Regex to find integer or decimal from a string in java in a single group?

Question

I am trying (\\d+|\\d+\\.\\d+) on this sample string:

Oats     124   0.99        V    1.65

but it is giving me decimal number

Answer 1

Question not entirely clear, but the first problem I see is . is a magic character in regex meaning any character. You need to escape it with as . There are lots of regex cheat sheets out there, for example JavaScript Regex Cheatsheet

(\d+|\d+\.\d+)

Answer 2

Try this pattern:

\d+(?:\.\d+)?

Edit:
\d+ match 1 or more digit
(?: non capturing group (optional)
   \. '.' character
   \d+ 1 or more digit
)?  Close non capturing group 

Answer 3

You don't need to have a separate patterns for integer and floating point numbers. Just make the decimal part as optional and you could get both type of numbers from a single group.

(\d+(?:\.\d+)?)

Use the above pattern and get the numbers from group index 1.

DEMO

Code:

String s = "Oats     124   0.99        V    1.65";
Pattern regex = Pattern.compile("(\\d+(?:\\.\\d+)?)");
 Matcher matcher = regex.matcher(s);
 while(matcher.find()){
        System.out.println(matcher.group(1));
}

Output:

124
0.99
1.65

Pattern explanation:

• () capturing group .
• \d+ matches one or more digits.
• (?:) Non-capturing group.
• (?:\.\d+)? Matches a dot and the following one or more digits. ? after the non-capturing group makes the whole non-capturing group as optional.

OR

Your regex will also work only if you change the order of the patterns.

(\d+\.\d+|\d+)

DEMO