DateFormat class

■ Numbering lines in a file. The sample program below numbers the lines and uses DateFormat to print out numbered lines from any file.

The pattern creates leading zeroes so the output lines appear as follows:

0001: line one

0002: line two

0003: line three

0004: line four etc.

import java.io.*;

import java.text.*;

class PrintNumberedLines {

public static void main(String args[ ]) {

try {

File fi = new File( "myinputfile" );

BufferedReader br = new BufferedReader( new FileReader( fi ));

PrintWriter pw = new PrintWriter( System.out, true);

String s;

double d = 1;

DecimalFormat pattern = new DecimalFormat( "0000" );

while ( ( s = br.readLine( )) != null ) {

pw.println( pattern.format( d++ ) + ": " + s );

}

br.close( );

pw.close( );

} catch (IOException e) { }

}

}

■ The sample class below shows various ways to format dates and times. Run it and see.

import java.util.*;

import java.text.*;

public class DateAndTimeExamples

{

// ( a ) Get a Date

Date d = new Date();

String s;

// ( b ) Get a DateFormat

DateFormat df;

public static void main(String[ ] args)

{ DateAndTimeExamples dt = new DateAndTimeExamples( ); }

public DateAndTimeExamples( )

{

// HOW TO USE THE PATTERNS

// ( c ) Get a SimpleDateFormat

SimpleDateFormat sdf;

// ( d ) Set it to a pattern

sdf = new SimpleDateFormat("MM.dd.yy");

// ( e ) Use it to format your date

s = sdf.format(d);

// WATCH the various numbered SYSPRINTs here. This is the first.

System.out.println("(1)\t " +d + "\n");

// ( f ) Set it to a formatter. DATES use getDateInstance

df = DateFormat.getDateInstance(DateFormat.DEFAULT);

// ( g ) Use it to format your date into a String

s = df.format(d);

System.out.println("(2)\t " +s + "\n");

df = DateFormat.getDateInstance(DateFormat.SHORT);

s = df.format(d);

System.out.println("(3)\t " +s + "\n");

df = DateFormat.getDateInstance(DateFormat.LONG);

s = df.format(d);

System.out.println("(4)\t " +s + "\n");

df = DateFormat.getDateInstance(DateFormat.FULL);

s = df.format(d);

System.out.println("(5)\t " +s + "\n");

df = DateFormat.getTimeInstance(DateFormat.SHORT);

s = df.format(d);

System.out.println("(6)\t " +s + "\n");

df = DateFormat.getTimeInstance(DateFormat.LONG);

s = df.format(d);

System.out.println("(7)\t " +s + "\n");

// DATE AND TIME use getDateTimeInstance(..)

df = DateFormat.getDateTimeInstance(DateFormat.DEFAULT,DateFormat.DEFAULT);

s = df.format(d);

System.out.println("(8)\t " +s + "\n");

df = DateFormat.getDateTimeInstance(DateFormat.SHORT,DateFormat.SHORT);

s = df.format(d);

System.out.println("(9)\t " +s + "\n");

df = DateFormat.getDateTimeInstance(DateFormat.LONG,DateFormat.LONG);

s = df.format(d);

System.out.println("(10)\t " +s + "\n");

df = DateFormat.getDateTimeInstance(DateFormat.FULL,DateFormat.FULL);

s = df.format(d);

System.out.println("(11)\t " +s + "\n");

s = sdf.format(d);

System.out.println("(12)\t " +s + "\n");

sdf = new SimpleDateFormat("'Minute' mm 'of Hour' kk 'of Day' D 'of Month' MM 'of Year' yyyy");

s = sdf.format(d);

System.out.println("(13)\t " +s + "\n");

sdf = new SimpleDateFormat("EEEE, MMMM dd, G yyyy");

s = sdf.format(d);

System.out.println("(14)\t " +s + "\n");

sdf = new SimpleDateFormat("a 'on a' EEEE 'in' MMMM");

s = sdf.format(d);

System.out.println("(15)\t " +s + "\n");

sdf = new SimpleDateFormat("MM.dd.yy k:mm:ss:SSS ");

s = sdf.format(d);

System.out.println("(16)\t " +s + "\n");

}

}//end class