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IllegalStateException: TimeSkipEvent may only be triggered synchronously

I get this message when trying to change the world time asynchronously
java.lang.IllegalStateException: TimeSkipEvent may only be triggered synchronously.
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:595) ~[patched_1.16.3.jar:git-Paper-253]
at org.bukkit.craftbukkit.v1_16_R2.CraftWorld.setFullTime(CraftWorld.java:948) ~[patched_1.16.3.jar:git-Paper-253]
at org.bukkit.craftbukkit.v1_16_R2.CraftWorld.setTime(CraftWorld.java:936) ~[patched_1.16.3.jar:git-Paper-253]
at ru.lmpx.lmpxserverkit.handlers.NightSkipHandler.lambda$onPlayerSleep$0(NightSkipHandler.java:29) ~[?:?]
at org.bukkit.craftbukkit.v1_16_R2.scheduler.CraftTask.run(CraftTask.java:99) ~[patched_1.16.3.jar:git-Paper-253]
at org.bukkit.craftbukkit.v1_16_R2.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:54) ~[patched_1.16.3.jar:git-Paper-253]
at com.destroystokyo.paper.ServerSchedulerReportingWrapper.run(ServerSchedulerReportingWrapper.java:22) ~[patched_1.16.3.jar:git-Paper-253]
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.8.0_271]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.8.0_271]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_271]
#EventHandler
public void onPlayerSleep(PlayerBedEnterEvent e) {
if (!(plugin.getConfig().getBoolean("skipNight.enable"))) return;
if (e.getBedEnterResult().equals(PlayerBedEnterEvent.BedEnterResult.OK)) {
if (plugin.getConfig().getBoolean("skipNight.instantSkip")) {
Bukkit.getWorld("world").setTime(0);
Bukkit.getWorld("world").setStorm(false);
} else {
Bukkit.getScheduler().runTaskAsynchronously(plugin, () -> {
while (Bukkit.getWorld("world").getTime() < 24000) {
Bukkit.getWorld("world").setTime(Bukkit.getWorld("world").getTime() + 10);
try {
Thread.sleep(10);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
}
});
}
}
}
What needs to be changed so that the asynchronous thread changes time without an IllegalStateException error?

The exception is explicit, you cannot call a synchronous method asynchronously. This is to ensure that thread safety is upheld. To fix your code, you would need to change out runTaskAsynchronously() with runTask(), however, with your current code, this would freeze the main thread.
A better solution is to use the runTaskTimer() method. You can create a new class that extends BukkitRunnable. The below code is untested but it should be close to what you need:
import org.bukkit.Bukkit;
import org.bukkit.World;
import org.bukkit.scheduler.BukkitRunnable;
public class BedTask extends BukkitRunnable {
#Override
public void run() {
World world = Bukkit.getWorld("world");
if(world.getTime() >= 24000){
this.cancel();
return;
}
world.setTime(world.getTime() + 10);
}
}
And you could then execute it like:
int sleepWaitPeriod = 10;
new BedTask().runTaskTimer(plugin, 0L, sleepWaitPeriod * 20);

Exception in thread "JavaFX Application Thread" java.lang.IllegalArgumentException:

Here is the error
Exception in thread "JavaFX Application Thread" java.lang.IllegalArgumentException: Children: duplicate children added: parent = Group#5ea0c6fc
at javafx.graphics/javafx.scene.Parent$3.onProposedChange(Unknown Source)
at javafx.base/com.sun.javafx.collections.VetoableListDecorator.add(Unknown Source)
at project1.Crab.setCrab(Crab.java:45)
at project1.SeaAnimals.addCrab(SeaAnimals.java:65)
at project1.ProjectOne.mouseClick(ProjectOne.java:133)
at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(Unknown Source)
at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source)
at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source)
at javafx.base/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(Unknown Source)
at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(Unknown Source)
at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(Unknown Source)
at javafx.base/javafx.event.Event.fireEvent(Unknown Source)
at javafx.graphics/javafx.scene.Scene$ClickGenerator.postProcess(Unknown Source)
at javafx.graphics/javafx.scene.Scene$ClickGenerator.access$8300(Unknown Source)
at javafx.graphics/javafx.scene.Scene$MouseHandler.process(Unknown Source)
at javafx.graphics/javafx.scene.Scene$MouseHandler.access$1300(Unknown Source)
at javafx.graphics/javafx.scene.Scene.processMouseEvent(Unknown Source)
at javafx.graphics/javafx.scene.Scene$ScenePeerListener.mouseEvent(Unknown Source)
at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(Unknown Source)
at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(Unknown Source)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(Unknown Source)
at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(Unknown Source)
at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(Unknown Source)
at javafx.graphics/com.sun.glass.ui.View.handleMouseEvent(Unknown Source)
at javafx.graphics/com.sun.glass.ui.View.notifyMouse(Unknown Source)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(Unknown Source)
at java.base/java.lang.Thread.run(Unknown Source)
Here is the lines of code that have the problem
public class Crab {
private final Image c = new Image("File:crab.gif");
private ArrayList<ImageView> crabList = new ArrayList<ImageView>();
private int _counter;
private Group _crab = new Group();
/** Constructor <br>
* Initializes counter to -1
*/
public Crab() {
_counter = -1;
}
/** Setter <br>
* Adds a crab to the array list
*/
public void addCrab() {
if(_counter < 5) {
crabList.add(new ImageView(c));
_counter++;
}
}
/** Setter <br>
* Deletes a crab from the array list
*/
public void deleteCrab() {
if(_counter > 0) {
crabList.remove(_counter);
_counter--;
}
}
/** Getter <br>
*
* #return returns crab group
*/
public Group setCrab() {
if(_counter >= 0) { //adds the first crab
crabList.get(0).setTranslateX(80);
crabList.get(0).setTranslateY(500);
crabList.get(0).setFitHeight(100);
crabList.get(0).setFitWidth(100);
_crab.getChildren().add(crabList.get(0));
if(_counter >= 1) { //adds the second crab
crabList.get(1).setTranslateX(230);
crabList.get(1).setTranslateY(500);
crabList.get(1).setFitHeight(100);
crabList.get(1).setFitWidth(100);
_crab.getChildren().add(crabList.get(1));
if (_counter >= 2) { // adds the third crab
crabList.get(2).setTranslateX(380);
crabList.get(2).setTranslateY(500);
crabList.get(2).setFitHeight(100);
crabList.get(2).setFitWidth(100);
_crab.getChildren().add(crabList.get(2));
if (_counter >= 3) { //adds the fourth crab
crabList.get(3).setTranslateX(530);
crabList.get(3).setTranslateY(500);
crabList.get(3).setFitHeight(100);
crabList.get(3).setFitWidth(100);
_crab.getChildren().add(crabList.get(3));
if (_counter >= 4) { //adds the fifth crab
crabList.get(4).setTranslateX(680);
crabList.get(4).setTranslateY(500);
crabList.get(4).setFitHeight(100);
crabList.get(4).setFitWidth(100);
_crab.getChildren().add(crabList.get(4));
if (_counter == 5) { //adds the sixth crab
crabList.get(5).setTranslateX(830);
crabList.get(5).setTranslateY(500);
crabList.get(5).setFitHeight(100);
crabList.get(5).setFitWidth(100);
_crab.getChildren().add(crabList.get(5));
}
}
}
}
}
}
return _crab;
}
}
public Group addCrab() {
_crab.addCrab();
_gCrab = _crab.setCrab();
return _gCrab;
}
public Group deleteCrab() {
_crab.deleteCrab();
_gCrab = _crab.setCrab();
return _gCrab;
}
}
public void mouseClick(MouseEvent mouse) {
if(mouse.getClickCount() == 1) {
root.getChildren().remove(gCrab);
gCrab.getChildren().clear();
gCrab.getChildren().add(animals.addCrab());
root.getChildren().add(gCrab);
}
else if(mouse.getClickCount() == 2) {
root.getChildren().remove(gCrab);
gCrab.getChildren().clear();
gCrab.getChildren().add(animals.deleteCrab());
root.getChildren().add(gCrab);
}
}
I do not know how to fix the problem, nor do I know what the problem is. Any help is appreciated.

Your setCrab method attempts to add all the crab images to the Group without removing any of the children. This way if there were crabs in the Group before you're trying to add them again which results in the exception since JavaFX does not allow this.
You also need to make sure never to add the same node twice to the same parent.
Furthermore hiding the setCrab from the user of the Crab class would reduce the complexity of using the class. Why make the user call 2 methods when 1 call would do the same job. You could even write a CrabGroup class that is a node itself and aviod the removing and readding of the Group to it's parent.
E.g.
public class CrabGroup extends HBox {
private static final Image c = new Image("File:crab.gif");
public CrabGroup() {
setSpacing(50);
}
/**
* Adds a crab
*/
public void addCrab() {
if(getChildren().size() < 6) {
ImageView image = new ImageView(c);
image.setFitWidth(100);
image.setFitHeight(100);
crabList.add(image);
}
}
/**
* Deletes a crab
*/
public void deleteCrab() {
if(!getChildren().isEmpty()) {
getChildren().remove(getChildren().size() - 1);
}
}
}
CrabGroup crabGroup = new CrabGroup();
crabGroup.setTranslateX(80);
crabGroup.setTranslateY(500);
crabGroup.addCrab();
...
crabGroup.deleteCrab();

ZipException: zip END header not found in java-9

util.zip.ZipException: zip END header not found
exception when try to load javafx fxml view in java-9.
Details
My Application is a Javafx(uses fxml view) which is built and compiled using java-8(jdk-8 64-bit) and accessed as a WebStart with jre-9(64-bit).
Webpages(xhtml) are loaded and rendered in this javafx application.
Also note that
There are already two similar bugs reported (ie. JDK-8170276, JDK-8172872) and
these two bugs mentioned that the issue is not reproducible with latest java-9
but reproducible only with earlier java-9 ea build version.
But in my case, im using latest java-9(9.0.4 version) and
its always reproducible.
Problem
When i try to load fxml popup after login, get below exceptions.
java.util.zip.ZipException: zip END header not found
at java.base/java.util.zip.ZipFile$Source.zerror(Unknown Source)
at java.base/java.util.zip.ZipFile$Source.findEND(Unknown Source)
at java.base/java.util.zip.ZipFile$Source.initCEN(Unknown Source)
at java.base/java.util.zip.ZipFile$Source.<init>(Unknown Source)
at java.base/java.util.zip.ZipFile$Source.get(Unknown Source)
at java.base/java.util.zip.ZipFile.<init>(Unknown Source)
at java.base/java.util.zip.ZipFile.<init>(Unknown Source)
at java.base/java.util.jar.JarFile.<init>(Unknown Source)
at java.base/sun.net.www.protocol.jar.URLJarFile.<init>(Unknown Source)
at java.base/sun.net.www.protocol.jar.URLJarFile.<init>(Unknown Source)
at java.base/sun.net.www.protocol.jar.URLJarFile$1.run(Unknown Source)
at java.base/sun.net.www.protocol.jar.URLJarFile$1.run(Unknown Source)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/sun.net.www.protocol.jar.URLJarFile.retrieve(Unknown Source)
at java.base/sun.net.www.protocol.jar.URLJarFile.getJarFile(Unknown Source)
at java.base/sun.net.www.protocol.jar.JarFileFactory.get(Unknown Source)
at java.base/sun.net.www.protocol.jar.JarURLConnection.connect(Unknown Source)
at jdk.deploy#9.0.1/com.sun.deploy.net.protocol.jar.DeployURLConnection.connect(Unknown Source)
at jdk.deploy#9.0.1/com.sun.deploy.net.protocol.jar.DeployURLConnection.getInputStream(Unknown Source)
at java.base/java.net.URL.openStream(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader.load(Unknown Source)
at client.FxmlWrapper.initialize(FxmlWrapper.java:57)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$9(Unknown Source)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(Unknown Source)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(Unknown Source)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(Unknown Source)
at java.base/java.lang.Thread.run(Unknown Source)
Suppressed: java.nio.file.NoSuchFileException: C:\Users\user\AppData\Local\Temp\jar_cache8046747560626483610.tmp
at java.base/sun.nio.fs.WindowsException.translateToIOException(Unknown Source)
at java.base/sun.nio.fs.WindowsException.rethrowAsIOException(Unknown Source)
at java.base/sun.nio.fs.WindowsException.rethrowAsIOException(Unknown Source)
at java.base/sun.nio.fs.WindowsFileSystemProvider.implDelete(Unknown Source)
at java.base/sun.nio.fs.AbstractFileSystemProvider.delete(Unknown Source)
at java.base/java.nio.file.Files.delete(Unknown Source)
... 22 common frames omitted
Request if anyone could help on this issue,would be grateful.
Many Thanks.
Although this is not the full code, but this is the code for showing fxml popup which throws "java.util.zip.ZipException: zip END header not found" exceptions in java-9, but in java-8 works fine.
PopupAction.java
public class PopupAction
{
public PopupAction()
{
super();
}
public void showPopup()
{
CountDownLatch latch = new CountDownLatch(1);
Platform.runLater(
new PopupHandler(latch, "testMsg", "testTitle", "testButtonText"));
try
{
latch.await();
}
catch(InterruptedException localInterruptedException)
{
Thread.currentThread().interrupt();
}
}
}
PopupHandler.java
public class PopupHandler implements Runnable
{
private CountDownLatch latch;
private String message;
private String title;
private String buttonText;
public PopupHandler(CountDownLatch latch,
String message, String title, String buttonText)
{
this.latch = latch;
this.message = message;
this.title = title;
this.buttonText = buttonText;
}
#Override
public void run()
{
try
{
Stage stage = new Stage(StageStyle.UTILITY);
Parent root;
stage.initModality(Modality.APPLICATION_MODAL);
stage.setResizable(false);
FXMLViewLoader fXMLViewLoader = new FXMLViewLoader("/fxmlView/warningPopup.fxml");
root = fXMLViewLoader.getView();
Scene scene = new Scene(root, 400, 110);
scene.setFill(Color.TRANSPARENT);
stage.setScene(scene);
stage.setResizable(false);
stage.setTitle(this.title);
stage.initOwner(Application.getOwnerWindow());
this.localAtomicBoolean.set(true);
stage.setAlwaysOnTop(true);
stage.showAndWait();
}
catch(Exception e)
{
e.printStackTrace();
}
finally
{
this.latch.countDown();
}
}
}
FXMLViewLoader.java
public final class FXMLViewLoader
{
private FXMLLoader loader;
public FXMLViewLoader(String fxmlName)
{
super();
initialize(fxmlName);
}
private void initialize(String fxmlName)
{
final URL resource = getResourceURL(fxmlName);
this.loader = new FXMLLoader(resource);
try
{
this.loader.load();
}
catch(Exception e)
{
e.printStackTrace();
}
}
protected URL getResourceURL(String fxmlName)
{
return this.getClass().getResource(fxmlName);
}
public Parent getView()
{
return this.loader.getRoot();
}
}

instance is null after renaming project

I'm working in IntelliJ and I attempted to rename my Project! After doing so, and renaming everything, which I believe I did correctly, I'm unable to actually start my application.
Error:
org.bukkit.plugin.InvalidPluginException: java.lang.NullPointerException
at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:133) ~[spigot-latest.jar:git-Spigot-4df3c0c-03f1e37]
at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:326) ~[spigot-latest.jar:git-Spigot-4df3c0c-03f1e37]
at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:248) [spigot-latest.jar:git-Spigot-4df3c0c-03f1e37]
at org.bukkit.craftbukkit.v1_12_R1.CraftServer.loadPlugins(CraftServer.java:302) [spigot-latest.jar:git-Spigot-4df3c0c-03f1e37]
at net.minecraft.server.v1_12_R1.DedicatedServer.init(DedicatedServer.java:205) [spigot-latest.jar:git-Spigot-4df3c0c-03f1e37]
at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:544) [spigot-latest.jar:git-Spigot-4df3c0c-03f1e37]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_121]
Caused by: java.lang.NullPointerException
at me.craftblock.MochaMessages.Config.<init>(Config.java:7) ~[?:?]
at me.craftblock.MochaMessages.MochaMessages.<init>(MochaMessages.java:18) ~[?:?]
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.8.0_121]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) ~[?:1.8.0_121]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) ~[?:1.8.0_121]
at java.lang.reflect.Constructor.newInstance(Unknown Source) ~[?:1.8.0_121]
at java.lang.Class.newInstance(Unknown Source) ~[?:1.8.0_121]
at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:76) ~[spigot-latest.jar:git-Spigot-4df3c0c-03f1e37]
at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:129) ~[spigot-latest.jar:git-Spigot-4df3c0c-03f1e37]
... 6 more
The error points to my Config class, however I'm not sure why:
public class Config {
private MochaMessages instance = MochaMessages.getInstance();
private FileConfiguration config = instance.getConfig();
public Config() {
}
public String get(String node) {
System.out.println("Fetching: " + node);
return config.getString(node);
}
public void set(String node, String value) {
config.set(node, value);
}
public boolean getBoolean(String node) {
System.out.println("Fetching: " + node);
return config.getBoolean(node);
}
}
Which is being called via my MochaMessages class:
Here's the related method:
private static MochaMessages instance;
private Config config = new Config();
public void onEnable() {
instance = this;
createConfig();
te = getTokenEnchant();
if (!config.getBoolean("database.enabled")) {
disablePlugin("Enable MySQL!");
} else if (config.get("mocha.currency").equalsIgnoreCase("TokenEnchant")) {
if (te == null) {
disablePlugin("Unable to access TokenEnchant. Disabling Plugin!");
}
} else {
Bukkit.getServer().getPluginManager().registerEvents(new MochaListener(), this);
new MochaModel().createTable();
new CommandHandler();
}
}
I believe it's because instance is returning null even though it shouldn't be. This worked perfectly before the rename!
What's going on?

Minecraft One Player Per Config

I'm going to try to make this quick basically i'm trying to make ONE config per player.
So basically when ever I call user.CreateUser(); if the user doesn't exist it registers there own config with there unique id as the name of the yml
My problem is that when ever I try to call user.CreateUser(); on the PlayerJoinEvent it shows a error and i'm not sure the UUID u shouldn't be returning null because it's inside a constructor or the other variables.
Error
[23:57:52 ERROR]: Could not pass event PlayerJoinEvent to MCEnhanced v1.0
org.bukkit.event.EventException
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:310) ~[spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:62) ~[spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.j
ava:502) [spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:487) [spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at net.minecraft.server.v1_8_R3.PlayerList.onPlayerJoin(PlayerList.java:
296) [spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at net.minecraft.server.v1_8_R3.PlayerList.a(PlayerList.java:156) [spigo
t-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at net.minecraft.server.v1_8_R3.LoginListener.b(LoginListener.java:144)
[spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at net.minecraft.server.v1_8_R3.LoginListener.c(LoginListener.java:54) [
spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at net.minecraft.server.v1_8_R3.NetworkManager.a(NetworkManager.java:231
) [spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at net.minecraft.server.v1_8_R3.ServerConnection.c(ServerConnection.java
:148) [spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:8
17) [spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:3
67) [spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:6
57) [spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java
:560) [spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_45]
Caused by: java.lang.NullPointerException
at crypted.mcenhanced.Handlers.UserDataHandler.CreateUser(UserDataHandle
r.java:46) ~[?:?]
at crypted.mcenhanced.Mechanics.ConfigMechanics.CreateUser.CreateUser(Cr
eateUser.java:19) ~[?:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0
_45]
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0
_45]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1
.8.0_45]
at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_45]
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:306) ~[spigot-1.8.7-R0.1-SNAPSHOT-latest.jar:git-Spigot-f928e7a-e91aed8]
... 14 more
CreateUser Listener Class
public class CreateUser implements Listener {
#EventHandler
public void CreateUser(PlayerJoinEvent event){
Player player = event.getPlayer();
UserDataHandler user = new UserDataHandler(player.getUniqueId());
user.CreateUser();
}
}
UserDataHandler Class
import org.bukkit.configuration.file.FileConfiguration;
import org.bukkit.configuration.file.YamlConfiguration;
import org.bukkit.event.Listener;
import java.io.File;
import java.util.UUID;
public class UserDataHandler implements Listener {
UUID u;
File UserFile;
FileConfiguration UserConfig;
//UserDataHandler user = new UserDataHandler(player.getUniqueId()); // Make sure that you have the player.getUniqueId()
public UserDataHandler(UUID u){
this.u = u;
File UserFile = new File("plugins/MCEnhanced/data/" + u + ".yml");
YamlConfiguration UserConfig = YamlConfiguration.loadConfiguration(UserFile);
}
public void CreateUser(){
if ( !(UserFile.exists()) ) {
try {
//Bukkit.getConsoleSender().sendMessage(ChatColor.YELLOW + "[MCEnhanced] Created a new File for " + player.getName() + "(" + player.getUniqueId() + ")");
YamlConfiguration UserConfig = YamlConfiguration.loadConfiguration(UserFile);
UserConfig.save(UserFile);
} catch (Exception e) {
e.printStackTrace();
// Bukkit.getConsoleSender().sendMessage(ChatColor.RED + "[MCEnhanced] Could not create a new File for " + player.getName() + "(" + player.getUniqueId() + ")");
//u.kickPlayer(ChatColor.RED + "We could not create a file for your account!"); // THE PLAYERS CONFIG NEEDS TO BE CREATED!!!!!!!!
}
}
}
public FileConfiguration getUserFile(){
return UserConfig;
}
public void setDefaultUserFile(){
getUserFile().set("MCEnhanced.Info.IsInfected", false);
}
public void saveUserFile(){
try {
getUserFile().save(UserFile);
} catch(Exception e) {
e.printStackTrace();
}
}
}

In the CreateUser method, you are referencing the UserFile field or instance variable of the current UserDataHandler object which is by default null. Your constructor for the UserDataHandler class does not instantiate this UserFile field and instead creates a local File variable inside that constructor which is then never used. The line...
File UserFile = new File("plugins/MCEnhanced/data/" + u + ".yml");
should be...
UserFile = new File("plugins/MCEnhanced/data/" + u + ".yml");
so that the File field is instantiated for that instance.
I would recommend using the lowerCamelCase naming convention to name your variables, fields and methods as well.