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LinearLayout

public class LinearLayout
extends ViewGroup

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


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

android:baselineAligned When set to false, prevents the layout from aligning its children's baselines. 
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). 
android:divider Drawable to use as a vertical divider between buttons. 
android:gravity Specifies how an object should position its content, on both the X and Y axes, within its own bounds. 
android:measureWithLargestChild When set to true, all children with a weight will be considered having the minimum size of the largest child. 
android:orientation 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. 

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

Inherited constants

From class android.view.ViewGroup
From class android.view.View

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.

CharSequence getAccessibilityClassName()

Return the class name of this object to be used for accessibility purposes.

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 getGravity()

Returns the current gravity.

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 onRtlPropertiesChanged(int layoutDirection)

Called when any RTL property (layout direction or text direction or text alignment) has been changed.

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 lp)

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.

Inherited methods

From class android.view.ViewGroup
From class android.view.View
From class java.lang.Object
From interface android.view.ViewParent
From interface android.view.ViewManager
From interface android.graphics.drawable.Drawable.Callback
From interface android.view.KeyEvent.Callback
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.

Related methods:

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.

Related methods:

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.

Related methods:

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.

Constants

HORIZONTAL

Added in API level 1
int HORIZONTAL

Constant Value: 0 (0x00000000)

SHOW_DIVIDER_BEGINNING

Added in API level 11
int SHOW_DIVIDER_BEGINNING

Show a divider at the beginning of the group.

Constant Value: 1 (0x00000001)

SHOW_DIVIDER_END

Added in API level 11
int SHOW_DIVIDER_END

Show a divider at the end of the group.

Constant Value: 4 (0x00000004)

SHOW_DIVIDER_MIDDLE

Added in API level 11
int SHOW_DIVIDER_MIDDLE

Show dividers between each item in the group.

Constant Value: 2 (0x00000002)

SHOW_DIVIDER_NONE

Added in API level 11
int SHOW_DIVIDER_NONE

Don't show any dividers.

Constant Value: 0 (0x00000000)

VERTICAL

Added in API level 1
int VERTICAL

Constant Value: 1 (0x00000001)

Public constructors

LinearLayout

Added in API level 1
LinearLayout (Context context)

Parameters
context Context

LinearLayout

Added in API level 1
LinearLayout (Context context, 
                AttributeSet attrs)

Parameters
context Context
attrs AttributeSet

LinearLayout

Added in API level 11
LinearLayout (Context context, 
                AttributeSet attrs, 
                int defStyleAttr)

Parameters
context Context
attrs AttributeSet
defStyleAttr int

LinearLayout

Added in API level 21
LinearLayout (Context context, 
                AttributeSet attrs, 
                int defStyleAttr, 
                int defStyleRes)

Parameters
context Context
attrs AttributeSet
defStyleAttr int
defStyleRes int

Public methods

generateLayoutParams

Added in API level 1
LinearLayout.LayoutParams generateLayoutParams (AttributeSet attrs)

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

Parameters
attrs AttributeSet: the attributes to build the layout parameters from
Returns
LinearLayout.LayoutParams an instance of ViewGroup.LayoutParams or one of its descendants

getAccessibilityClassName

Added in API level 23
CharSequence getAccessibilityClassName ()

Return the class name of this object to be used for accessibility purposes. Subclasses should only override this if they are implementing something that should be seen as a completely new class of view when used by accessibility, unrelated to the class it is deriving from. This is used to fill in AccessibilityNodeInfo.setClassName.

Returns
CharSequence

getBaseline

Added in API level 1
int getBaseline ()

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

getBaselineAlignedChildIndex

Added in API level 1
int getBaselineAlignedChildIndex ()

Returns
int 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.

getDividerDrawable

Added in API level 16
Drawable getDividerDrawable ()

Related XML Attributes:

Returns
Drawable the divider Drawable that will divide each item.

See also:

getDividerPadding

Added in API level 14
int getDividerPadding ()

Get the padding size used to inset dividers in pixels

Returns
int

See also:

getGravity

Added in API level 24
int getGravity ()

Returns the current gravity. See Gravity

Returns
int the current gravity.

See also:

getOrientation

Added in API level 1
int getOrientation ()

Returns the current orientation.

Returns
int either HORIZONTAL or VERTICAL

getShowDividers

Added in API level 11
int getShowDividers ()

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

See also:

getWeightSum

Added in API level 1
float getWeightSum ()

Returns the desired weights sum.

Returns
float 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.

isBaselineAligned

Added in API level 1
boolean isBaselineAligned ()

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

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

isMeasureWithLargestChildEnabled

Added in API level 11
boolean isMeasureWithLargestChildEnabled ()

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
boolean True to measure children with a weight using the minimum size of the largest child, false otherwise.

onRtlPropertiesChanged

Added in API level 17
void onRtlPropertiesChanged (int layoutDirection)

Called when any RTL property (layout direction or text direction or text alignment) has been changed. Subclasses need to override this method to take care of cached information that depends on the resolved layout direction, or to inform child views that inherit their layout direction. The default implementation does nothing.

Parameters
layoutDirection int: the direction of the layout

setBaselineAligned

Added in API level 1
void setBaselineAligned (boolean baselineAligned)

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

Related XML Attributes:

Parameters
baselineAligned boolean: true to align widgets on their baseline, false otherwise

setBaselineAlignedChildIndex

Added in API level 1
void setBaselineAlignedChildIndex (int i)

Related XML Attributes:

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

setDividerDrawable

Added in API level 11
void setDividerDrawable (Drawable divider)

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

Related XML Attributes:

Parameters
divider Drawable: Drawable that will divide each item.

See also:

setDividerPadding

Added in API level 14
void setDividerPadding (int padding)

Set padding displayed on both ends of dividers.

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

See also:

setGravity

Added in API level 1
void setGravity (int gravity)

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 int: See Gravity

setHorizontalGravity

Added in API level 1
void setHorizontalGravity (int horizontalGravity)

Parameters
horizontalGravity int

setMeasureWithLargestChildEnabled

Added in API level 11
void setMeasureWithLargestChildEnabled (boolean enabled)

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 boolean: True to measure children with a weight using the minimum size of the largest child, false otherwise.

setOrientation

Added in API level 1
void setOrientation (int orientation)

Should the layout be a column or a row.

Related XML Attributes:

Parameters
orientation int: Pass HORIZONTAL or VERTICAL. Default value is HORIZONTAL.

setShowDividers

Added in API level 11
void setShowDividers (int showDividers)

Set how dividers should be shown between items in this layout

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

setVerticalGravity

Added in API level 1
void setVerticalGravity (int verticalGravity)

Parameters
verticalGravity int

setWeightSum

Added in API level 1
void setWeightSum (float weightSum)

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 float: 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

shouldDelayChildPressedState

Added in API level 14
boolean shouldDelayChildPressedState ()

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.

Returns
boolean

Protected methods

checkLayoutParams

Added in API level 1
boolean checkLayoutParams (ViewGroup.LayoutParams p)

Parameters
p ViewGroup.LayoutParams
Returns
boolean

generateDefaultLayoutParams

Added in API level 1
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. When the orientation is HORIZONTAL, the width is set to WRAP_CONTENT and the height to WRAP_CONTENT.

Returns
LinearLayout.LayoutParams a set of default layout parameters or null

generateLayoutParams

Added in API level 1
LinearLayout.LayoutParams generateLayoutParams (ViewGroup.LayoutParams lp)

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
lp ViewGroup.LayoutParams: The layout parameters to convert into a suitable set of layout parameters for this ViewGroup.
Returns
LinearLayout.LayoutParams an instance of ViewGroup.LayoutParams or one of its descendants

onDraw

Added in API level 1
void onDraw (Canvas canvas)

Implement this to do your drawing.

Parameters
canvas Canvas: the canvas on which the background will be drawn

onLayout

Added in API level 1
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. Derived classes with children should override this method and call layout on each of their children.

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

onMeasure

Added in API level 1
void onMeasure (int widthMeasureSpec, 
                int heightMeasureSpec)

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 overridden 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 int: horizontal space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec.
heightMeasureSpec int: vertical space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec.
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