Preventing use of magic but allowing use of colour codes.

ChatColor.translateAltColorCodes( '&', "&kMessage".replace( "&k", "" ) )

 

Look at the arrangment and where .replace is. It would be args[0].replace( ... )

 

It needs to be

Code (Text):

player.sendMessage("New nickname: " + ChatColor.translateAlternateColorCodes('&k', args[0].replace("&k", "")));

Note the replace method is inside the translateAlternateColorCodes().

Edit: Godammit, ninj'd by @_Cory_

 

If you put &&kk in the nickname, your solution will not block the use of &k.

 

Use this:

Code (Text):

while (text.contains("&k")) {
            text = text.replace("&k", "");
        }

 

That is the same as

Code (Java):

text = text.replace("&k", "");

String#replace will already replace all occurrences in the String.

 

Not unless stripping an occurrence creates a new occurrence

 

You could try this:

Code (Text):

ChatColor.translateAlternateColorCodes('&', input).replace(ChatColor.MAGIC, "");

 

One way is to simply not parse &k, with regex like &[a-f0-9] for color codes only

 

Well... I've just provided the one you need.

 

If you put &&kk just a String#replace dont will solve the problem

 

Look into the Pattern and Matcher classes if you want to handle it efficiently. If you don't require efficiency and want simple code, look into String#replaceAll.