in java using regular expressions replace + and - with " + " and " - "

in java im trying to use string.replaceall to replace "+" and "-" with " + " and " - "

However str.replaceall("+"," + ") results in an error,

so I tried str.replaceall("\+"," + ") and str.replaceall("\Q+\E"," + ")

neither worked

after that i tried str.replaceall("\+"," + ") but forgot to mention it originally, but it does not affect my strings which contain "1x^5+2x^4+6x^3+3x^2+4x^0"

Final answer =

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

开发者_开发技巧 str = str.replaceAll("\\-", " - ");

No need for a regex, just use str = str.replace("+", " + ").replace("-", " - ");

Note that since strings are immutable, you need to use the returned string, hence the str = ...

Just use

str.replaceall("\\+"," + ")

Final answer =
str = str.replaceAll("\\+"," + ");
str = str.replaceAll("\\-", " - ");