# android.support.constraint

# android.support.constraint

| This package is part of the Android[support library](https://developer.android.com/topic/libraries/support-library)which is no longer maintained. The Constraint Layout support library has been superseded by the[AndroidX Constraint Layout library](https://developer.android.com/reference/androidx/constraintlayout/classes), which is part of[Jetpack](https://developer.android.com/jetpack). We recommend using the AndroidX libraries in all new projects. You should also consider[migrating](https://developer.android.com/jetpack/androidx/migrate)existing projects to AndroidX.

## Classes

|-----------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [Barrier](https://developer.android.com/reference/android/support/constraint/Barrier)                                             | **Added in 1.1** A Barrier references multiple widgets as input, and creates a virtual guideline based on the most extreme widget on the specified side.                                                        |
| [ConstraintLayout](https://developer.android.com/reference/android/support/constraint/ConstraintLayout)                           | A`ConstraintLayout`is a[android.view.ViewGroup](https://developer.android.com/reference/android/view/ViewGroup/package-summary)which allows you to position and size widgets in a flexible way.                 |
| [ConstraintLayout.LayoutParams](https://developer.android.com/reference/android/support/constraint/ConstraintLayout.LayoutParams) | This class contains the different attributes specifying how a view want to be laid out inside a[ConstraintLayout](https://developer.android.com/reference/android/support/constraint/ConstraintLayout).         |
| [ConstraintProperties](https://developer.android.com/reference/android/support/constraint/ConstraintProperties)                   | **Added in 2.0** ConstraintProperties provides an easy to use api to update the layout params of[ConstraintLayout](https://developer.android.com/reference/android/support/constraint/ConstraintLayout)children |
| [ConstraintsChangedListener](https://developer.android.com/reference/android/support/constraint/ConstraintsChangedListener)       | **Added in 2.0** Callbacks on state change                                                                                                                                                                      |
| [ConstraintSet](https://developer.android.com/reference/android/support/constraint/ConstraintSet)                                 | This class allows you to define programmatically a set of constraints to be used with[ConstraintLayout](https://developer.android.com/reference/android/support/constraint/ConstraintLayout).                   |
| [Group](https://developer.android.com/reference/android/support/constraint/Group)                                                 | **Added in 1.1** This class controls the visibility of a set of referenced widgets.                                                                                                                             |
| [Guideline](https://developer.android.com/reference/android/support/constraint/Guideline)                                         | Utility class representing a Guideline helper object for[ConstraintLayout](https://developer.android.com/reference/android/support/constraint/ConstraintLayout).                                                |
| [Placeholder](https://developer.android.com/reference/android/support/constraint/Placeholder)                                     | **Added in 1.1** A`Placeholder`provides a virtual object which can position an existing object.                                                                                                                 |

-

  ## Classes

  - [Barrier](https://developer.android.com/reference/android/support/constraint/Barrier)
  - [ConstraintLayout](https://developer.android.com/reference/android/support/constraint/ConstraintLayout)
  - [ConstraintLayout.LayoutParams](https://developer.android.com/reference/android/support/constraint/ConstraintLayout.LayoutParams)
  - [ConstraintProperties](https://developer.android.com/reference/android/support/constraint/ConstraintProperties)
  - [ConstraintsChangedListener](https://developer.android.com/reference/android/support/constraint/ConstraintsChangedListener)
  - [ConstraintSet](https://developer.android.com/reference/android/support/constraint/ConstraintSet)
  - [Group](https://developer.android.com/reference/android/support/constraint/Group)
  - [Guideline](https://developer.android.com/reference/android/support/constraint/Guideline)
  - [Placeholder](https://developer.android.com/reference/android/support/constraint/Placeholder)