pattern.matcher() vs pattern.matches()

Question

I am wondering why the results of the java regex pattern.matcher() and pattern.matches() differ when provided the same regular expression and same string

Answer 1

matches tries to match the expression against the entire string. Meaning, it checks whether the entire string is a patern or not. conceptually think it like this, it implicitly adds a ^ at the start and $ at the end of your pattern.

For, String str = "hello+", if you want matches() to return true, you need to have pattern like ".\+."

I hope this answered your question.