android - why string.matches and pattern.matches get different results? -

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 // pattern 20xx/xx/xx, e.g. 2012/2/22 string regex_date_1 = "20\\d\\d/\\d{1,2}/\\d{1,2}";  string cell = "from 2011/7/31 2011/8/15 15:10-17:40,18:30-21:00"; system.out.println(cell);  system.out.println("--- ---"); system.out.println( cell.matches(regex_date_1) );  system.out.println("--- b ---"); pattern p = pattern.compile(regex_date_1); matcher m = p.matcher(cell); while(m.find()){     system.out.println( m.group(0) ); }

results:

 2011/7/31 2011/8/15 15:10-17:40,18:30-21:00 --- --- false --- b --- 2011/7/31 2011/8/15

why string.matches return false? pattern.matches can matches?

because string#matches return true "if, , if, string matches given regular expression". can check documentation here : string#matches

however matcher#find return true " if, , if, subsequence of input sequence matches matcher's pattern". documentation available here : matcher#find.

so sum - string#matches returns true if whole string matched regex , matcher#find returns true if subsequence of string can matched regex.


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