Chest refill every X minutes within area

The title pretty much says it all, i want to make a plugin that refills all chests within a certain area(my arena) every X minutes. The reason i made this thread is because i don't know where i should start and also i have tried searching about this for the last 1-2 hours and couldn't find anything that helped me get started with this. I tried searching how to make a runnable but all the answers was this:

Code:

Bukkit.getScheduler().scheduleSyncRepeatingTask(this, new Runnable() {
@Override
public void run() {
// Do something
}
}, 0L, 20L);

But whenever i tried this, the "Bukkit." came with this error:
"Multiple markers at this line
- Syntax error, insert ";" to complete MethodDeclaration
- Syntax error, insert "Identifier (" to complete
MethodHeaderName
- Syntax error, insert ")" to complete MethodDeclaration
- Syntax error, insert "}" to complete ClassBody"
And i don't know why i can't use "Bukkit.", i tried "this.", "plugin." and "plugin.getServer()." aswell but they all came with errors, i just want to create a class with the runnable like this:

Code:

public class ClassName {
  
    private Main plugin;
  
    public ClassName(Main plugin) {
        this.plugin = plugin;
    }
  
    Bukkit.getScheduler().scheduleSyncRepeatingTask(plugin, new Runnable() {
        @Override
        public void run() {
            // Do something
        }
    }, 0L, 20L);
}

The error is probably pretty obvious but i can't find it or anything about it. :/
Anyway, how would i make all chests within a certain area refill every X minutes?

 

@timtower But what method should i put it in? Like an event or something like that? But if i do that then it'll only be whenever that event is executed and not every X minutes. :/
EDIT: Or do you mean that i should put it in a public void method and call that method when needed?

 

@timtower Like this?:

Code:

public class ClassName {
   
    private Main plugin;
   
    public ClassName(Main plugin) {
        this.plugin = plugin;
        Bukkit.getServer().getScheduler().scheduleSyncRepeatingTask(plugin, new Runnable() {
            @Override
            public void run() {
                // Do something
            }
        }, 0L, 20L);
    }
}

 

@timtower Then how would i call it every X minutes?
EDIT: Just by doing "new ClassName(this);" in the onEnable?

 

@timtower Yeah, i haven't done anything with the runnable yet but this is how i plan to use the Main and Runnable class:
Main

Code:Java

 
public class Main extends JavaPlugin {
 
    public void onEnable() {
        new ClassName(this);
    }
}
 

Runnable class:

Code:Java

 
public class ClassName {
 
    private Main plugin;
 
    public ClassName(Main plugin) {
        this.plugin = plugin;
        Bukkit.getServer().getScheduler().scheduleSyncRepeatingTask(plugin, new Runnable() {
            @Override
            public void run() {
                // Do something
            }
        }, 0L, 20L);
    }
}
 

 

@timtower Would it be possible to make it so that it only runs when a minimum of 1 player is online? (Then it won't run when no-one is online)

 

@timtower Like this?:

Code:Java

 
public class ClassName {
 
    private Main plugin;
 
    public ClassName(Main plugin) {
        this.plugin = plugin;
        if (any players are online) {
            Bukkit.getServer().getScheduler().scheduleSyncRepeatingTask(plugin, new Runnable() {
                @Override
                public void run() {
                    // Do something
                }
            }, 0L, 20L);
        }
    }
}
 

I don't know how to check if any players are online. Could you let me know?

 

@timtower Oh, like this then?:

Code:Java

 
public class ClassName {
 
    private Main plugin;
 
    public ClassName(Main plugin) {
        this.plugin = plugin;
        Bukkit.getServer().getScheduler().scheduleSyncRepeatingTask(plugin, new Runnable() {
            @Override
            public void run() {
                if (any players are online) {
                    // Do something
                }
            }
        }, 0L, 20L);
    }
}
 

Still don't know how to check if any players are online. :/ Did a quick search but didn't find anything.
EDIT: My guess is i need to loop through all players and check if any of them are online or something like that.

 

@timtower Okay, thanks. And would .empty() check if the server is empty of players or what does it do?

 

@timtower I don't know what a collection is or how i use it. :/

 

@timtower Would this work?

Code:Java

 
public class ClassName {
 
    private Main plugin;
 
    public ClassName(Main plugin) {
        this.plugin = plugin;
        Bukkit.getServer().getScheduler().scheduleSyncRepeatingTask(plugin, new Runnable() {
            @Override
            public void run() {
                if (!plugin.getServer().getOnlinePlayers().isEmpty()) {
                    // Do something
                }
            }
        }, 0L, 20L);
    }
}
 

 

@timtower The "20L" at the bottom is the time in ticks, right? Also i tried changing the "new Runnable" to "new BukkitRunnable" then import and it came with alot of errors and deprecated and stuff, how would i change it to BukkitRunnable?

 

@timtower runTaskTimer would still repeat doing this every X time i put at the "20L", right?

 

@timtower No i haven't, but doesn't it show what is available when i hover over the text? Anyway i tried this but it still came with errors:

Code:Java

 
public class ClassName {
 
    private Main plugin;
 
    public ClassName(Main plugin) {
        this.plugin = plugin;
        Bukkit.getServer().getScheduler().runTaskTimer(plugin, new BukkitRunnable(), 0, 20) {
            @Override
            public void run() {
                if (!plugin.getServer().getOnlinePlayers().isEmpty()) {
                    // Do something
                }
            }
        }
    }
}
 

I don't know how i should use this "runTaskTimer" method. :/
EDIT: New code, but still doesn't work:

Code:Java

 
public class ClassName {
 
    private Main plugin;
 
    public ClassName(Main plugin) {
        this.plugin = plugin;
        Bukkit.getScheduler().runTaskTimer(plugin, new BukkitRunnable() {
            @Override
            public void run() {
                if (!plugin.getServer().getOnlinePlayers().isEmpty()) {
                    // Do something
                }
            }
        }, 0, 20);
    }
}
 

EDIT: Looks like i found something that doesn't come with any errors, is this correct?:

Code:Java

 
public class ClassName {
 
    private Main plugin;
 
    public ClassName(Main plugin) {
        this.plugin = plugin;
        new BukkitRunnable() {
            @Override
            public void run() {
                if (!plugin.getServer().getOnlinePlayers().isEmpty()) {
                    // Do something
                }
            }
        }.runTaskTimer(plugin, 0, 20);
    }
}
 

 

@timtower Just tried testing it by doing this:

Code:Java

 
public class ClassName {
 
    @SuppressWarnings("unused")
    private Main plugin;
 
    public ClassName(Main plugin) {
        this.plugin = plugin;
        new BukkitRunnable() {
            @Override
            public void run() {
                if (!plugin.getServer().getOnlinePlayers().isEmpty()) {
                    Bukkit.getConsoleSender().sendMessage("It works!");
                }
            }
        }.runTaskTimer(plugin, 0, 200);
    }
}
 

And the Main class is just like this:

Code:Java

 
public class Main extends JavaPlugin {
 
    public void onEnable() {
        new ClassName(this);
    }
}
 

And it sends the message "It works!" to the console every 10 seconds if i'm on the server, if not it doesn't do anything so i guess it works. On to the next thing, how would i refill all chests within a certain area?