Android APIs
public class

LinearLayout

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

Class Overview

A Layout that arranges its children in a single column or a single row. The direction of the row can be set by calling setOrientation(). You can also specify gravity, which specifies the alignment of all the child elements by calling setGravity() or specify that specific children grow to fill up any remaining space in the layout by setting the weight member of LinearLayout.LayoutParams. The default orientation is horizontal.

See the Linear Layout guide.

Also see android.widget.LinearLayout.LayoutParams for layout attributes

Summary

Nested Classes
class LinearLayout.LayoutParams Per-child layout information associated with ViewLinearLayout. 
XML Attributes
Attribute Name Related Method Description
android:baselineAligned setBaselineAligned(boolean) When set to false, prevents the layout from aligning its children's baselines. 
android:baselineAlignedChildIndex setBaselineAlignedChildIndex(int) When a linear layout is part of another layout that is baseline aligned, it can specify which of its children to baseline align to (that is, which child TextView). 
android:divider setDividerDrawable(Drawable) Drawable to use as a vertical divider between buttons. 
android:gravity setGravity(int) Specifies how an object should position its content, on both the X and Y axes, within its own bounds. 
android:measureWithLargestChild setMeasureWithLargestChildEnabled(boolean) When set to true, all children with a weight will be considered having the minimum size of the largest child. 
android:orientation setOrientation(int) Should the layout be a column or a row? Use "horizontal" for a row, "vertical" for a column. 
android:weightSum Defines the maximum weight sum. 
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Inherited XML Attributes
From class android.view.ViewGroup
From class android.view.View
Constants
int HORIZONTAL
int SHOW_DIVIDER_BEGINNING Show a divider at the beginning of the group.
int SHOW_DIVIDER_END Show a divider at the end of the group.
int SHOW_DIVIDER_MIDDLE Show dividers between each item in the group.
int SHOW_DIVIDER_NONE Don't show any dividers.
int VERTICAL
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Inherited Constants
From class android.view.ViewGroup
From class android.view.View
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Inherited Fields
From class android.view.View
Public Constructors
LinearLayout(Context context)
LinearLayout(Context context, AttributeSet attrs)
LinearLayout(Context context, AttributeSet attrs, int defStyleAttr)
LinearLayout(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)
Public Methods
LinearLayout.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 getBaselineAlignedChildIndex()
Drawable getDividerDrawable()
int getDividerPadding()
Get the padding size used to inset dividers in pixels
int getOrientation()
Returns the current orientation.
int getShowDividers()
float getWeightSum()
Returns the desired weights sum.
boolean isBaselineAligned()

Indicates whether widgets contained within this layout are aligned on their baseline or not.

boolean isMeasureWithLargestChildEnabled()
When true, all children with a weight will be considered having the minimum size of the largest child.
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 setBaselineAligned(boolean baselineAligned)

Defines whether widgets contained in this layout are baseline-aligned or not.

void setBaselineAlignedChildIndex(int i)
void setDividerDrawable(Drawable divider)
Set a drawable to be used as a divider between items.
void setDividerPadding(int padding)
Set padding displayed on both ends of dividers.
void setGravity(int gravity)
Describes how the child views are positioned.
void setHorizontalGravity(int horizontalGravity)
void setMeasureWithLargestChildEnabled(boolean enabled)
When set to true, all children with a weight will be considered having the minimum size of the largest child.
void setOrientation(int orientation)
Should the layout be a column or a row.
void setShowDividers(int showDividers)
Set how dividers should be shown between items in this layout
void setVerticalGravity(int verticalGravity)
void setWeightSum(float weightSum)
Defines the desired weights sum.
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)
LinearLayout.LayoutParams generateDefaultLayoutParams()
Returns a set of layout parameters with a width of MATCH_PARENT and a height of WRAP_CONTENT when the layout's orientation is VERTICAL.
LinearLayout.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p)
Returns a safe set of layout parameters based on the supplied layout params.
void onDraw(Canvas canvas)
Implement this to do your drawing.
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.

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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:baselineAligned

When set to false, prevents the layout from aligning its children's baselines. This attribute is particularly useful when the children use different values for gravity. The default value is true.

Must be a boolean value, either "true" or "false".

This may also be a reference to a resource (in the form "@[package:]type:name") or theme attribute (in the form "?[package:][type:]name") containing a value of this type.

This corresponds to the global attribute resource symbol baselineAligned.

Related Methods

android:baselineAlignedChildIndex

When a linear layout is part of another layout that is baseline aligned, it can specify which of its children to baseline align to (that is, which child TextView).

Must be an integer value, such as "100".

This may also be a reference to a resource (in the form "@[package:]type:name") or theme attribute (in the form "?[package:][type:]name") containing a value of this type.

This corresponds to the global attribute resource symbol baselineAlignedChildIndex.

android:divider

Drawable to use as a vertical divider between buttons.

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

May be a color value, in the form of "#rgb", "#argb", "#rrggbb", or "#aarrggbb".

This corresponds to the global attribute resource symbol divider.

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:measureWithLargestChild

When set to true, all children with a weight will be considered having the minimum size of the largest child. If false, all children are measured normally.

Must be a boolean value, either "true" or "false".

This may also be a reference to a resource (in the form "@[package:]type:name") or theme attribute (in the form "?[package:][type:]name") containing a value of this type.

This corresponds to the global attribute resource symbol measureWithLargestChild.

android:orientation

Should the layout be a column or a row? Use "horizontal" for a row, "vertical" for a column. The default is horizontal.

Must be one of the following constant values.

ConstantValueDescription
horizontal0 Defines an horizontal widget.
vertical1 Defines a vertical widget.

This corresponds to the global attribute resource symbol orientation.

Related Methods

android:weightSum

Defines the maximum weight sum. If unspecified, the sum is computed by adding the layout_weight of all of the children. This can be used for instance to give a single child 50% of the total available space by giving it a layout_weight of 0.5 and setting the weightSum to 1.0.

Must be a floating point value, such as "1.2".

This may also be a reference to a resource (in the form "@[package:]type:name") or theme attribute (in the form "?[package:][type:]name") containing a value of this type.

This corresponds to the global attribute resource symbol weightSum.

Related Methods

Constants

public static final int HORIZONTAL

Added in API level 1

Constant Value: 0 (0x00000000)

public static final int SHOW_DIVIDER_BEGINNING

Added in API level 11

Show a divider at the beginning of the group.

Constant Value: 1 (0x00000001)

public static final int SHOW_DIVIDER_END

Added in API level 11

Show a divider at the end of the group.

Constant Value: 4 (0x00000004)

public static final int SHOW_DIVIDER_MIDDLE

Added in API level 11

Show dividers between each item in the group.

Constant Value: 2 (0x00000002)

public static final int SHOW_DIVIDER_NONE

Added in API level 11

Don't show any dividers.

Constant Value: 0 (0x00000000)

public static final int VERTICAL

Added in API level 1

Constant Value: 1 (0x00000001)

Public Constructors

public LinearLayout (Context context)

Added in API level 1

public LinearLayout (Context context, AttributeSet attrs)

Added in API level 1

public LinearLayout (Context context, AttributeSet attrs, int defStyleAttr)

Added in API level 11

public LinearLayout (Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)

Added in API level 21

Public Methods

public LinearLayout.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 getBaselineAlignedChildIndex ()

Added in API level 1

Returns
  • The index of the child that will be used if this layout is part of a larger layout that is baseline aligned, or -1 if none has been set.

public Drawable getDividerDrawable ()

Added in API level 16

Related XML Attributes
Returns
  • the divider Drawable that will divide each item.

public int getDividerPadding ()

Added in API level 14

Get the padding size used to inset dividers in pixels

public int getOrientation ()

Added in API level 1

Returns the current orientation.

Returns

public int getShowDividers ()

Added in API level 11

Returns
  • A flag set indicating how dividers should be shown around items.

public float getWeightSum ()

Added in API level 1

Returns the desired weights sum.

Returns
  • A number greater than 0.0f if the weight sum is defined, or a number lower than or equals to 0.0f if not weight sum is to be used.

public boolean isBaselineAligned ()

Added in API level 1

Indicates whether widgets contained within this layout are aligned on their baseline or not.

Returns
  • true when widgets are baseline-aligned, false otherwise

public boolean isMeasureWithLargestChildEnabled ()

Added in API level 11

When true, all children with a weight will be considered having the minimum size of the largest child. If false, all children are measured normally.

Related XML Attributes
Returns
  • True to measure children with a weight using the minimum size of the largest child, false otherwise.

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 setBaselineAligned (boolean baselineAligned)

Added in API level 1

Defines whether widgets contained in this layout are baseline-aligned or not.

Related XML Attributes
Parameters
baselineAligned true to align widgets on their baseline, false otherwise

public void setBaselineAlignedChildIndex (int i)

Added in API level 1

Related XML Attributes
Parameters
i The index of the child that will be used if this layout is part of a larger layout that is baseline aligned.

public void setDividerDrawable (Drawable divider)

Added in API level 11

Set a drawable to be used as a divider between items.

Related XML Attributes
Parameters
divider Drawable that will divide each item.

public void setDividerPadding (int padding)

Added in API level 14

Set padding displayed on both ends of dividers.

Parameters
padding Padding value in pixels that will be applied to each end

public void setGravity (int gravity)

Added in API level 1

Describes how the child views are positioned. Defaults to GRAVITY_TOP. If this layout has a VERTICAL orientation, this controls where all the child views are placed if there is extra vertical space. If this layout has a HORIZONTAL orientation, this controls the alignment of the children.

Related XML Attributes
Parameters
gravity See Gravity

public void setHorizontalGravity (int horizontalGravity)

Added in API level 1

public void setMeasureWithLargestChildEnabled (boolean enabled)

Added in API level 11

When set to true, all children with a weight will be considered having the minimum size of the largest child. If false, all children are measured normally. Disabled by default.

Related XML Attributes
Parameters
enabled True to measure children with a weight using the minimum size of the largest child, false otherwise.

public void setOrientation (int orientation)

Added in API level 1

Should the layout be a column or a row.

Related XML Attributes
Parameters
orientation Pass HORIZONTAL or VERTICAL. Default value is HORIZONTAL.

public void setShowDividers (int showDividers)

Added in API level 11

Set how dividers should be shown between items in this layout

Parameters
showDividers One or more of SHOW_DIVIDER_BEGINNING, SHOW_DIVIDER_MIDDLE, or SHOW_DIVIDER_END, or SHOW_DIVIDER_NONE to show no dividers.

public void setVerticalGravity (int verticalGravity)

Added in API level 1

public void setWeightSum (float weightSum)

Added in API level 1

Defines the desired weights sum. If unspecified the weights sum is computed at layout time by adding the layout_weight of each child. This can be used for instance to give a single child 50% of the total available space by giving it a layout_weight of 0.5 and setting the weightSum to 1.0.

Parameters
weightSum a number greater than 0.0f, or a number lower than or equals to 0.0f if the weight sum should be computed from the children's layout_weight

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 LinearLayout.LayoutParams generateDefaultLayoutParams ()

Added in API level 1

Returns a set of layout parameters with a width of MATCH_PARENT and a height of WRAP_CONTENT when the layout's orientation is VERTICAL. When the orientation is HORIZONTAL, the width is set to WRAP_CONTENT and the height to WRAP_CONTENT.

Returns
  • a set of default layout parameters or null

protected LinearLayout.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 onDraw (Canvas canvas)

Added in API level 1

Implement this to do your drawing.

Parameters
canvas the canvas on which the background will be drawn

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.