对我来说最好的解释之一是这个(来自Android教程，请参阅第7步):

layout_weight is used in LinearLayouts to assign "importance" 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).

http://developer.android.com/guide/topics/ui/layout-objects.html#linearlayout

Layout_weight定义了控件相对于其他控件必须获得的空间大小。

简而言之，layout_weight指定了布局中要分配给View的额外空间的多少。

线性布局支持为各个子节点分配权重。此属性为视图分配了一个“重要性”值，并允许它展开以填充父视图中的任何剩余空间。视图的默认权重为0。

计算子节点之间的剩余空间

一般情况下，公式为:

分配给孩子的空间=(孩子的个人体重)/(线性布局中每个孩子的体重之和)

示例1

如果有三个文本框，其中两个声明权重为1，而第三个文本框没有权重(0)，那么剩余空间的分配如下:

第一个文本框= 1/(1+1+0) 第二个文本框= 1/(1+1+0) 第三个文本框= 0/(1+1+0)

示例2

假设在水平行中有一个文本标签和两个文本编辑元素。标签没有指定layout_weight，因此它占用呈现所需的最小空间。如果这两个文本编辑元素的layout_weight都设置为1，父布局中的剩余宽度将在它们之间平均分配(因为我们声称它们同样重要)。

计算:

第一个标签= 0/(0+1+1) 第二个文本框= 1/(0+1+1) 第三个文本框= 1/(0+1+1)

如果第一个文本框的layout_weight为1，第二个文本框的layout_weight为2，那么剩余空间的三分之一将给第一个文本框，三分之二给第二个文本框(因为我们声称第二个文本框更重要)。

计算:

第一个标签= 0/(0+1+2) 第二个文本框= 1/(0+1+2) 第三个文本框= 2/(0+1+2)

文章来源

使用layout_weight，你可以指定多个视图之间的大小比例。例如，你有一个MapView和一个表，它应该显示一些额外的信息到地图。地图应该使用屏幕的3/4，表格应该使用屏幕的1/4。然后将映射的layout_weight设置为3，将表的layout_weight设置为1。

为了让它工作，你还必须设置高度或宽度(取决于你的方向)为0px。

对我来说最好的解释之一是这个(来自Android教程，请参阅第7步):

layout_weight is used in LinearLayouts to assign "importance" 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).

那样想的话，会简单些

如果你有3个按钮，它们的权重分别为1,3,1，它将像HTML中的表格一样工作

为这一行提供5份:1份用于按钮1,3份用于按钮2,1份用于按钮1

方面,