正则表达式，用于匹配由“ $”字符分隔的正非零双精度字符串

Question

Context : I have found a solution for matching three Integers seperated by the "$" character as seen below:

String toMatch = "123$53$12"; //Returns true
String toMatch2 = "123$0$12"; //Returns false
String toMatch3 = "0$53$12";  //Returns false
String toMatch4 = "123$53$0"; //Returns false
System.out.println(toMatch.matches("\\d+.*\\d+.*\\d+") && !toMatch.matches([^0-9]*0[^0-9]*"));

Problem : What I want to achieve is:

String toMatch = "123.43$.03$123.0"; //Returns true
String toMatch2 = "123$000000$12";   //Returns false
String toMatch3 = "0.0000$53$12";    //Returns false
String toMatch4 = "123$53$.000";     //Returns false

Essentially what I want is a Regex matching 3 numbers separated by the "$" character, with each number being a positive non-zero double if parsed by the Double.parseDouble() method.

Answer 1

If I've correctly understood, I think this will work:

^(?!\\$)((^|\\$)(?=[^$]*[1-9])(\\d+(\\.\\d*)?|(\\.\\d*)?\\d+)){3}$

Follows an explenation:

• ^(?!\\\\$) : the begin of the match must not be followed by a '$'
• {3} : the following pattern has to be repeated 3 times
  • (^|\\\\$) : the pattern starts or with the begin of the string or with a '$' (not both, for what stated above)
  • (?=[^$]*[1-9]) : before the next eventual '$' there must be a non-0 digit
  • (\\\\d+(\\\\.\\\\d*)?|(\\\\.\\\\d*)?\\\\d+) : the allowed format for the number is either \\d+(\\.\\d*)? or (\\.\\d*)?\\d+
• $ : end

See here for a demo

An extended expression (if you don't trust the repeat trick) is:

^(?=[^$]*[1-9])(\\d+(\\.\\d*)?|(\\.\\d*)?\\d+)\\$(?=[^$]*[1-9])(\\d+(\\.\\d*)?|(\\.\\d*)?\\d+)\\$(?=[^$]*[1-9])(\\d+(\\.\\d*)?|(\\.\\d*)?\\d+)$