Asynchronous Block Remove Error

Code:java

public class walls implements Runnable {
  public Player player1 = null;
  public Location l = null;
  public void setPlayer(Player player) {
    player1 = player;
  }
  public void setLocation(Location lo) {
    l = lo;
  }
  @Override
  public void run() {
    Player player = player1;
    Location loc = l;
    try {
      Thread.sleep(5000);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    for (int x = 0; x <= 2; x++) {
      for (int y = 0; y <= 3; y++) {
        for (int z = 0; z <= 2; z++) {
          if (loc.getBlock().getLocation().add(x - 1, y - 1, z - 1).getBlock().getType().equals(Material.ICE))
            loc.getBlock().getLocation().add(x - 1, y - 1, z - 1).getBlock().setType(Material.AIR);
          }
        }
      }
      player.sendMessage(ChatColor.AQUA + "You are no longer frozen.");
    }
  }
}

Code:

013-09-29 00:25:11 [SEVERE] Exception in thread "Thread-36"
2013-09-29 00:25:11 [SEVERE] java.lang.IllegalStateException: Asynchronous block remove!
2013-09-29 00:25:11 [SEVERE] at net.minecraft.server.v1_6_R3.Block.remove(Block.java:350)
2013-09-29 00:25:11 [SEVERE] at net.minecraft.server.v1_6_R3.Chunk.a(Chunk.java:390)
2013-09-29 00:25:11 [SEVERE] at net.minecraft.server.v1_6_R3.World.setTypeIdAndData(World.java:351)
2013-09-29 00:25:11 [SEVERE] at org.bukkit.craftbukkit.v1_6_R3.block.CraftBlock.setTypeId(CraftBlock.java:108)
2013-09-29 00:25:11 [SEVERE] at org.bukkit.craftbukkit.v1_6_R3.block.CraftBlock.setType(CraftBlock.java:104)
2013-09-29 00:25:11 [SEVERE] at me.SoSDylan.mKitPvP.Kits.Freezer$walls.run(Freezer.java:228)
2013-09-29 00:25:11 [SEVERE] at java.lang.Thread.run(Unknown Source)

 

Do not access BukkitAPI methods from an async task.
Only the main server task may do this.

Have a look at Bukkit scheduler methods. "runTaskLater()" or whatever fits your needs.
But use a sync one here.

 

Thanks CubieX