Android APIs
public class

RelativeLayout

extends ViewGroup
java.lang.Object
   ↳ android.view.View
     ↳ android.view.ViewGroup
       ↳ android.widget.RelativeLayout
Known Direct Subclasses

Class Overview

A Layout where the positions of the children can be described in relation to each other or to the parent.

Note that you cannot have a circular dependency between the size of the RelativeLayout and the position of its children. For example, you cannot have a RelativeLayout whose height is set to WRAP_CONTENT and a child set to ALIGN_PARENT_BOTTOM.

Note: In platform version 17 and lower, RelativeLayout was affected by a measurement bug that could cause child views to be measured with incorrect MeasureSpec values. (See MeasureSpec.makeMeasureSpec for more details.) This was triggered when a RelativeLayout container was placed in a scrolling container, such as a ScrollView or HorizontalScrollView. If a custom view not equipped to properly measure with the MeasureSpec mode UNSPECIFIED was placed in a RelativeLayout, this would silently work anyway as RelativeLayout would pass a very large AT_MOST MeasureSpec instead.

This behavior has been preserved for apps that set android:targetSdkVersion="17" or older in their manifest's uses-sdk tag for compatibility. Apps targeting SDK version 18 or newer will receive the correct behavior

See the Relative Layout guide.

Also see RelativeLayout.LayoutParams for layout attributes

Summary

Nested Classes
class RelativeLayout.LayoutParams Per-child layout information associated with RelativeLayout. 
XML Attributes
Attribute Name Related Method Description
android:gravity setGravity(int) Specifies how an object should position its content, on both the X and Y axes, within its own bounds. 
android:ignoreGravity setIgnoreGravity(int) Indicates what view should not be affected by gravity. 
[Expand]
Inherited XML Attributes
From class android.view.ViewGroup
From class android.view.View
Constants
int ABOVE Rule that aligns a child's bottom edge with another child's top edge.
int ALIGN_BASELINE Rule that aligns a child's baseline with another child's baseline.
int ALIGN_BOTTOM Rule that aligns a child's bottom edge with another child's bottom edge.
int ALIGN_END Rule that aligns a child's end edge with another child's end edge.
int ALIGN_LEFT Rule that aligns a child's left edge with another child's left edge.
int ALIGN_PARENT_BOTTOM Rule that aligns the child's bottom edge with its RelativeLayout parent's bottom edge.
int ALIGN_PARENT_END Rule that aligns the child's end edge with its RelativeLayout parent's end edge.
int ALIGN_PARENT_LEFT Rule that aligns the child's left edge with its RelativeLayout parent's left edge.
int ALIGN_PARENT_RIGHT Rule that aligns the child's right edge with its RelativeLayout parent's right edge.
int ALIGN_PARENT_START Rule that aligns the child's start edge with its RelativeLayout parent's start edge.
int ALIGN_PARENT_TOP Rule that aligns the child's top edge with its RelativeLayout parent's top edge.
int ALIGN_RIGHT Rule that aligns a child's right edge with another child's right edge.
int ALIGN_START Rule that aligns a child's start edge with another child's start edge.
int ALIGN_TOP Rule that aligns a child's top edge with another child's top edge.
int BELOW Rule that aligns a child's top edge with another child's bottom edge.
int CENTER_HORIZONTAL Rule that centers the child horizontally with respect to the bounds of its RelativeLayout parent.
int CENTER_IN_PARENT Rule that centers the child with respect to the bounds of its RelativeLayout parent.
int CENTER_VERTICAL Rule that centers the child vertically with respect to the bounds of its RelativeLayout parent.
int END_OF Rule that aligns a child's start edge with another child's end edge.
int LEFT_OF Rule that aligns a child's right edge with another child's left edge.
int RIGHT_OF Rule that aligns a child's left edge with another child's right edge.
int START_OF Rule that aligns a child's end edge with another child's start edge.
int TRUE
[Expand]
Inherited Constants
From class android.view.ViewGroup
From class android.view.View
[Expand]
Inherited Fields
From class android.view.View
Public Constructors
RelativeLayout(Context context)
RelativeLayout(Context context, AttributeSet attrs)
RelativeLayout(Context context, AttributeSet attrs, int defStyle)
Public Methods
boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event)
Dispatches an AccessibilityEvent to the View first and then to its children for adding their text content to the event.
RelativeLayout.LayoutParams generateLayoutParams(AttributeSet attrs)
Returns a new set of layout parameters based on the supplied attributes set.
int getBaseline()

Return the offset of the widget's text baseline from the widget's top boundary.

int getGravity()
Describes how the child views are positioned.
void onInitializeAccessibilityEvent(AccessibilityEvent event)
Initializes an AccessibilityEvent with information about this View which is the event source.
void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info)
Initializes an AccessibilityNodeInfo with information about this view.
void requestLayout()
Call this when something has changed which has invalidated the layout of this view.
void setGravity(int gravity)
Describes how the child views are positioned.
void setHorizontalGravity(int horizontalGravity)
void setIgnoreGravity(int viewId)
Defines which View is ignored when the gravity is applied.
void setVerticalGravity(int verticalGravity)
boolean shouldDelayChildPressedState()
Return true if the pressed state should be delayed for children or descendants of this ViewGroup.
Protected Methods
boolean checkLayoutParams(ViewGroup.LayoutParams p)
ViewGroup.LayoutParams generateDefaultLayoutParams()
Returns a set of layout parameters with a width of WRAP_CONTENT, a height of WRAP_CONTENT and no spanning.
ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p)
Returns a safe set of layout parameters based on the supplied layout params.
void onLayout(boolean changed, int l, int t, int r, int b)
Called from layout when this view should assign a size and position to each of its children.
void onMeasure(int widthMeasureSpec, int heightMeasureSpec)

Measure the view and its content to determine the measured width and the measured height.

[Expand]
Inherited Methods
From class android.view.ViewGroup
From class android.view.View
From class java.lang.Object
From interface android.graphics.drawable.Drawable.Callback
From interface android.view.KeyEvent.Callback
From interface android.view.ViewManager
From interface android.view.ViewParent
From interface android.view.accessibility.AccessibilityEventSource

XML Attributes

android:gravity

Specifies how an object should position its content, on both the X and Y axes, within its own bounds.

Must be one or more (separated by '|') of the following constant values.

ConstantValueDescription
top0x30 Push object to the top of its container, not changing its size.
bottom0x50 Push object to the bottom of its container, not changing its size.
left0x03 Push object to the left of its container, not changing its size.
right0x05 Push object to the right of its container, not changing its size.
center_vertical0x10 Place object in the vertical center of its container, not changing its size.
fill_vertical0x70 Grow the vertical size of the object if needed so it completely fills its container.
center_horizontal0x01 Place object in the horizontal center of its container, not changing its size.
fill_horizontal0x07 Grow the horizontal size of the object if needed so it completely fills its container.
center0x11 Place the object in the center of its container in both the vertical and horizontal axis, not changing its size.
fill0x77 Grow the horizontal and vertical size of the object if needed so it completely fills its container.
clip_vertical0x80 Additional option that can be set to have the top and/or bottom edges of the child clipped to its container's bounds. The clip will be based on the vertical gravity: a top gravity will clip the bottom edge, a bottom gravity will clip the top edge, and neither will clip both edges.
clip_horizontal0x08 Additional option that can be set to have the left and/or right edges of the child clipped to its container's bounds. The clip will be based on the horizontal gravity: a left gravity will clip the right edge, a right gravity will clip the left edge, and neither will clip both edges.
start0x00800003 Push object to the beginning of its container, not changing its size.
end0x00800005 Push object to the end of its container, not changing its size.

This corresponds to the global attribute resource symbol gravity.

Related Methods

android:ignoreGravity

Indicates what view should not be affected by gravity.

Must be a reference to another resource, in the form "@[+][package:]type:name" or to a theme attribute in the form "?[package:][type:]name".

This corresponds to the global attribute resource symbol ignoreGravity.

Related Methods

Constants

public static final int ABOVE

Added in API level 1

Rule that aligns a child's bottom edge with another child's top edge.

Constant Value: 2 (0x00000002)

public static final int ALIGN_BASELINE

Added in API level 1

Rule that aligns a child's baseline with another child's baseline.

Constant Value: 4 (0x00000004)

public static final int ALIGN_BOTTOM

Added in API level 1

Rule that aligns a child's bottom edge with another child's bottom edge.

Constant Value: 8 (0x00000008)

public static final int ALIGN_END

Added in API level 17

Rule that aligns a child's end edge with another child's end edge.

Constant Value: 19 (0x00000013)

public static final int ALIGN_LEFT

Added in API level 1

Rule that aligns a child's left edge with another child's left edge.

Constant Value: 5 (0x00000005)

public static final int ALIGN_PARENT_BOTTOM

Added in API level 1

Rule that aligns the child's bottom edge with its RelativeLayout parent's bottom edge.

Constant Value: 12 (0x0000000c)

public static final int ALIGN_PARENT_END

Added in API level 17

Rule that aligns the child's end edge with its RelativeLayout parent's end edge.

Constant Value: 21 (0x00000015)

public static final int ALIGN_PARENT_LEFT

Added in API level 1

Rule that aligns the child's left edge with its RelativeLayout parent's left edge.

Constant Value: 9 (0x00000009)

public static final int ALIGN_PARENT_RIGHT

Added in API level 1

Rule that aligns the child's right edge with its RelativeLayout parent's right edge.

Constant Value: 11 (0x0000000b)

public static final int ALIGN_PARENT_START

Added in API level 17

Rule that aligns the child's start edge with its RelativeLayout parent's start edge.

Constant Value: 20 (0x00000014)

public static final int ALIGN_PARENT_TOP

Added in API level 1

Rule that aligns the child's top edge with its RelativeLayout parent's top edge.

Constant Value: 10 (0x0000000a)

public static final int ALIGN_RIGHT

Added in API level 1

Rule that aligns a child's right edge with another child's right edge.

Constant Value: 7 (0x00000007)

public static final int ALIGN_START

Added in API level 17

Rule that aligns a child's start edge with another child's start edge.

Constant Value: 18 (0x00000012)

public static final int ALIGN_TOP

Added in API level 1

Rule that aligns a child's top edge with another child's top edge.

Constant Value: 6 (0x00000006)

public static final int BELOW

Added in API level 1

Rule that aligns a child's top edge with another child's bottom edge.

Constant Value: 3 (0x00000003)

public static final int CENTER_HORIZONTAL

Added in API level 1

Rule that centers the child horizontally with respect to the bounds of its RelativeLayout parent.

Constant Value: 14 (0x0000000e)

public static final int CENTER_IN_PARENT

Added in API level 1

Rule that centers the child with respect to the bounds of its RelativeLayout parent.

Constant Value: 13 (0x0000000d)

public static final int CENTER_VERTICAL

Added in API level 1

Rule that centers the child vertically with respect to the bounds of its RelativeLayout parent.

Constant Value: 15 (0x0000000f)

public static final int END_OF

Added in API level 17

Rule that aligns a child's start edge with another child's end edge.

Constant Value: 17 (0x00000011)

public static final int LEFT_OF

Added in API level 1

Rule that aligns a child's right edge with another child's left edge.

Constant Value: 0 (0x00000000)

public static final int RIGHT_OF

Added in API level 1

Rule that aligns a child's left edge with another child's right edge.

Constant Value: 1 (0x00000001)

public static final int START_OF

Added in API level 17

Rule that aligns a child's end edge with another child's start edge.

Constant Value: 16 (0x00000010)

public static final int TRUE

Added in API level 1

Constant Value: -1 (0xffffffff)

Public Constructors

public RelativeLayout (Context context)

Added in API level 1

public RelativeLayout (Context context, AttributeSet attrs)

Added in API level 1

public RelativeLayout (Context context, AttributeSet attrs, int defStyle)

Added in API level 1

Public Methods

public boolean dispatchPopulateAccessibilityEvent (AccessibilityEvent event)

Added in API level 4

Dispatches an AccessibilityEvent to the View first and then to its children for adding their text content to the event. Note that the event text is populated in a separate dispatch path since we add to the event not only the text of the source but also the text of all its descendants. A typical implementation will call onPopulateAccessibilityEvent(AccessibilityEvent) on the this view and then call the dispatchPopulateAccessibilityEvent(AccessibilityEvent) on each child. Override this method if custom population of the event text content is required.

If an View.AccessibilityDelegate has been specified via calling setAccessibilityDelegate(AccessibilityDelegate) its dispatchPopulateAccessibilityEvent(View, AccessibilityEvent) is responsible for handling this call.

Note: Accessibility events of certain types are not dispatched for populating the event text via this method. For details refer to AccessibilityEvent.

Parameters
event The event.
Returns
  • True if the event population was completed.

public RelativeLayout.LayoutParams generateLayoutParams (AttributeSet attrs)

Added in API level 1

Returns a new set of layout parameters based on the supplied attributes set.

Parameters
attrs the attributes to build the layout parameters from
Returns

public int getBaseline ()

Added in API level 1

Return the offset of the widget's text baseline from the widget's top boundary. If this widget does not support baseline alignment, this method returns -1.

Returns
  • the offset of the baseline within the widget's bounds or -1 if baseline alignment is not supported

public int getGravity ()

Added in API level 16

Describes how the child views are positioned.

Related XML Attributes
Returns
  • the gravity.

public void onInitializeAccessibilityEvent (AccessibilityEvent event)

Added in API level 14

Initializes an AccessibilityEvent with information about this View which is the event source. In other words, the source of an accessibility event is the view whose state change triggered firing the event.

Example: Setting the password property of an event in addition to properties set by the super implementation:

 public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
     super.onInitializeAccessibilityEvent(event);
     event.setPassword(true);
 }

If an View.AccessibilityDelegate has been specified via calling setAccessibilityDelegate(AccessibilityDelegate) its onInitializeAccessibilityEvent(View, AccessibilityEvent) is responsible for handling this call.

Note: Always call the super implementation before adding information to the event, in case the default implementation has basic information to add.

Parameters
event The event to initialize.

public void onInitializeAccessibilityNodeInfo (AccessibilityNodeInfo info)

Added in API level 14

Initializes an AccessibilityNodeInfo with information about this view. The base implementation sets:

Subclasses should override this method, call the super implementation, and set additional attributes.

If an View.AccessibilityDelegate has been specified via calling setAccessibilityDelegate(AccessibilityDelegate) its onInitializeAccessibilityNodeInfo(View, AccessibilityNodeInfo) is responsible for handling this call.

Parameters
info The instance to initialize.

public void requestLayout ()

Added in API level 1

Call this when something has changed which has invalidated the layout of this view. This will schedule a layout pass of the view tree. This should not be called while the view hierarchy is currently in a layout pass (isInLayout(). If layout is happening, the request may be honored at the end of the current layout pass (and then layout will run again) or after the current frame is drawn and the next layout occurs.

Subclasses which override this method should call the superclass method to handle possible request-during-layout errors correctly.

public void setGravity (int gravity)

Added in API level 1

Describes how the child views are positioned. Defaults to Gravity.START | Gravity.TOP.

Note that since RelativeLayout considers the positioning of each child relative to one another to be significant, setting gravity will affect the positioning of all children as a single unit within the parent. This happens after children have been relatively positioned.

Related XML Attributes
Parameters
gravity See Gravity

public void setHorizontalGravity (int horizontalGravity)

Added in API level 1

public void setIgnoreGravity (int viewId)

Added in API level 1

Defines which View is ignored when the gravity is applied. This setting has no effect if the gravity is Gravity.START | Gravity.TOP.

Related XML Attributes
Parameters
viewId The id of the View to be ignored by gravity, or 0 if no View should be ignored.
See Also

public void setVerticalGravity (int verticalGravity)

Added in API level 1

public boolean shouldDelayChildPressedState ()

Added in API level 14

Return true if the pressed state should be delayed for children or descendants of this ViewGroup. Generally, this should be done for containers that can scroll, such as a List. This prevents the pressed state from appearing when the user is actually trying to scroll the content. The default implementation returns true for compatibility reasons. Subclasses that do not scroll should generally override this method and return false.

Protected Methods

protected boolean checkLayoutParams (ViewGroup.LayoutParams p)

Added in API level 1

protected ViewGroup.LayoutParams generateDefaultLayoutParams ()

Added in API level 1

Returns a set of layout parameters with a width of WRAP_CONTENT, a height of WRAP_CONTENT and no spanning.

Returns
  • a set of default layout parameters or null

protected ViewGroup.LayoutParams generateLayoutParams (ViewGroup.LayoutParams p)

Added in API level 1

Returns a safe set of layout parameters based on the supplied layout params. When a ViewGroup is passed a View whose layout params do not pass the test of checkLayoutParams(android.view.ViewGroup.LayoutParams), this method is invoked. This method should return a new set of layout params suitable for this ViewGroup, possibly by copying the appropriate attributes from the specified set of layout params.

Parameters
p The layout parameters to convert into a suitable set of layout parameters for this ViewGroup.
Returns

protected void onLayout (boolean changed, int l, int t, int r, int b)

Added in API level 1

Called from layout when this view should assign a size and position to each of its children. Derived classes with children should override this method and call layout on each of their children.

Parameters
changed This is a new size or position for this view
l Left position, relative to parent
t Top position, relative to parent
r Right position, relative to parent
b Bottom position, relative to parent

protected void onMeasure (int widthMeasureSpec, int heightMeasureSpec)

Added in API level 1

Measure the view and its content to determine the measured width and the measured height. This method is invoked by measure(int, int) and should be overriden by subclasses to provide accurate and efficient measurement of their contents.

CONTRACT: When overriding this method, you must call setMeasuredDimension(int, int) to store the measured width and height of this view. Failure to do so will trigger an IllegalStateException, thrown by measure(int, int). Calling the superclass' onMeasure(int, int) is a valid use.

The base class implementation of measure defaults to the background size, unless a larger size is allowed by the MeasureSpec. Subclasses should override onMeasure(int, int) to provide better measurements of their content.

If this method is overridden, it is the subclass's responsibility to make sure the measured height and width are at least the view's minimum height and width (getSuggestedMinimumHeight() and getSuggestedMinimumWidth()).

Parameters
widthMeasureSpec horizontal space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec.
heightMeasureSpec vertical space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec.