LevelListDrawable

LevelListDrawable is a drawable in the Android operating system that allows you to display different drawables based on a specific level. This level is an integer value that you set programmatically or through XML. The LevelListDrawable contains a list of items, where each item associates a drawable with a specific level or a range of levels. When the level of the LevelListDrawable changes, it selects and displays the corresponding drawable from its list.

You can define a LevelListDrawable in an XML resource file located in the res/drawable directory. The root element is a LevelListDrawable, and it contains one or more item elements. Each item has a drawable attribute specifying the drawable to be displayed and an android:minLevel and/or android:maxLevel attribute to define the level range for that drawable. If only one level is specified, it typically uses android:maxLevel to denote the exact level at which the drawable should be shown.

Programmatically, you can create a LevelListDrawable and add items to it using the addLevel method. This method takes an integer for the level and a Drawable object. You can then set the level of the LevelListDrawable using the setLevel(int level) method, which will cause the appropriate drawable to be displayed.

LevelListDrawable is useful for scenarios where you need to visually represent a state or progress. Examples include displaying different icons for battery levels, different images for network signal strength, or various states of a progress indicator. It provides a flexible way to manage multiple visual states associated with a numerical value without having to manually switch drawables in your code.