java.util.ConcurrentModificationException.

Hello, my plugin throws this exception when the for... starts, can anybody help me please?

This is the peace of code that throws it (there is a "public static List<String> strings = new ArrayList<String>();" in the class "Main") :

Code:java

 for (String cadena : Main.strings) {
int Iusuario = cadena.indexOf("'Usuario: ");
int Iequipo = cadena.indexOf("Equipo: ");
String usuario = cadena.substring(Iusuario + 10, Iequipo - 3);
String equipo = cadena.substring(Iequipo + 8);
if (target.getName().equalsIgnoreCase(usuario)) {
sender.sendMessage(ChatColor.DARK_RED + target.getName() + ChatColor.RED + " ya está en el equipo " + ChatColor.DARK_RED + equipo);
} else {
String nameAndteam = name + " - " + "Equipo: " + team;
Main.strings.add(nameAndteam);
Main.p.getConfig().set("Players", Main.strings);
Main.p.saveConfig();
sender.sendMessage(ChatColor.AQUA + "Se ha añadido a " + ChatColor.DARK_AQUA + target.getName() + ChatColor.AQUA + " al equipo " + ChatColor.DARK_AQUA + team + ChatColor.AQUA + ".");
}
}

This is the error report:

Code:java

Caused by: java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(Unknown Source) ~[?:1.
8.0_25]
at java.util.ArrayList$Itr.next(Unknown Source) ~[?:1.8.0_25]
at command.CustomCommandHandler.command(CustomCommandHandler.java:149) ~
[?:?]
at main.Main.onCommand(Main.java:38) ~[?:?]
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[cra
ftbukkit-betaBuild3092.jar:git-Bukkit-1.7.9-R0.1-10-g8688bd4-b3092jnks]
... 13 more

 

MetalGearDaner
How about you Google search what the error is about?

 

I already done that, but I'm new on coding and I don't really understand how to fix the java.util.concurrentmodificationexception.

 

MetalGearDaner
You're modifying a collection while looping through its contents. In this case, the collection would be your Main.strings list.

Either make an array copy of the list and loop through that, or use an Iterator.