What is the use of tools in Android?

In Android development, the tools namespace is a special tool used to assist developers in layout design and preview. When using the tools namespace, properties are not applied to the actual running code but only work during the development stage. This helps to improve development efficiency and the accuracy of preview views.

Common uses include:

1. tools:showIn attribute: used to display or hide a layout element in the design view.
2. tools:listitem attribute: used to display the style of a single list item in RecyclerView or ListView.
3. The tools:context attribute is used to simulate the context of an Activity in the design view, allowing for the simulation of the Activity’s state in the preview layout.
4. TargetApi attribute: specifies the behavior of the application on a specific API level in order to provide a more accurate preview in the preview view.

In general, the tools namespace provides a convenient way to simulate data and environments, allowing for a more accurate preview of UI effects when designing layouts.