查找两个“ /”之间的子字符串

Question

For this program the user is told to input a data in the form of "mm/dd/yyyy" and I'm trying to use the indexOf() method with the parameter of "/" to break the date string into three substrings.

I tried doing this:

String monthString = dateString.substring(0,dateString.indexOf("/"));
    String dayString = 
    dateString.substring(dateString.indexOf("/"),DateString.indexOf("/")+1)

Thank you. Edit. Thank you all for your responses, but my teacher said that i cannot use the split fucntion. He said I can solve this using just indexOf("/") and substring(). I'll need two calls to indexOf("/") and four calls to substring().

Answer 1

String[] element = dateString.split("/");
String strDay = element[0];
String strMonth = element[1];
String strYear = element[2];

This is what you're looking for.

Answer 2

Instead of split() method you can use Java Date API

  String dateString = "10/30/2018";
    try {
        DateFormat dateFromatter = new SimpleDateFormat("MM/dd/yyyy");
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(dateFromatter.parse(dateString));
        System.out.println("Date:" + calendar.get(Calendar.DATE));
        System.out.println("Month:" + calendar.get(Calendar.MONTH));
        System.out.println("Year:" + calendar.get(Calendar.YEAR));
    } catch (Exception e) {
        e.printStackTrace();
    }

Output

Date:30
Month:9
Year:2018

For month field Calendar.MONTH starts from 0 which mean Jan=0,Feb=1 Refer Java Doc

Answer 3

dateString.split("[/]"); gives you the array of string. split() function take input in regex thats why "[]" are added.

if the dateString is "dd/mm/yy" then dateString.split("[/]") return the String array consists of {"dd","mm","yy"} .

Answer 4

If you are using Java 8 or above and actually you are handling date and time , then I think you should have a try at LocalDate.parse and as to your problem then you can achieve it easily as:

LocalDate theDate = LocalDate.parse("08/22/2018", DateTimeFormatter.ofPattern("MM/d/yyyy"));
System.out.println("year: " + theDate.getYear() + " month: " + theDate.getMonthValue() + " day: " + theDate.getDayOfMonth());

the output will be:

year: 2018 month: 8 day: 22