Problème d'assignation d'objet dans un tableau

package fr.killuaah.cmd.cmdmanager;


public class Command {

	int argsNumber;
	String prefix;
	
	
	
	
	
	public Command(int argsNumbers, String prefixx) {
		
		commandManager.commandsInstances++;
		commandManager.commandrep[commandManager.commandsInstances-1] = this;
		
		
		
		//Variables de l'objet 
		argsNumber = argsNumbers;
		prefix = prefixx;
		

package fr.killuaah.cmd.cmdmanager;

import java.util.Scanner;



public class commandManager {

	public static int commandsInstances = 0;
	public static Command[] commandrep = {};
	public static void main(String[] args) {
		// TODO Auto-generated method stub

		boolean b = true;
		String[] command;
		Command c = new Command(4,"salut");
		
		while (b) {
			System.out.print(">>");
			Scanner sc = new Scanner(System.in);
			command = sc.nextLine().split(" ");
			System.out.println(commandManager.commandsInstances);
		}
	
		
		
		
	}

	
	
	
}

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
	at fr.killuaah.cmd.cmdmanager.Command.<init>(Command.java:16)
	at fr.killuaah.cmd.cmdmanager.commandManager.main(commandManager.java:16)