How to replace a plus character using Java's String.replaceAll method

Question

What\'s the correct regex for a plus character (+) as the first argument (i.e. the string to replace) to Java\'s replaceAll method in the String class? I can\'t

Answer 1

String str="Hello+Hello";   
str=str.replaceAll("\\+","-");
System.out.println(str);

OR

String str="Hello+Hello";   
str=str.replace(Pattern.quote(str),"_");
System.out.println(str);