[1.12.2] Description: Exception in server tick loop

[NightBlood]

Hey, Im kinda new to forge modding and I was wondering which is the best way to implement a timer within a HarvestDropsEvent and a RightClickItem Events
Ive been using a java.util.TimerTask but it has had ticks sync issues.
I know this might be something simple but I havent been able to figure that out, thanks in advance.

 

Edit: Code added.
I just need the EntityFallingBlock to spawn every X seconds without using a  java.util.TimerTask the way a Bukkit.getScheduler().sheduleSyncRepeatingTask for Spigot does.

 

Error:

Description: Exception in server tick loop

java.util.ConcurrentModificationException
    at java.util.HashMap$HashIterator.nextNode(HashMap.java:1442)
    at java.util.HashMap$KeyIterator.next(HashMap.java:1466)
    at net.minecraft.entity.EntityTracker.tick(EntityTracker.java:295)
    at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:854)
    at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:743)
    at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:192)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:592)
    at java.lang.Thread.run(Thread.java:748)

 

Code:

int i2 = 0;
int max = 5;
timer.schedule(new TimerTask() {
  @Override
    public void run() {
    if (i2 >= max) this.cancel();
    if (i2 >= max) return;
    i2++;
    EntityFallingBlock tnt = new EntityFallingBlock(world, pos.getX()+0.5, pos.getY()+10, pos.getZ()+0.5, Blocks.TNT.getDefaultState());
    tnt.fallTime = 1;
    world.spawnEntity(tnt);
  }
}, 0, 500);

 

Edited July 19, 2019 by NightBlood
Information added

[Draco18s]

Don't modify a collection that you are itterating over.

 

Also.

 

Post your code.

[NightBlood]

Edited.

[Draco18s]

Don't use timer tasks. Use an event handler, subscribe to the world tick event, and count ticks.