# androidx.constraintlayout.core.widgets

# androidx.constraintlayout.core.widgets

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Kotlin\|[Java](https://developer.android.com/reference/androidx/constraintlayout/core/widgets/package-summary "View this page in Java")

## Interfaces

|--------------------------------------------------------------------------------------------------------|------------------------------|
| [Helper](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/Helper) | interface to virtual objects |

## Classes

|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------|
| [Barrier](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/Barrier)                                     | A Barrier takes multiple widgets                                                             |
| [Chain](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/Chain)                                         | Chain management and constraints creation                                                    |
| [ChainHead](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/ChainHead)                                 | Class to represent a chain by its main elements.                                             |
| [ConstraintAnchor](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/ConstraintAnchor)                   | Model a constraint relation.                                                                 |
| [ConstraintWidget](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/ConstraintWidget)                   | Implements a constraint Widget model supporting constraints relations between other widgets. |
| [ConstraintWidgetContainer](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/ConstraintWidgetContainer) | A container of ConstraintWidget that can layout its children                                 |
| [Flow](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/Flow)                                           | Implements the Flow virtual layout.                                                          |
| [Guideline](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/Guideline)                                 | Guideline                                                                                    |
| [HelperWidget](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/HelperWidget)                           | HelperWidget class                                                                           |
| [Optimizer](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/Optimizer)                                 | Implements direct resolution without using the solver                                        |
| [Placeholder](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/Placeholder)                             | Simple VirtualLayout that center the first referenced widget onto itself.                    |
| [Rectangle](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/Rectangle)                                 | Simple rect class                                                                            |
| [VirtualLayout](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/VirtualLayout)                         | Base class for Virtual layouts                                                               |
| [WidgetContainer](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/WidgetContainer)                     | A container of ConstraintWidget                                                              |

## Enums

|------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------|
| [ConstraintAnchor.Type](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/ConstraintAnchor.Type)                             | Define the type of anchor         |
| [ConstraintWidget.DimensionBehaviour](https://developer.android.com/reference/kotlin/androidx/constraintlayout/core/widgets/ConstraintWidget.DimensionBehaviour) | Define how the widget will resize |