Number System in java

Write an application that prints a table of the binary, octal, and hexadecimal equivalents of
the decimal numbers in the range 1 through 256. If you are not familiar with these number systems, read Appendix C first. Place the results in a JTextArea with scrolling functionality. Display the JTextArea in a message dialog.

ANS:

import javax.swing.*;
public class NumberSystem {

public static void main( String args[] )
 {
 // create a scrolled pane for the output
JTextArea outputTextArea = new JTextArea( 15, 35 );
JScrollPane scroller = new JScrollPane( outputTextArea );
outputTextArea.append( "\nDecimal\tBinary\tOctal\tHexadecimal\n" );

 // print out binary, octal and hexadecimal representation
 // for each number
for ( int i = 1; i <= 256; i++ ) {
 int decimal = i;
 String binary = "", octal = "", hexadecimal = "";
 int temp;

 // get binary representation
 while ( decimal >= 2 ) {
 temp = decimal % 2;
 binary = temp + binary;
 decimal /= 2;
 }
 binary = decimal + binary;

decimal = i;

 // get octal representation
 while ( decimal >= 8 ) {
 temp = decimal % 8;
 octal = temp + octal;
 decimal /= 8;
 }
octal = decimal + octal;

 decimal = i;

 // get hexadecimal representation
 while ( decimal >= 16 ) {
 temp = decimal % 16;

switch ( temp ) {
 case 10:
hexadecimal = "A" + hexadecimal;
 break;
 case 11:
hexadecimal = "B" + hexadecimal;
 break;
 case 12:
hexadecimal = "C" + hexadecimal;
 break;
 case 13:
hexadecimal = "D" + hexadecimal;
 break;
case 14:
hexadecimal = "E" + hexadecimal;
 break;
 case 15:
 hexadecimal = "F" + hexadecimal;
 break;
default:
hexadecimal = temp + hexadecimal;
 break;
 }
 decimal /= 16;
 }
 switch ( decimal ) 

{
 case 10:
hexadecimal = "A" + hexadecimal;
 break;
case 11:
hexadecimal = "B" + hexadecimal;
 break;
case 12:
hexadecimal = "C" + hexadecimal;
break;
case 13:
 hexadecimal = "D" + hexadecimal;
 break;
 case 14:
 hexadecimal = "E" + hexadecimal;
 break;
 case 15:
 hexadecimal = "F" + hexadecimal;
 break;
 default:
 hexadecimal = decimal + hexadecimal;
 break;
 }
 outputTextArea.append( i + "\t" + binary + "\t" + octal + "\t" + hexadecimal + "\n" );
 }
 // show result
 JOptionPane.showMessageDialog( null, scroller,
 "Number System", JOptionPane.INFORMATION_MESSAGE );
// terminate the application
System.exit( 0 );
}
} // end class NumberSystem