Adding a login screen
Before creating Android views, it is important to know the different layouts or view group types available in Android. iOS does not have an equivalent for some of these because iOS has a smaller variation of screen sizes on its devices. Since Android has virtually infinite screen sizes and densities, the Android SDK has a lot of built-in support for auto-sizing and layout for views.
The following are the common types of layouts:
ViewGroup: This is the base class for a view that contains a collection of child views. You normally won't use this class directly.LinearLayout: This is a layout that positions its child views in rows or columns (but not both). You can also set weights on each child, to have them span different percentages of the available space.RelativeLayout: This is a layout that gives much more flexibility on the position of its children. You can position child views relative to each other so that they are above, below, to the left, or to the right of one...
