使用 Scanner 在 Java 中读取日期

Question

Well, i'm trying to read a string with scanner in the same line. For exapme ,i want to read: Monday 12 December 2013 and this needs to be put in a String variable so as to help me print it.

In my code there is this:

sale.setDate(sc.next());

with the command sc.next() i can't put a date in the form i mentioned but only in a form like: mmddyy or mm/dd/yyyy

How can i read a whole string like "Monday 12 December 2013 " ?

There is a confusion for me about sc.next sc.nextLine etc..

Answer 1

For scanner:http://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html The next() and hasNext() methods first skip any input that matches the delimiter pattern, and then attempt to return the next token. nextLine advances this scanner past the current line and returns the input that was skipped.

Use a date DateFormat to parse string to date; I suppose setDate expects a Date

    Scanner scanner = new Scanner("Monday 12 December 2013,a, other fields");
    scanner.useDelimiter(",");

    String dateString = scanner.next();
    //System.out.println(dateString);

    DateFormat formatter = new SimpleDateFormat("EEEE dd MMM yyyy");
    Date date = formatter.parse(dateString);
    //System.out.println(date);
    sale.setDate(sc.next()); 

Answer 2

Even i faced the same issue but after that able to resolve with below mentioned code. Hope it helps.

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.Scanner;

public class Datinput {

    public static void main(String args[]) {
        int n;
        ArrayList<String> al = new ArrayList<String>();
        Scanner in = new Scanner(System.in);
        n = in.nextInt();
        String da[] = new String[n];
        SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
        sdf.setLenient(false);
        Date date[] = new Date[n];
        in.nextLine();
        for (int i = 0; i < da.length; i++) {
            da[i] = in.nextLine();
        }
        for (int i = 0; i < da.length; i++) {

            try {
                date[i] = sdf.parse(da[i]);
            } catch (ParseException e) {

                e.printStackTrace();
            }
        }

        in.close();
    }
}

Answer 3

Another way to do this is by utilizing LocalDateTime and DateTimeFormatter from Java 8. Found this example here :

DateTimeFormatter formatter = DateTimeFormatter.ofPattern(yyyy-MM-dd HH:mm:ss.SSS);
LocalDateTime dateTime = LocalDateTime.parse(s.next(), formatter);
System.out.println(dateTime.format(formatter));

Check the link for an in-depth explanation!

Answer 4

Try this..

public void readDate() throws Exception{
    String dateFormat = "dd/MM/yyyy";
    Scanner scanner = new Scanner(System.in);
    setDate(new SimpleDateFormat(dateFormat).parse(scanner.nextLine()));
}
public void setDate(Date date){
    // do stuff
}

chage the dateFormat as you want..

Answer 5

You have to use nextLine to fetch words with intermediate spaces.

next() can read the input only till the space. It can't read two words separated by space. Also, next() places the cursor in the same line after reading the input.

nextLine() reads input including space between the words (that is, it reads till the end of line \\n). Once the input is read, nextLine() positions the cursor in the next line.

Scanner sc=new Scanner(System.in);
System.out.println("enter string for c");
String c=sc.next();
System.out.println("c is "+c);
System.out.println("enter string for d");
String d=sc.next();
System.out.println("d is "+d);

OUTPUT:

enter string for c
abc def             
c is abc  
enter string for d
d is  defabc def| 

in the first case abc |def //cursor stays after c

in the second case abc def| //cursor stays after for

Answer 6

I found this question interesting but there is not a fully correct answer, so here is a simple solution to easily read and parse a Date form the Scanner .

The best approch would be to create a method that would do it for you, since Scanner is final, we can only do a toolbox instead of a subclass. But this would be easy to use :

public static Date readDate(Scanner sc, String format){
     return new SimpleDateFormat(format).parse(sc.nextLine());
}

This would accept the format and the Scanner, don't manage it here because it would be messy to open a Scanner without closing it (but if you close it, you can't open it again).

Scanner sc = new Scanner(System.in);
ToolBox.readDate(sc, "YYYY-MM-DD");
ToolBox.readDate(sc, "YYYY-MM-DD HH:mm:ss");
ToolBox.readDate(sc, "YYYY-MM-DD");
sc.close();

This could be improved by not recreating a SimpleDateFormat each time but a Scanner is not called that much (you are limit by the user inputs) so this is not that important.

Answer 7

try this one

final Scanner sc = new Scanner(System.in);
final String timeString = sc.next();
final LocalTime time = LocalTime.parse(timeString);