Java entry and faq _ 1 (3)

9. Display and format the date
Example:
Import java. util .*;
Import java. text .*;
Public class FormatDate {
Public static void main (String [] args ){
Date now = new Date ();
DateFormat defaultFormat = DateFormat. getDateInstance ();
DateFormat formatted format = DateFormat. getDateInstance (DateFormat. SHORT );
DateFormat mediumFormat = DateFormat. getDateInstance (DateFormat. MEDIUM );
DateFormat longFormat = DateFormat. getDateInstance (DateFormat. LONG );
DateFormat fullFormat = DateFormat. getDateInstance (DateFormat. FULL );
String defaultDate = defaultFormat. format (now );
String Updated Date = formatted format. format (now );
String mediumDate = mediumFormat. format (now );
String longDate = longFormat. format (now );
String fullDate = fullFormat. format (now );
System. out. println ("(Default) Today:" + defaultDate );
System. out. println ("(SHORT) Today:" + latest date );
System. out. println ("(MEDIUM) Today:" + mediumDate );
System. out. println ("(LONG) Today:" + longDate );
System. out. println ("(FULL) Today:" + fullDate );
}
}
The running result is:
D: javamail> java FormatDate
(Default) Today: 2003-6-15
(SHORT) Today: 03-6-15
(MEDIUM) Today: 2003-6-15
(LONG) Today: January 1, June 15, 2003
(FULL) Today: Sunday, January 1, June 15, 2003
10 What is the difference between static and non-static nested classes?
Static internal class meaning:
1. Create a static internal class object without an external class object
2. You cannot access an external class object from an object of a static internal class.
11. How can I determine whether the input is a character or a number?
Use Float. parseFloat (String data) to parse it
If NumberFormatException is thrown, it is not a number.
If you use StreamTokenizer, there is StreamTokenizer. ttype in it to determine whether it is a number.
You can also use Character. isDigit (char ch) to determine whether a Character is a number.
Character class method
Static boolean isDigit (char ch)
Determines if the specified character is a digit.
Static boolean isLetter (char ch)