Execute java instance method via terminal

I have an instance. Basic structure is ;

class Instance{

    public void load(){
        ...
    }

    public boolean execute(){
        ...
        return true;
    }

}

As normally we can execute this instance in static void main(String args[]) but how can we execute this instance -> load() -> execute() from terminal or compiled file .class is called within a main method than using reflection to execute defined methods.
Because this instance acts like a script on out project, but we do not define main function into class.

Anyone helps?