In an android project, I had the following line in main_activity.xml without giving any error:
tools:context="com.example.alumno.prueba_2.Launch" (activity main.xml, carpeta layout dentro de res)
but now it does (unresolve launch class) without having changed anything for it. Why is it?
Now you have an error because the name of the class changed or the package that contains it.
tools:context="com.example.alumno.prueba_2.Launch"
Ensure the name of the class is correct as well as the package that contains it.
Ensure that the class is the one that loads the layout by setContentView() .
As another option, you can also delete the line to avoid the problem.
Try the following:
tools:context="ruta_de_tu_actividad_a_la_que_hace_referencia_al_layout"
Example:
tools:context="com.example.alumno.prueba_2.LaunchActivity"
Greetings.