Promote in a group ladder

Currently I am trying to create a Permission plugin but... i have a problem:
I don't realize how to make the "Group Ladder" aka [Inheritance] promote command...

This is the code that create the "inheritance" config:

Code:

public class Inheritor implements CommandExecutor {
   
    private File hre;
    private FileConfiguration cfg;
    private RipHudRanks plugin;
    private File_Players players;
   
    public Inheritor(RipHudRanks plugin){
        this.plugin = plugin;
        this.hre = new File("plugins/RipHudRanks", "InheritanceList.yml");
        this.cfg = YamlConfiguration.loadConfiguration(this.hre);
       
        if (!this.hre.exists()){
            try{
                this.cfg.save(this.hre);
            }catch (IOException e){
                e.printStackTrace();
            }
        }
    }
    public File getGroup(){
        return this.hre;
    }
    public FileConfiguration getCfg(){
        return this.cfg;
    }
    public void saveCfg(){
        try{
            this.cfg.save(this.hre);
        }catch (IOException e){
            e.printStackTrace();
        }
    }

    @Override
    public boolean onCommand(CommandSender cs, Command cmd, String label, String[] arg) {
        if (cmd.getName().equalsIgnoreCase("inherit")){
            List<String> inh = getCfg().getStringList("Inherit." + arg[0]);
            inh.add(arg[1]);
            getCfg().set("Inheritor." + arg[0], inh);
            saveCfg();
            cs.sendMessage("Now, the group: " + arg[1] + " is inherited to group: " + arg[0]);
        }
           
       
        return true;
    }

}

Now.. I have a total of 3 configs:
player.yml *
- It store players with their
- Groups
- Permissions (separately from the group defined perms)

groups.yml
- It store groups with
- Perms
- Variables

InheritanceList.yml *
- It store groups that inherits another groups
so.. if i type /i staff admin
the group admin will be an object on the ladder "staff"
/* the group "def" was inserted there first */
It will look like that:

Code:

Inheritor:
   staff:
        - admin
        - def

Now... I have a player called "Elite" assigned to group "def" ,
How do i replace the [players.yml > Elite > Groups > "def"] with the next group in the list "staff"?

 

@TitaniuMark

If I read your question, it looks like you want to modify the config of player 'Elite'. Is that really what you want to do?

 

Yes ... I want to modify the config of player 'Elite" relyed to the "staff" ladder on Inheritance config....

 

@TitaniuMark

Ah, now I realize what you are trying to do and why.
I think you can load the list of the ranks with something like

Code:

cfg.getConfigurationSection("Inheritance").getStringList("staff");

Then use the indexOf method of that string list with the current rank. If it is 0, player already has max rank. If not, the new rank should be list.get(index - 1);

Then change the value in your players config and save your players config.