call a method from a different class

so currently I am trying to implement multiple class files to make my code much more readable.
main class, on a command, tries to call Menu.mainMenu() which returns an Inventory.

I dont know how to do this.

here's what I currently have

main:

Code:

@Override
    public boolean onCommand(CommandSender sender, Command cmd, String commandlabel, String[] args) {
        if (!(sender instanceof Player)) {
            sender.sendMessage(prefix + ChatColor.RED + "The console cannot open the item request inventory!");
            return true;
        }
       
        Player player = (Player) sender;
       
        if (player.hasPermission("requests.command")) {
            if (cmd.getName().equalsIgnoreCase("requests")) {
                Inventory requestinv = Menu.mainMenu();
                player.openInventory(requestinv);
            }
        }
        return true;
    }

Menu:

Code:

public class Menu implements Listener {

    public Inventory mainMenu() {
       
        Inventory requestinv = Bukkit.getServer().createInventory(null, 54, ChatColor.GREEN + "The Grand Minechange");
       
        ItemStack invstack = new ItemStack(Material.ARROW, 1);
        ItemMeta invmeta = invstack.getItemMeta();
        invmeta.setUnbreakable(true);
        invmeta.setDisplayName(ChatColor.GREEN + "Next Page");
        invstack.setItemMeta(invmeta);
        requestinv.setItem(51, invstack);
        invstack = new ItemStack(Material.ARROW, 1);
        invmeta = invstack.getItemMeta();
        invmeta.setUnbreakable(true);
        invmeta.setDisplayName(ChatColor.RED + "Previous Page");
        invstack.setItemMeta(invmeta);
        requestinv.setItem(47, invstack);
        invstack = new ItemStack(Material.SUNFLOWER, 1);
        invmeta = invstack.getItemMeta();
        invmeta.setUnbreakable(true);
        invmeta.setDisplayName(ChatColor.YELLOW.toString() + ChatColor.BOLD.toString() + "Create Request");
        invstack.setItemMeta(invmeta);
        invstack.addUnsafeEnchantment(Enchantment.DURABILITY, 10);
        requestinv.setItem(49, invstack);
       
        return requestinv;
       
    }
   
}

 

@timtower
so I included
public Menu menu;
in my main class,
but this error happens when I run the command

Code:

[03:35:09 ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'minechange' in plugin TheGrandMinechange v1.0.0
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[patched_1.13.2.jar:git-Paper-448]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:149) ~[patched_1.13.2.jar:git-Paper-448]
        at org.bukkit.craftbukkit.v1_13_R2.CraftServer.dispatchCommand(CraftServer.java:732) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.PlayerConnection.handleCommand(PlayerConnection.java:1766) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.PlayerConnection.a(PlayerConnection.java:1570) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.PacketPlayInChat.a(PacketPlayInChat.java:45) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.PacketPlayInChat.a(PacketPlayInChat.java:5) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.PlayerConnectionUtils.lambda$ensureMainThread$0(PlayerConnectionUtils.java:12) ~[patched_1.13.2.jar:git-Paper-448]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_191]
        at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_191]
        at net.minecraft.server.v1_13_R2.SystemUtils.a(SystemUtils.java:109) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.MinecraftServer.b(MinecraftServer.java:1016) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.DedicatedServer.b(DedicatedServer.java:439) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.MinecraftServer.a(MinecraftServer.java:943) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.MinecraftServer.run(MinecraftServer.java:841) ~[patched_1.13.2.jar:git-Paper-448]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_191]
Caused by: java.lang.NullPointerException
        at me.Darkolythe.GrandMinechange.GrandMinechange.onCommand(GrandMinechange.java:45) ~[?:?]
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[patched_1.13.2.jar:git-Paper-448]
        ... 15 more

 

@timtower
thats not what I did when I did
public Menu menu;
?

how do I init it?

 

and this needs to be in a method?

also, I'll try to explain this so I better understand it.

public Menu menu gives the main class access to the Menu class.

menu = new Menu() creates a new instance of the Menu class which can be accessed within the method.

is that right?

 

oh okay. thank you!

so now that I have that figured out, how would I go about doing an InventoryClickEvent within the Menu class?
currently its just sitting there and no errors are happening, the code just isnt running.
@timtower

 

I would assume not.
and this doesnt look right

registerEvents(this, new menu.onInventoryClick());

here's that method (which is inside Menu):

Code:

@EventHandler
    public void onInventoryClick(InventoryClickEvent event) {
        System.out.println("x");
        Player player = (Player) event.getWhoClicked();
        if (event.getClickedInventory() != null) {
            if (event.getClickedInventory().getTitle().equals(ChatColor.GREEN + "The Grand Minechange")) {
                if (player.getItemOnCursor().getType() == Material.AIR) {
                    ItemStack clickstack = event.getCurrentItem();
                    if (clickstack.getItemMeta().hasDisplayName()) {
                        if (clickstack.getItemMeta().getDisplayName() == ChatColor.YELLOW.toString() + ChatColor.BOLD.toString() + "Create Request") {
                            System.out.println("ietm");
                        }
                    }
                }
            }
        }
    }

 

in main:

Code:

@Override
    public void onEnable() {
        registerEvents(this, menu);
        System.out.println(prefix + ChatColor.GREEN + "The Grand Minechange Enabled!");
    }

it says "the method registerEvents is undefined for the type GrandMinechange

and thanks!

@timtower

 

so I need to add a method inside the Menu class too?
I'm just as unsure about what I'm doing than I was before...
@timtower

a multitple class tutorial on the forums said to do this, but this doesnt work either

Code:

//Much eaisier then registering events in 10 diffirent methods
    public static void registerEvents(org.bukkit.plugin.Plugin plugin, Listener... listeners) {
        for (Listener listener : listeners) {
            Bukkit.getServer().getPluginManager().registerEvents(listener, plugin);
        }
    }

I tried this now too, but its not working either

getServer().getPluginManager().registerEvents(this, menu);

ok, I've been trying this for 30 minutes now, I really don't know what to do

I tried the things in the API and none of it worked.

 

Even if I do
RegisterEvents(menu, this);

My IDE says its wrong

 

ohhhhh. thanks!

also, since I have a lot of questions about this stuff. do I create a new thread for each one? or..

 

how do I get access to a main class method from a different class file?

I have a method:

Code:

    public long getCooldown(UUID uuid) {
       
        long timeleft = System.currentTimeMillis() - cooldown.get(uuid);
       
        return timeleft;
       
    }

that I want to access from Menu

 

@thechrisanator You can do something like this:

Code:Java

//Inside some class with methods
public long getCooldown(UUID uuid) {
    long timeleft = System.currentTimeMillis() - cooldown.get(uuid);
    return timeleft;
}

Code:Java

//Inside main class
private ClassWithMethodsNameHere whatever;
 
private static MainClassNameHere instance;
 
public void onEnable() {
    instance = this;
    whatever = new ClassWithMethodsNameHere();
}
 
public static MainClassNameHere getInstance() {
    return instance;
}
 
public ClassWithMethodsNameHere getClassWithMethods() {
    return whatever;
}

Code:Java

//Inside Menu class
private MainClassNameHere main = MainClassNameHere.getInstance();
 
//Then to use methods do this
main.getClassWithMethods().getCooldown(uuid);

Hope this helped somehow, if you didn't understand what is going on i could try explaining it, just ask the question.

 

No, that was just one way to do it and it uses less code in the long run.
EDIT: I use constructors myself.

 

what do you mean pass the initialization of Main to the onEnable() ?
and what do you mean using the constructor?

@timtower

 

so I moved
"public Menu menu = new Menu();"
to onEnable(),
but my IDE says "illegal modifier for parameter menu; only final is permitted"

I also tried removing the "public", but now my other methods dont have access to menu

 

alright! I figured it out thanks to the help of you and KarimAKL!
thanks!
chances are, Ill be coming back here soon haha. using multiples files is tricky at first, but hopefully Ill catch on to it quickly

@timtower

update:

my InventoryClickEvent doesnt want to work:

error:

Code:

[16:20:09 ERROR]: Could not pass event InventoryClickEvent to TheGrandMinechange v1.0.0
org.bukkit.event.EventException: null
        at org.bukkit.plugin.EventExecutor$2.execute(EventExecutor.java:72) ~[patched_1.13.2.jar:git-Paper-448]
        at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:78) ~[patched_1.13.2.jar:git-Paper-448]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[patched_1.13.2.jar:git-Paper-448]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:513) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.PlayerConnection.a(PlayerConnection.java:2280) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.PacketPlayInWindowClick.a(SourceFile:33) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.PacketPlayInWindowClick.a(SourceFile:10) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.PlayerConnectionUtils.lambda$ensureMainThread$0(PlayerConnectionUtils.java:12) ~[patched_1.13.2.jar:git-Paper-448]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_191]
        at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_191]
        at net.minecraft.server.v1_13_R2.SystemUtils.a(SystemUtils.java:109) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.MinecraftServer.b(MinecraftServer.java:1016) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.DedicatedServer.b(DedicatedServer.java:439) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.MinecraftServer.a(MinecraftServer.java:943) ~[patched_1.13.2.jar:git-Paper-448]
        at net.minecraft.server.v1_13_R2.MinecraftServer.run(MinecraftServer.java:841) ~[patched_1.13.2.jar:git-Paper-448]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_191]
Caused by: java.lang.NullPointerException
        at me.Darkolythe.GrandMinechange.Menu.onInventoryClick(Menu.java:60) ~[?:?]
        at com.destroystokyo.paper.event.executor.asm.generated.GeneratedEventExecutor144.execute(Unknown Source) ~[?:?]
        at org.bukkit.plugin.EventExecutor$2.execute(EventExecutor.java:70) ~[patched_1.13.2.jar:git-Paper-448]
        ... 15 more

menu:

Code:

public void onInventoryClick(InventoryClickEvent event) {
       
        int cooldowntimer = 30; //(30 minutes)
       
        Player player = (Player) event.getWhoClicked();
        if (event.getClickedInventory() != null) {
            if (event.getClickedInventory().getTitle().equals(ChatColor.GREEN.toString() + ChatColor.BOLD.toString() + "The Grand Minechange")) {
                if (player.getItemOnCursor().getType() == Material.AIR) {
                    ItemStack clickstack = event.getCurrentItem();
                    if (clickstack.getItemMeta().hasDisplayName()) {
                        if (clickstack.getItemMeta().getDisplayName().equals(ChatColor.YELLOW.toString() + ChatColor.BOLD.toString() + "Create Request")) {
                            System.out.println("xxx");
                            long timeleft = System.currentTimeMillis() - main.getCooldown(player.getUniqueId());
                            if (timeleft > cooldowntimer * 60000) {
                                Inventory crinv = createrequest.createInventory();
                                player.openInventory(crinv);
                            } else {
                                player.sendMessage(main.prefix + ChatColor.RED + "You must wait before making another request!\nTime left:" + Integer.toString((int)timeleft / 1000) + 's');
                            }
                        }
                    }
                }
                event.setCancelled(true);
            }
        }
    }

main:

Code:

public long getCooldown(UUID uuid) {
        System.out.println("x");
        if (cooldown.containsKey(uuid)) {
            return System.currentTimeMillis() - cooldown.get(uuid);
        } else {
            cooldown.put(uuid, System.currentTimeMillis() + (30 * 60000));
            return System.currentTimeMillis() - cooldown.get(uuid);
        }
    }

EDIT by Moderator: merged posts, please use the edit button instead of double posting.