RegEx for matching specific upper and lower case patterns

Question

I need to check correctness of input string using regex pattern, every word should start with capital letter, also at the end there could be expression separated with "-". String should contain at least two words or expression with dash.

e.g.

correct:

• Apple Banana Couonut-Dates

• Apple Banana

• Banana Couonut-Dates

• Couonut-Dates

incorrect:

• Apple

• Apple Banana Couonut-dates

• BanAna couonut-Dates

Pattern pattern = Pattern.compile("([A-Z][a-z]++ )*([A-Z][a-z]++-[A-Z][a-z]++)");
pattern.matcher("Apple Banana Couonut-Dates").matches();

For input "Apple Banana Couonut-Dates" my expression returns false

Answer 1

To match at least 2 uppercase words with an optional part with expression separated with - at the end or a single expression separated with - you might use:

^(?:[A-Z][a-z]+(?: [A-Z][a-z]+\b(?!-))+(?: [A-Z][a-z]+-[A-Z][a-z]+)?|(?:[A-Z][a-z]+ )?[A-Z][a-z]+-[A-Z][a-z]+)$

• ^ Start of string
• (?:Non capturing group
  • [A-Z][a-z]+ Match uppercased word
  • (?: [A-Z][a-z]+\b(?!-))+ Repeat 1+ times uppercased word asserting what is on the right is not a -
  • (?: [A-Z][a-z]+-[A-Z][a-z]+)? Optional part, match space and uppercaseword-uppercase word
  • | Or
  • (?:[A-Z][a-z]+ )? Match optional uppercased word with space
  • [A-Z][a-z]+-[A-Z][a-z]+
• )$ End of string

Regex demo

Note in Java to double escape the backslash.