I have this string "u2x4m5x7" and I want replace all the characters but a number followed by an x with "". The output should be: "2x5x" Just the number followed by the x. But I am getting this: "2x45x7"
I'm doing this:
String string = "u2x4m5x7";
String s = string.replaceAll("[^0-9+x]","");
Please help!!!
Here is a one-liner using String#replaceAll with two replacements:
System.out.println(string.replaceAll("\\d+(?!x)", "").replaceAll("[^x\\d]", ""));
Here is another working solution. We can iterate the input string using a formal pattern matcher with the pattern \d+x. This is the whitelist approach, of trying to match the variable combinations we want to keep.
String input = "u2x4m5x7";
Pattern pattern = Pattern.compile("\\d+x");
Matcher m = pattern.matcher(input);
StringBuilder b = new StringBuilder();
while(m.find()) {
b.append(m.group(0));
}
System.out.println(b)
This prints:
2x5x
String#replaceAll. But keep in mind that replaceAll uses a pattern matcher under the hood, so the second part of my answer is not as ugly as it might appear.
It looks like this would be much simpler by searching to get the match rather than replacing all non matches, but here is a possible solution, though it may be missing a few cases:
\d(?!x)|[^0-9x]|(?<!\d)x
https://regex101.com/r/v6udph/1
Basically it will:
\d(?!x) -- remove any digit not followed by an x[^0-9x] -- remove all non-x/digit characters(?<!\d)x -- remove all x's not preceded by a digitBut then again, grabbing from \dx would be much simpler
Capture what you need to $1 OR any character and replace with captured $1 (empty if |. matched).
String s = string.replaceAll("(\\d+x)|.", "$1");
