附加:

对于垂直方向，不要忘记设置高度为0dp

android:layout_height="0dp"

对于水平方向，不要忘记设置宽度为0dp

android:layout_width="0dp"

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).

添加android:autoSizeTextType="uniform"将自动调整文本大小

顾名思义，布局权重指定了特定字段或小部件应该占据屏幕空间的数量或百分比。 如果我们在水平方向上指定权重，那么我们必须指定layout_width = 0px。 类似地，如果我们在垂直方向上指定权重，那么我们必须指定layout_height = 0px。

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。

结合以下两个答案

Flo, rptwsthi和roetzi，

记住要改变你的layout_width=0dp/px，否则layout_weight行为将会相反，最大的数字占据最小的空间，最小的数字占据最大的空间。

此外，一些权重组合会导致一些布局无法显示(因为它过度占用空间)。

当心这一点。