How to call from an activity to a method of another class

To call a method from another class in a Activity, the method must first be defined with the modifier public, which is correct:

public class DecisorCoordenadas {
   public DecisorCoordenadas(Context contexto, Coordinador coordinador) {
   ...
   ...

If we review the parameters that you need, they are the one Contextoof the Activity, although the one of the application can be used which is lighter (Check how it would be used since in some cases you require the one of the Activityfor example when creating a dialog within the class) , and an object of typeCoordinador

As the method DecisorCoordenadas()is not defined as staticthe class has to be instantiated to call the method from the Activity.

In the case of the method described in your question, this method is actually the constructor used to initialize the class :

DecisorCoordenadas decisorCoordenadas = new DecisorCoordenadas(this, myObjetoCoordinador);

either

DecisorCoordenadas decisorCoordenadas = new DecisorCoordenadas(getApplicactionContext(), myObjetoCoordinador);

I would like to know how I could execute a method

public void resetInfo_Coordenadas(){  

of my java class from activity.

I imagine this method is inside the class DecisorCoordenadas, so it can be called in this way from the Activity, first we instantiate the class since the method is not defined as staticand by having the instance we can call the method:

DecisorCoordenadas decisorCoordenadas = new DecisorCoordenadas(this, myObjetoCoordinador);
decisorCoordenadas.resetInfo_Coordenadas(); 

A slightly similar question is asked in the Java Tag in the case of Android it would be similar.

You have to create an object of the DecisorCoordenadas class by doing a

DecisorCoordenadas dc = new DecisorCoordenadas(this, myCoordinador);

And then you can call the method using the previously created object.

dc.resetInfo_Coordenadas();

Try instantiating the class from your Activitylike this:

DecisorCoordenadas dc = new DecisorCoordenadas(this, coordinador);
dc.resetInfo_Coordenadas();

You can create an instance of your class or make your method static:

public static void resetInfo_Coordenadas(){ ... }

In your main class you would access with your class name (dot) and method name:

DecisorCoordenadas.resetInfo_Coordenadas();