Android-Whatisthedifferencebetweenthesethreexmlfiles?

What is the difference between these three xml files in android?

xml file with selector as root element

    
        
            
            ...
        
    

xml file with shape as root element

    
    ...

xml file with layer-list as root element

    
        
            
            ...
        
    
    
        
            
            ...
        
    

Which one is used in which case. A little examples will be more appreciated. Thanks!!!

Layer List
From docs:
A Drawable that manages an array of other Drawables. These are drawn in array order, so the element with the largest index is be drawn on top. Creates a LayerDrawable.

This is used when you want to combine multiple drawables into one, for example you could use it to add a background to an icon.

Selector (StateList)
From docs:
A StateListDrawable is a drawable object defined in XML that uses a several different images to represent the same graphic, depending on the state of the object. For example, a Button widget can exist in one of several different states (pressed, focused, or neither) and, using a state list drawable, you can provide a different background image for each state.

It can used to show different drawables in different conditions.

Shape
From docs:
An XML file that defines a geometric shape, including colors and gradients. Creates a GradientDrawable.

This should be used when you want to show a single shape. It can be used inside a LayerList to add a shape to an image or it can be used with a selector to switch between shapes as well.

Fun Part(hopefully)
All 3 of these represent drawables so you can combine these to meet your needs. For example I could have selector as root element, which contains LayerList and each layer list can have shapes. When working with these dynamically, all 3 are subclasses of Drawable class.

Check out documentation for more information: https://developer.android.com/guide/topics/resources/drawable-resource