Using Bukkit and Java to create a 'repeating task' code on a Minecraft spigot plugin

I am in the process of creating a spigot plugin (using Java and Bukkit language) that will allow me to store the coordinates of players in minecraft (Java edition) in real time.

I want to use a 'scheduler' to do this with a 'repeating task' structure.

I have the following code:

Code:

Bukkit.getServer().getScheduler().scheduleSyncRepeatingTask((Plugin)this, (Runnable)new Runnable() {
@Override
public void run() {
if (main.this.stopRepeater) {
main.this.logToFile(thePlayer, thePlayer.getLocation());
              }
          }
     }, 0L, 20L);
}

However, I am not 100% sure what role the '@Override' and 'new Runnable()' parts of the code are actually playing here. This is the first time I'm using Java/Bukkit/Spigot for a project.

I am aware that 'new Runnable()' is used to create a new runnable thread of code, and that '@Override' method is used to override the parent class - but what is the 'parent class' in this case above?

I haven't been able to find a clear explanation for this as different sites say different things.

I would be so grateful if somebody could clarify this for me!

 

Thanks so much - how does it know that the 'plugin' in runTaskTimer is referring to 'this ' plugin? Should it not be .runTaskTimer((Plugin)this,0,20)?

 

Ok perfect thanks, so the:

Code:

Bukkit.getServer().getScheduler().scheduleSyncRepeatingTask((Plugin)this, (Runnable)new Runnable() {

part is no longer needed and can be entirely replaced by the following?

Code:

new BukkitRunnable(){
   @Override
   public void run() {
    if (main.this.stopRepeater) {
      main.this.logToFile(thePlayer, thePlayer.getLocation());
            }
        }
   }.runTaskTimer(Plugin, 0, 20)

 

so would you replace 'plugin' for 'this'? or how would I refer to the plugin I defined earlier:

Code:

public void onEnable() {
        Bukkit.getServer().getPluginManager().registerEvents((Listener)this, (Plugin)this);

 

@timtower thanks so much - so if I replace '(Listener)this' for 'listener', and '(Plugin)this' for 'plugin', that should work?

Here is the fuller code:

Code:

public class main extends JavaPlugin implements Listener
{
    Logger trackerLogger;
    boolean stopRepeater;
  
    public main() {
        this.trackerLogger = Bukkit.getLogger();
        this.stopRepeater = true;
    }

  public void onEnable() {
        Bukkit.getServer().getPluginManager().registerEvents(Listener, Plugin);
        this.trackerLogger.info("HELLO! WELCOME TO THE TRACKER PLUGIN");
        if(!this.getDataFolder().exists())
        {
            this.getDataFolder().mkdir();
        }
    }
  
    public void onDisable() {
        this.trackerLogger.info("SHUTTING DOWN!");
    }

new BukkitRunnable(){
@Override
public void run() {
if (main.this.stopRepeater) {
main.this.logToFile(thePlayer, thePlayer.getLocation());
       }
     }
  }.runTaskTimer(Plugin, 0, 20)

 

@timtower - I would like to log my own plugins so I can store the output for later analysis.

When you say I don't need my own logger, why is this?

I have now placed a runnable inside the class.

When you say 'you can't have a constructor like that in your code', which constructor do you mean?

Code:

public class main extends JavaPlugin implements Listener
{
    Logger trackerLogger;
    boolean stopRepeater;

    public main() {
        this.trackerLogger = Bukkit.getLogger();
        this.stopRepeater = true;
    }

  public void onEnable() {
        Bukkit.getServer().getPluginManager().registerEvents(this, this);
        this.trackerLogger.info("HELLO! WELCOME TO THE TRACKER PLUGIN");
        if(!this.getDataFolder().exists())
        {
            this.getDataFolder().mkdir();
        }
    }

    public void onDisable() {
        this.trackerLogger.info("SHUTTING DOWN!");
    }

    @EventHandler
    public void onLogin(final PlayerJoinEvent event) {
           new BukkitRunnable(){
              @Override
               public void run() {
                        if (main.this.stopRepeater) {
                                    main.this.logToFile(thePlayer, thePlayer.getLocation());
                                 }
                        }
              }.runTaskTimer(this, 0, 20)

 

@timtower thank you for confirming - so the code above should still work? (now that I have made amendments)

 

Thank you for all your support @timtower!

I have the following code. I am trying to store the coordinates of players on a Minecraft (Java edition) server every second (20 ticks).

The server is a 'paper' server (hosted externally by Shockbyte), and the code was created using a Bukkit API with the Maven tool and the Java programming language.

The coordinates will be stored in the file 'saveTo' (i.e., where the data recorded by the plugin is stored).

Although my code runs fine (with no errors) on eclipse - the software I am using to amend the code - when I try export it as a jar file and then upload it onto my server (in the plugins folder), it doesn't seem to work and I'm not sure why.

I would be so grateful for a helping hand!

Code:

package newestfile.here.newestplugin;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.FileWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.io.File;
import org.bukkit.event.player.PlayerQuitEvent;
import org.bukkit.event.EventHandler;
import org.bukkit.entity.Player;
import org.bukkit.Location;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.Bukkit;
import java.util.logging.Logger;
import org.bukkit.event.Listener;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.scheduler.BukkitRunnable;

public class Main extends JavaPlugin implements Listener
{
    Logger trackerLogger;
    boolean stopRepeater;
   
    public Main() {
        this.trackerLogger = Bukkit.getLogger();
        this.stopRepeater = true;
    }
   
    public void onEnable() {
        Bukkit.getServer().getPluginManager().registerEvents(this,this);
        this.trackerLogger.info("HELLO! WELCOME TO THE TRACKER PLUGIN");
        if(!this.getDataFolder().exists())
        {
            this.getDataFolder().mkdir();
        }
    }
   
    public void onDisable() {
        this.trackerLogger.info("SHUTTING DOWN!");
    }
   
    @EventHandler
    public void onLogin(final PlayerJoinEvent event) {
        final Player thePlayer = event.getPlayer();
        this.stopRepeater = true;
        final Location playerSpawnLocation = new Location(thePlayer.getWorld(), (double)thePlayer.getLocation().getBlockX(), (double)thePlayer.getLocation().getBlockY(), (double)thePlayer.getLocation().getBlockZ());
        this.trackerLogger.info(String.valueOf(thePlayer.getPlayer().getName()) + " is logging in!");
        this.trackerLogger.info("Welcome " + thePlayer.getPlayer().getName() + ". Your current position is: " + playerSpawnLocation);
       
        new BukkitRunnable(){
               public void run() {
                if (Main.this.stopRepeater) {
                  Main.this.logToFile(thePlayer, thePlayer.getLocation());
                        }
                    }
               }.runTaskTimer(this, 0, 20);}
   
    @EventHandler
    public void onQuit(final PlayerQuitEvent event) {
        this.stopRepeater = false;
        this.trackerLogger.info(String.valueOf(event.getPlayer().getName()) + " has left the game");
    }
   
    public void logToFile(final Player currentPlayer, final Location playerCurrentLocation) {
        try {
            final File dataFolder = new File(this.getDataFolder() + File.separator + currentPlayer.getPlayer().getName());
            if (!dataFolder.exists()) {
                dataFolder.mkdir();
            }
            final File saveTo = new File(dataFolder, String.valueOf(currentPlayer.getPlayer().getName()) + ".log");
            if (!saveTo.exists()) {
                saveTo.createNewFile();
            }
            final Date nowDate = new Date();
            final SimpleDateFormat format = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
            final FileWriter fw = new FileWriter(saveTo, true);
            final PrintWriter pw = new PrintWriter(fw);
            pw.println(String.valueOf(format.format(nowDate)) + " CurrentLocation(x,y,z): " + playerCurrentLocation.getBlockX() + " " + playerCurrentLocation.getBlockY() + " " + playerCurrentLocation.getBlockZ());
            pw.close();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }
}

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

 

@timtower - do you mean that I can change lines of code containing 'trackerLogger':

Code:

this.trackerLogger.info(String.valueOf(event.getPlayer().getName()) + " has left the game");
    }

To this:

Code:

Bukkit.getServer().getLogger().info(String.valueOf(event.getPlayer().getName()) + " has left the game");
    }

And when you say constructor, are you saying that this constructor can be removed:

Code:

public Main() {
this.trackerLogger = Bukkit.getLogger();
this.stopRepeater = true;
}

 

Thanks! But then what about 'this.stopRepeater' - if I remove the constructor, I would have to replace this with something else?

 

You mean like this? (I've taken out the logger part as we discussed above)

Code:

public class Main extends JavaPlugin implements Listener
{
    boolean stopRepeater;
   
    public Main() {

 

Sure - so then how should I change this line:

Code:

this.stopRepeater = true;

My code currently looks like this (with errors next to the 'this.stopRepeater' lines:

Code:

package newestfile.here.newestplugin;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.FileWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.io.File;
import org.bukkit.event.player.PlayerQuitEvent;
import org.bukkit.event.EventHandler;
import org.bukkit.entity.Player;
import org.bukkit.Location;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.Bukkit;
import java.util.logging.Logger;
import org.bukkit.event.Listener;
import org.bukkit.plugin.java.JavaPlugin;

public class Main extends JavaPlugin implements Listener
{

    public void onEnable() {
        Bukkit.getServer().getPluginManager().registerEvents(this,this);
        getLogger().info("HELLO! WELCOME TO THE TRACKER PLUGIN");
        if(!this.getDataFolder().exists())
        {
            this.getDataFolder().mkdir();
        }
    }
  
    public void onDisable() {
        getLogger().info("SHUTTING DOWN!");
    }
  
    @EventHandler
    public void onLogin(final PlayerJoinEvent event) {
        final Player thePlayer = event.getPlayer();
        this.stopRepeater = true;
        final Location playerSpawnLocation = thePlayer.getLocation();
        getLogger().info(String.valueOf(thePlayer.getName()) + " is logging in!");
        getLogger().info("Welcome " + thePlayer.getName() + ". Your current position is: " + playerSpawnLocation);
        Bukkit.getServer().getScheduler().scheduleSyncRepeatingTask(this, () -> {
            if(this.stopRepeater) {
                this.logToFile(thePlayer, thePlayer.getLocation());
            }
        }, 0L, 20L);}
  
    @EventHandler
    public void onQuit(final PlayerQuitEvent event) {
        Player thePlayer = event.getPlayer();
        if(!thePlayer.isOnline()) {
            this.stopRepeater = false;
            int taskID = Bukkit.getServer().getScheduler().scheduleSyncRepeatingTask(this, () -> {
                if(this.stopRepeater) {
                    this.logToFile(thePlayer, thePlayer.getLocation());
                }
            }, 0L, 20L);
            Bukkit.getScheduler().cancelTask(taskID);
            getLogger().info(String.valueOf(event.getPlayer().getName()) + " has left the game");
        }
    }
  
    public void logToFile(final Player currentPlayer, final Location playerCurrentLocation) {
        try {
            final File dataFolder = new File(this.getDataFolder() + File.separator + currentPlayer.getName());
            if (!dataFolder.exists()) {
                dataFolder.mkdir();
            }
            final File saveTo = new File(dataFolder, String.valueOf(currentPlayer.getName()) + ".log");
            if (!saveTo.exists()) {
                saveTo.createNewFile();
            }
            final Date nowDate = new Date();
            final SimpleDateFormat format = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
            final FileWriter fw = new FileWriter(saveTo, true);
            final PrintWriter pw = new PrintWriter(fw);
            pw.println(String.valueOf(format.format(nowDate)) + " CurrentLocation(x,y,z): " + playerCurrentLocation.getBlockX() + " " + playerCurrentLocation.getBlockY() + " " + playerCurrentLocation.getBlockZ());
            pw.close();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }
}

 

Yes sorry - I accidentally removed that have added it back in. My current code now looks like this (no errors):

Code:

package newestfile.here.newestplugin;

import java.io.IOException;
import java.util.UUID;
import java.io.PrintWriter;
import java.io.FileWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.io.File;
import org.bukkit.event.player.PlayerQuitEvent;
import org.bukkit.event.EventHandler;
import org.bukkit.entity.Player;
import org.bukkit.Location;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.Bukkit;
import org.bukkit.event.Listener;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.scheduler.BukkitTask;

public class Main extends JavaPlugin implements Listener
{
    boolean stopRepeater;
    HashMap<UUID, BukkitTask> tasks = new HashMap<>();
    public void onEnable() {
        Bukkit.getServer().getPluginManager().registerEvents(this,this);
        getLogger().info("HELLO! WELCOME TO THE TRACKER PLUGIN");
        if(!this.getDataFolder().exists())
        {
            this.getDataFolder().mkdir();
        }
    }
  
    public void onDisable() {
        getLogger().info("SHUTTING DOWN!");
    }
  
    @EventHandler
    public void onLogin(final PlayerJoinEvent event) {
        final Player thePlayer = event.getPlayer();
        this.stopRepeater = true;
        final Location playerSpawnLocation = thePlayer.getLocation();
        getLogger().info(String.valueOf(thePlayer.getName()) + " is logging in!");
        getLogger().info("Welcome " + thePlayer.getName() + ". Your current position is: " + playerSpawnLocation);   
        BukkitTask task = getServer().getScheduler().runTaskTimer(this, () -> {
            if(this.stopRepeater) {
                this.logToFile(thePlayer, thePlayer.getLocation());
            }
        }, 0L, 20L);
        tasks.put(thePlayer.getUniqueId(),task);}
  
    @EventHandler
    public void onQuit(final PlayerQuitEvent event) {
        Player thePlayer = event.getPlayer();
        if(!thePlayer.isOnline()) {
            this.stopRepeater = false;
            getLogger().info(String.valueOf(event.getPlayer().getName()) + " has left the game");
            BukkitTask task = tasks.remove(thePlayer.getUniqueId());
            if(task != null) {
               task.cancel();
            }
        }
    }
  
    public void logToFile(final Player currentPlayer, final Location playerCurrentLocation) {
        try {
            final File dataFolder = new File(this.getDataFolder() + File.separator + currentPlayer.getName());
            if (!dataFolder.exists()) {
                dataFolder.mkdir();
            }
            final File saveTo = new File(dataFolder, String.valueOf(currentPlayer.getName()) + ".log");
            if (!saveTo.exists()) {
                saveTo.createNewFile();
            }
            final Date nowDate = new Date();
            final SimpleDateFormat format = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
            final FileWriter fw = new FileWriter(saveTo, true);
            final PrintWriter pw = new PrintWriter(fw);
            pw.println(String.valueOf(format.format(nowDate)) + " CurrentLocation(x,y,z): " + playerCurrentLocation.getBlockX() + " " + playerCurrentLocation.getBlockY() + " " + playerCurrentLocation.getBlockZ());
            pw.close();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }
}

 

@timtower does that code look ok to you?

 

Although the code seems to run without any errors, I cannot see a '.log' file in the plugins directory on my server. I would be so grateful for a helping hand! @timtower

If I remove this, I will not be able to then print a display message on the screen?

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

 

When I check the latest.log, the coordinates do not seem to be in there.

Shall I put the 'public void logToFile' part of the code above the 'publicvoid onQuit' part of the code?