Dangling meta character '?' near index 0

Problem

String str = "testing??"; 

str = str.replaceAll("?", ""); 
// Please note that the problem is only with replaceAll and not with replace.
str = str.replace("?", "");

When you use the above pattern you get an exception as "Dangling meta character '?' near index 0"


Solution

String str = "testing??"; 

str = str.replaceAll("\\?", ""); 

You can use the above solution when you are replacing * and + symbols

String str = "testing??*+"; 

str = str.replaceAll("\\*", ""); //"Dangling meta character '*' near index 0" 
str = str.replaceAll("\\+", ""); //"Dangling meta character '+' near index 0"