Stuck on using methods from api

Well im making a api, and i have the instance on it, i also have a testmethod:

public int testmethod(){
return 1;
}
But when i call the api from another plugin,

Api a = new Api(); (api is the name of the api i made) // this works fine.
But when i refet to a. it doesnt show the method in it, like it doesnt even exist...
What should i do to make methods acessable?
Here the whole class:

Code:java

public class GeneralAPI implements Listener {
 
    private static GeneralAPI instance;
    private Plugin plugin;
 
    public static GeneralAPI getGeneralApi() {
        if (instance == null) instance = new GeneralAPI();
        return instance;
    }
 
    public void registerEvents(Listener listener, Plugin plugin) {
        this.plugin = plugin;
        Bukkit.getServer().getPluginManager().registerEvents(listener, plugin);
        Bukkit.getServer().getPluginManager().registerEvents(this, plugin);
 
    }
 
    public static int adone(){
        return 1;
    }
 
 
}