excel - How to check the date is in US format in java -

the user enters date follows:

20/05/2015

now know in format date invalid. how check in java? in code date value excel sheet , how i'm processing it. date read excel sheet numerical. example-3124.0 i.e., no. of days passed since 1/1/1990. converting format mm/dd/yyy:

simpledateformat sdf = new simpledateformat("mm/dd/yyyy"); string s = sdf.format(cell.getdatecellvalue()); 

format method of simpledateformat takes in date parameter. hence cell.getdatecellvalue() gives date type value passed format method converts string value.

 simpledateformat sdf = new simpledateformat("mm/dd/yyyy");  string s = sdf.format(cell.getdatecellvalue());  system.out.println(s);     sdf.setlenient(false);  date d=    sdf.parse(s);  system.out.println(sdf.format(d)); 

so if excel cell value 12/08/2015

system.out.println(s);  // prints 12/08/2015  system.out.println(sdf.format(d)); //prints 12/28/2015 

don't understand.

if date comes string can try regex:

    string date ="20/11/2015";        private static final string date_pattern =         "(0?[1-9]|1[012])/(0?[1-9]|[12][0-9]|3[01])/((19|20)\\d\\d)";      pattern = pattern.compile(date_pattern);     matcher = pattern.matcher(date);     if(matcher.matches()){         system.out.println("mateched");     }else {         system.out.println("not matched");     } 

if have more once, make pattern static , compile once (in constructor or static block probably).