What does android layout weight mean

Question

I don t understand how to use this attribute  Can anyone tell me more about it

User · Answer

http   developer android com guide topics ui layout-objects html linearlayout  layout weight defines how much space the control must obtain respectively to other controls

User · Answer

Adding android autoSizeTextType  uniform  will resize the text for you automatically

User · Answer

layout weight tells Android how to distribute your Views in a LinearLayout  Android then first calculates the total proportion required for all Views that have a weight specified and places each View according to what fraction of the screen it has specified it needs  In the following example  Android sees that the TextViews have a layout weight of 0  this is the default  and the EditTexts have a layout weight of 2 each  while the Button has a weight of 1  So Android allocates  just enough  space to display tvUsername and tvPassword and then divides the remainder of the screen width into 5 equal parts  two of which are allocated to etUsername  two to etPassword and the last part to bLogin    lt LinearLayout android orientation  horizontal      gt        lt TextView android id    id tvUsername       android text  Username       android layout width  wrap content        gt        lt EditText android id    id etUsername      android layout width  0dp      android layout weight  2        gt        lt TextView android id    id tvPassword      android text  Password      android layout width  wrap content    gt        lt EditText android id    id etPassword      android layout width  0dp      android layout weight  2        gt        lt Button android id    id bLogin      android layout width  0dp      android layout weight  1      android text  Login       gt    lt  LinearLayout gt    It looks like   and

User · Answer

In a nutshell  layout weight specifies how much of the extra space in the layout to be allocated to the View  LinearLayout supports assigning a weight to individual children  This attribute assigns an  quot importance quot  value to a view  and allows it to expand to fill any remaining space in the parent view  Views  default weight is zero  Calculation to assign any remaining space between child In general  the formula is   space assigned to child    child s individual weight     sum of weight of every child in Linear Layout   Example 1 If there are three text boxes and two of them declare a weight of 1  while the third one is given no weight  0   then remaining space is assigned as follows   1st text box   1  1 1 0  2nd text box   1  1 1 0  3rd text box   0  1 1 0   Example 2 Let s say we have a text label and two text edit elements in a horizontal row  The label has no layout weight specified  so it takes up the minimum space required to render  If the layout weight of each of the two text edit elements is set to 1  the remaining width in the parent layout will be split equally between them  because we claim they are equally important   Calculation   1st label   0  0 1 1  2nd text box   1  0 1 1  3rd text box   1  0 1 1   If  instead  the first one text box has a layout weight of 1  and the second text box has a layout weight of 2  then one third of the remaining space will be given to the first  and two thirds to the second  because we claim the second one is more important   Calculation   1st label   0  0 1 2  2nd text box   1  0 1 2  3rd text box   2  0 1 2    Source article

User · Answer

As the name suggests  Layout weight specifies what amount or percentage of space a particular field or widget should occupy the screen space  If we specify weight in horizontal orientation  then we must specify layout width   0px  Similarly  If we specify weight in vertical orientation  then we must specify layout height   0px

User · Answer

With layout weight you can specify a size ratio between multiple views  E g  you have a MapView and a table which should show some additional information to the map  The map should use 3 4 of the screen and table should use 1 4 of the screen  Then you will set the layout weight of the map to 3 and the layout weight of the table to 1    To get it work you also have to set the height or width  depending on your orientation  to 0px

User · Answer

Please look at the weightSum of LinearLayout and the layout weight of each View  android weightSum  4  android layout weight  2  android layout weight  2  Their layout height are both 0px  but I am not sure it is relevan   lt  xml version  1 0  encoding  utf-8   gt   lt LinearLayout xmlns android  http   schemas android com apk res android  xmlns tools  http   schemas android com tools  android orientation  vertical  android layout width  match parent  android layout height  match parent  android weightSum  4  gt    lt fragment android name  com example SettingFragment      android id    id settingFragment      android layout width  match parent      android layout height  0px      android layout weight  2        gt    lt Button     android id    id dummy button      android layout width  match parent      android layout height  0px      android layout weight  2      android text  DUMMY        gt   lt  LinearLayout gt

User · Answer

Think it that way  will be simpler  If you have 3 buttons and their weights are 1 3 1 accordingly  it will work like table in HTML  Provide 5 portions for that line  1 portion for button 1  3 portion for button 2 and 1 portion for button 1  Regard

User · Answer

If there are multiple views spanning a LinearLayout  then layout weight gives them each a proportional size  A view with a bigger layout weight value  weighs  more  so it gets a bigger space   Here is an image to make things more clear     Theory  The term layout weight is related to the concept of weighted average in math  It is like in a college class where homework is worth 30   attendance is worth 10   the midterm is worth 20   and the final is worth 40   Your scores for those parts  when weighted together  give you your total grade     It is the same for layout weight  The Views in a horizontal LinearLayout can each take up a certain percentage of the total width   Or a percentage of the height for a vertical LinearLayout    The Layout  The LinearLayout that you use will look something like this    lt LinearLayout     android layout width  match parent      android layout height  wrap content      android orientation  horizontal  gt        lt  -- list of subviews -- gt    lt  LinearLayout gt    Note that you must use layout width  match parent  for the LinearLayout  If you use wrap content  then it won t work  Also note that layout weight does not work for the views in RelativeLayouts  see here and here for SO answers dealing with this issue    The Views  Each view in a horizontal LinearLayout looks something like this    lt Button     android layout width  0dp      android layout height  wrap content      android layout weight  1    gt    Note that you need to use layout width  0dp  together with layout weight  1   Forgetting this causes many new users problems   See this article for different results you can get by not setting the width to 0   If your views are in a vertical LinearLayout then you would use layout height  0dp   of course   In the Button example above I set the weight to 1  but you can use any number  It is only the total that matters  You can see in the three rows of buttons in the first image that I posted  the numbers are all different  but since the proportions are the same  the weighted widths don t change in each row  Some people like to use decimal numbers that have a sum of 1 so that in a complex layout it is clear what the weight of each part is   One final note  If you have lots of nested layouts that use layout weight  it can be bad for performance   Extra  Here is the xml layout for the top image    lt  xml version  1 0  encoding  utf-8   gt   lt LinearLayout xmlns android  http   schemas android com apk res android      android orientation  vertical      android layout width  match parent      android layout height  match parent  gt        lt TextView         android layout width  wrap content          android layout height  wrap content          android text  android layout weight           android textSize  24sp    gt        lt LinearLayout         android layout width  match parent          android layout height  wrap content          android orientation  horizontal  gt            lt Button             android layout width  0dp              android layout height  wrap content              android layout weight  1              android text  1    gt            lt Button             android layout width  0dp              android layout height  wrap content              android layout weight  2              android text  2    gt            lt Button             android layout width  0dp              android layout height  wrap content              android layout weight  1              android text  1    gt        lt  LinearLayout gt        lt TextView         android layout width  wrap content          android layout height  wrap content          android text  android layout weight           android textSize  24sp    gt        lt LinearLayout         android layout width  match parent          android layout height  wrap content          android orientation  horizontal  gt            lt Button             android layout width  0dp              android layout height  wrap content              android layout weight  10              android text  10    gt            lt Button             android layout width  0dp              android layout height  wrap content              android layout weight  20              android text  20    gt            lt Button             android layout width  0dp              android layout height  wrap content              android layout weight  10              android text  10    gt        lt  LinearLayout gt        lt TextView         android layout width  wrap content          android layout height  wrap content          android text  android layout weight           android textSize  24sp    gt        lt LinearLayout         android layout width  match parent          android layout height  wrap content          android orientation  horizontal  gt            lt Button             android layout width  0dp              android layout height  wrap content              android layout weight   25              android text   25    gt            lt Button             android layout width  0dp              android layout height  wrap content              android layout weight   50              android text   50    gt            lt Button             android layout width  0dp              android layout height  wrap content              android layout weight   25              android text   25    gt        lt  LinearLayout gt    lt  LinearLayout gt

User · Answer

adding to the other answers  the most important thing to get this to work is to set the layout width  or height  to 0px  android layout width  0px    otherwise you will see garbage

User · Answer

Combining both answers from  Flo  amp  rptwsthi and roetzi   Do remember to change your layout width 0dp px  else the layout weight behaviour will act reversely with biggest number occupied the smallest space and lowest number occupied the biggest space   Besides  some weights combination will caused some layout cannot be shown  since it over occupied the space    Beware of this

User · Answer

For additional     For vertical orientation  don t forget set height to 0dp  android layout height  0dp    For horizontal orientation  don t forget set width to 0dp  android layout width  0dp

User · Answer

one of the best explanations for me was this one  from the Android tutorial  look for step 7    layout weight is used in LinearLayouts to assign  quot importance quot  to Views within the layout  All Views have a default layout weight of zero  meaning they take up only as much room on the screen as they need to be displayed  Assigning a value higher than zero will split up the rest of the available space in the parent View  according to the value of each View s layout weight and its ratio to the overall layout weight specified in the current layout for this and other View elements  To give an example  let s say we have a text label and two text edit elements in a horizontal row  The label has no layout weight specified  so it takes up the minimum space required to render  If the layout weight of each of the two text edit elements is set to 1  the remaining width in the parent layout will be split equally between them  because we claim they are equally important   If the first one has a layout weight of 1 and the second has a layout weight of 2  then one third of the remaining space will be given to the first  and two thirds to the second  because we claim the second one is more important

[android] What does android:layout_weight mean?

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