2MUsbrMlAEZb1/blobs/dCZ8rjIFaWK0HUKmBFaa/navigable.png)

### N-ary Association

{% hint style="warning" %}
The N-ary association here is different from the UML specification and is not a semantically correct modeling method. Please refer to the UML specification for details.
{% endhint %}

If you want to create N-ary association, you need to create N-ary association node first.

To create an N-ary Association:

1. Select **N-ary Association Node** in Toolbox (Class Advanced)
2. Drag on the diagram as the size of **N-ary Association Node** (diamond shape).
3. Create **Associations** between Classifiers and the **N-ary Association** Node.

![N-ary Association](https://content.gitbook.com/content/aNbtXAm2MUsbrMlAEZb1/blobs/mtuoC6ZjH4nOXLH925so/nary-asso.png)

### Ownership

To show ownership dot on AssociationEnd, assign `ownerAttribute` of AssociationEnd.

![AssociationEnd's ownership notation](https://content.gitbook.com/content/aNbtXAm2MUsbrMlAEZb1/blobs/KEmaE62Qcrd1fdstbyjV/ownership.png)

## Aggregation

To create an Aggregation:

1. Select **Aggregation** in **Toolbox**.
2. Drag from an element (to be a part) and drop on another element (to be whole).

You can use **QuickEdit** for Relationship (See [Relationship](#relationship)).

You can also use **QuickEdit** for AssociationEnd by double-click at the end side of an Association (See [Association](#association)).

> **Note**
>
> Aggregation is an association whose `aggregation` property is `shared`.

## Composition

To create a Composition:

1. Select **Composition** in **Toolbox**.
2. Drag from an element (to be a part) and drop on another element (to be whole).

You can use **QuickEdit** for Relationship (See [Relationship](#relationship)).

You can also use **QuickEdit** for AssociationEnd by double-click at the end side of an Association (See [Association](#association)).

> **Note**
>
> Composition is an association whose `aggregation` property is `composite`.

## Dependency

To create an Dependency:

1. Select **Dependency** in **Toolbox**.
2. Drag from an element (client) and drop on another element (supplier).

You can use **QuickEdit** for Relationship (See [Relationship](#relationship)).

## Interface Realization

To create an Interface Realization:

1. Select **Interface Realization** in **Toolbox**.
2. Drag from an element (realizing) and drop on an interface (to be realized).

You can use **QuickEdit** for Relationship (See [Relationship](#relationship)).

## Association Class

To create an Association Class by linking two Classifiers:

1. Select **Association Class** in **Toolbox**.
2. Drag from an element and drop on another element.
3. An Association and a Class connected to the association will be created.

To create an Association Class by linking Association and Class:

1. Select **Association Class** in **Toolbox**.
2. Drag from an Association (or Class) and drop on a Class (or Association).
3. The Class will be connected to the Association.

## Template Binding

To create a Template Binding:

1. Select **Template Binding** in **Toolbox**.
2. Drag from a bound element and drop on a template element.
3. If required, create [Template Parameter Substitution](#template-parameter-substitution).

You can use **QuickEdit** for Template Binding by double-click or press `Enter`.

* **Visibility** : Change visibility property.
* **Add Note** : Add a linked note.
* **Add Constraint** : Add a constraint.
* **Add Template Parameter** : Add a template parameter substitution.

## Frame

To create a Frame view of a particular model element:

1. Select **Frame** in **Toolbox**.
2. Drag on the diagram as the size of Frame.
3. Select a model element which the Frame represents in **Element Picker Dialog**

You can show model element type in Frame by checking **Format > Show Type** menu item.

You can show model element's namespace in Frame by checking **Format > Show Namespace** menu item.

You can show diagram name in Frame by checking **Format > Show Diagram Name** menu item.

## Tag

To add a Tag of an element:

1. Select an element to add a Tag.
2. Select **Model | Add | Tag** in Menu Bar or **Add | Tag** in Context Menu.

You can select one of tag kinds: **string**, **reference**, **boolean**, **number,** or **enum**. The `value` property corresponds to **string** kind. The `reference` property corresponds to **reference** kind. The `checked` property corresponds to **boolean** kind. The `number` property corresponds to **number** kind. The `value` and `options` property corresponds to **enum** type.

The `options` property should contains items separated by new line character and the `value` property should have one of the item specified in the `options` property.

The Tags can be shown in views by checking **Format** > **Show Property** menu item. If you don't want to be shown, check `hidden` property.

You can manage Tags conveniently in [Tag Editor](https://docs.staruml.io/user-guide/user-interface#tag-editor) with relationships of Stereotype's Attributes.

## Constraint

To add a Constraint of an element:

1. Select an element to add a Constraint.
2. Select **Model | Add | Constraint** in Menu Bar or **Add | Constraint** in Context Menu.

You can create a Constraint view on a diagram by drag and drop from Model Explorer.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.staruml.io/working-with-uml-diagrams/class-diagram.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.