alignParentBottom

alignParentBottom is a layout attribute commonly used in Android development. It is a boolean value that, when set to true for a view, instructs the Android layout system to position that view at the bottom edge of its parent container. This attribute is typically used within a RelativeLayout, which allows for flexible positioning of child views relative to each other and the parent.

When a view has alignParentBottom set to true, it will be aligned with the bottom boundary of its parent layout. If other sibling views are also present, their positions will be adjusted accordingly. This attribute is fundamental for creating responsive and structured user interfaces in Android applications, ensuring that certain elements consistently occupy the bottom space regardless of screen size or orientation.

For example, in a RelativeLayout, if you have a button that you want to always appear at the very bottom of the screen, you would set its android:layout_alignParentBottom attribute to "true". This simplifies the process of creating layouts where specific components need to maintain a fixed position at the lower edge of the screen, such as navigation bars or action buttons. Understanding and utilizing alignParentBottom is a key aspect of efficient Android UI design.