# androidx.constraintlayout.widget

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## Interfaces

|---|---|
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout.ValueModifier` | This is the interface to a valued modifier. implement this and add it using addValueModifier |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/SharedValues.SharedValuesListener` | interface for listeners |

## Classes

|---|---|
| `https://developer.android.com/reference/androidx/constraintlayout/widget/Barrier` | **Added in 1.1** |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintAttribute` | Defines non standard Attributes |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintHelper` | **Added in 1.1** |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout` | A `ConstraintLayout` is a `https://developer.android.com/reference/android/view/ViewGroup.html` which allows you to position and size widgets in a flexible way. |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout.LayoutParams` | This class contains the different attributes specifying how a view want to be laid out inside a `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout`. |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayoutStates` |   |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayoutStatistics` | This provide metrics of the complexity of the layout that is being solved. |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintProperties` | **Added in 2.0** |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintSet` | Defines a set of constraints to be used with `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout`. |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintSet.Constraint` |   |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintSet.Layout` |   |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintSet.Motion` |   |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintSet.PropertySet` |   |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintSet.Transform` |   |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/Constraints` | This defines the internally defined Constraint set It allows you to have a group of References which point to other views and provide them with constraint attributes |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/Constraints.LayoutParams` |   |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintsChangedListener` | **Added in 2.0** |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/Group` | Control the visibility and elevation of the referenced views **Added in 1.1** |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/Guideline` | Utility class representing a Guideline helper object for `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout`. |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/Placeholder` | **Added in 1.1** |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ReactiveGuide` | Utility class representing a reactive Guideline helper object for `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout`. |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/SharedValues` | Shared values |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/StateSet` |   |
| `https://developer.android.com/reference/androidx/constraintlayout/widget/VirtualLayout` | **Added in 2.0** |

## Enums

|---|---|
| `https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintAttribute.AttributeType` |   |