Java regex Pattern matches doesn't recognise "Escape +" [duplicate]

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• Java Regex pattern that matches in any online tester but doesn't in Eclipse 1 answer

I was trying the pattern ^\\+[0-9]+ to match '+852(2)78911' but it seems that

Pattern.matches("^\\+[0-9]+", s)

is returning false. When I tried it in regexr it is working i.e. giving me a match. Am I not escaping this correctly in Java sense?