what is a adt application
Android Developer Tools (ADT) is a plugin for Eclipse that provides GUI-based access to many of the command-line Android SDK tools. As with ADT, support for the Ant tool for building from the command line has ended. Gradle is now the supported method of building Android apps.
In computer science, an abstract data type (ADT) is a mathematical model for data types where a data type is defined by its behavior (semantics) from the point of view of a user of the data, specifically in terms of possible values, possible operations on data of this type, and the behavior of these operations.