[Quang Pham]

I'm Quang Pham, a computer science student at Palomar College. I'm having trouble developing a number systems conversion program in Java. This is what I've written so far:

/**
 * Write a description of class Decimal here.
 * 
 * @Quang Pham
 * @1/31/13
 */
import java.swing;

import java.util.Scanner;

public class Decimal
{
    
        public void getDec() 
        {
            String s1;
            s1 = JOptionPane.showInputDialog("Please enter the Decimal number you wish to convert.");
            Scanner in1 = new Scanner(s1);
            inDec = in1.nextInt();
        }
        public void toBin();  
        public void toHex();  
        public void outBin();
        public void outHex(); 
    
}

Does anybody know how to make the conversions? Thanks for any help.

[Martyr2]

I suppose you are not allowed to use the toHexString()/toBinaryString()/toOctalString() functions?

[Quang Pham]

Thanks for giving me the functions idea. I will ask the instructor, but I think he said that we couldn't. This would be a faster method. Thanks for your reply to my guestion.

[macosxnerd101]

Check out NeoTifa's tutorial Number Systems for Beginners.

[Quang Pham]

Thanks for the reference to the tutorial. It was very helpful. Now I need to put it into Java code. I need to convert decimal, binary, and hexadecimal, writing in Java code.

Thanks for the reference to the tutorial. It was very helpful. Now I need to put it into Java code. I need to convert decimal, binary, and hexadecimal, writing in Java code.

[macosxnerd101]

Glad I could help! Good luck!

[Quang Pham]

Thank you for your replies for my number systems conversion question. This is the code I have developed so far.

/**
 * Converts decimal numbers to binary and hexadecimal.
 * 
 * @Quang Pham
 * @1/31/13
 */
import javax.swing.*;

import java.util.Scanner;

//public class LineWriter()
//{
//}

public class Decimal

{
    LineWriter lw;
    public Decimal (LineWriter lw)
    {
     lw = new LineWriter("csis.txt");   
    }
    

    int inDec;
    String Bin;
    String Hex;
    int number;
    int remainder;
    char digit;
    char A,B,C,D,E,F;

    public void getDec()
    {

        String s1;
        s1 = JOptionPane.showInputDialog("Please enter the Decimal number you wish to convert.");
        Scanner in1 = new Scanner(s1);
        inDec = in1.nextInt();
        number = inDec;
        System.out.println(" ");
    }

    public void DecToBin()
    {
        int i;
        String Bin = "";
        String reversednumber = "";
        
        while (number != 0)
        {
            remainder = number % 2;
            number = number / 2; 
            Bin = Bin + remainder;
            
           
            
            if(remainder > 0)
            {System.out.print ("1");}
            else 
            {System.out.print ("0");}
        } 
        
        for (i = Bin.length()-1; i >= 0; i--)
            reversednumber = reversednumber + Bin.charAt(i);
            
        Bin = reversednumber;
        
        System.out.println ("");
        System.out.println (("The decimal entry is:  ") + inDec);
        System.out.println (("The binary conversion is:  ") + Bin);
    }  

    public void DecToHex()
    {
        int i;
        int digit = 0;
        String Hex = "";
        String reversednumber = "";
        
        while (number != 0)
        {
            remainder = number % 16;
            number = number / 16;
            
            if (remainder == 1) {digit = 1;}
            if (remainder == 2) {digit = 2;}
            if (remainder == 3) {digit = 3;}
            if (remainder == 4) {digit = 4;}
            if (remainder == 5) {digit = 5;}
            if (remainder == 6) {digit = 6;}
            if (remainder == 7) {digit = 7;}
            if (remainder == 8) {digit = 8;}
            if (remainder == 9) {digit = 9;}
            if (remainder == 10) {digit = A;}
            if (remainder == 11) {digit = B;}
            if (remainder == 12) {digit = C;}
            if (remainder == 13) {digit = D;}
            if (remainder == 14) {digit = E;}
            if (remainder == 15) {digit = F;}
            Hex = Hex + digit;
            
            for (i = Hex.length()-1; i >= 0; i--)
            reversednumber = reversednumber + Hex.charAt(i);
            
            Hex = reversednumber;
            
        }  
         System.out.println (("The decimal entry is:  ") + inDec);
         System.out.println (("The hexadecimal conversion is:  ") + Hex);
    }

    public void outBin()
    {
        System.out.println (inDec);
        System.out.println (Bin);
    }

    public void outHex()
    {
        System.out.println (inDec);
        System.out.println (Hex);
    }

}

I'm still working on my binary and hexadecimal conversions.

[pbl]

           if(remainder > 0)  
             {System.out.print ("1");}  
           else  
             {System.out.print ("0");}  

and

            if (remainder == 1) {digit = 1;}
            if (remainder == 2) {digit = 2;}
            if (remainder == 3) {digit = 3;}
            if (remainder == 4) {digit = 4;}
            if (remainder == 5) {digit = 5;}
            if (remainder == 6) {digit = 6;}
            if (remainder == 7) {digit = 7;}
            if (remainder == 8) {digit = 8;}
            if (remainder == 9) {digit = 9;}
            if (remainder == 10) {digit = A;}
            if (remainder == 11) {digit = B;}
            if (remainder == 12) {digit = C;}
            if (remainder == 13) {digit = D;}
            if (remainder == 14) {digit = E;}
            if (remainder == 15) {digit = F;}

What will you do with this when they wil;l ask you to convert to base 64 ?
use

   String num = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
   digit = num.chatAt(remainder);

it will work for any base from 2 to 36

[Quang Pham]

I am having a problem with the decimal to hexadecimal conversion. Only the Java library code seems to work so far. Do you see something wrong with the decimal to hexadecimal code?

/**
 * Converts decimal to binary and hexadecimal numbers.
 * 
 * @Quang Pham
 * @1/31/13
 */
import javax.swing.*;

import java.util.Scanner;

public class Decimal

{
    LineWriter lw;
    public Decimal (LineWriter lw)
    {
        lw = new LineWriter("csis.txt");   
    }

    int inDec;
    String Bin;
    String Hex;
    int number;
    int remainder;
    
    public void getDec()
    {

        String s1;
        s1 = JOptionPane.showInputDialog("Please enter the Decimal number you wish to convert.");
        Scanner in1 = new Scanner(s1);
        inDec = in1.nextInt();
        number = inDec;
        System.out.println(" ");
    }

    public void DecToBin()
    {
        int i;
        String Bin = "";
        String reversednumber = "";

        while (number != 0)
        {
            remainder = number % 2;
            number = number / 2; 
            Bin = Bin + remainder;

            
            if(remainder > 0)
            {System.out.print ("1");}
            else 
            {System.out.print ("0");}
        } 

        for (i = Bin.length()-1; i >= 0; i--)
            reversednumber = reversednumber + Bin.charAt(i);

        Bin = reversednumber;

        System.out.println ("");
        System.out.println (("The decimal entry is:  ") + inDec);
        System.out.println (("The binary conversion is:  ") + Bin);
    }  

    public void DecToHex()
    {
        String Hex = "";
        int dec = 0;
        int remainder = 0;
        int i = 0;
        int j = 0;
        String reversednumber = "";
        char[] HexDigit = {'0', '1', '2', '3', '4', '5', '6' , '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
        char A = 'a'; char B = 'b'; char C = 'c'; char D = 'd'; char E ='e'; char F = 'f';

        while (number != 0)
        {
            remainder = number % 16;
            number = number / 16;
            
            if (remainder == 1)  HexDigit[0] = 0;
            if (remainder == 2)  HexDigit[1] = 1;
            if (remainder == 3)  HexDigit[2] = 2;
            if (remainder == 4)  HexDigit[3] = 3;
            if (remainder == 5)  HexDigit[4] = 4;
            if (remainder == 6)  HexDigit[5] = 5;
            if (remainder == 7)  HexDigit[6] = 6;
            if (remainder == 8)  HexDigit[7] = 7;
            if (remainder == 9)  HexDigit[8] = 8;
            if (remainder == 10) HexDigit[9] = 9;
            if (remainder == 11) HexDigit[10] = A;
            if (remainder == 12) HexDigit[11] = B;
            if (remainder == 13) HexDigit[12] = C;
            if (remainder == 14) HexDigit[13] = D;
            if (remainder == 15) HexDigit[14] = E;            
            if (remainder == 16) HexDigit[15] = F;

            Hex = Hex + HexDigit[j];

        }  

        for (i = Hex.length()-1; i >= 0; i--)
            reversednumber = reversednumber + Hex.charAt(i);

        Hex = reversednumber;
        dec = inDec;
        
        String hex = Integer.toHexString(dec);

        System.out.println (("The decimal entry is:  ") + inDec);
        System.out.println (("The hexadecimal conversion is:  ") + Hex);
        System.out.println (("The hexadecimal conversion is (using library method):  ") + hex);
    }

    public void outBin()
    {
        System.out.println (inDec);
        System.out.println (Bin);
    }

    public void outHex()
    {
        System.out.println (inDec);
        System.out.println (Hex);
    }

}

Thanks for any suggestions about the decimal to hexadecimal conversion.

*Edited: please

This post has been edited by pbl: 22 February 2013 - 03:59 PM
Reason for edit:: Fixed code tags

[pbl]

Did you read the solutions we posted ?

To convert from binary (which is the base used by any number on a computer) you simply:

n = number % base;
number /= base;
char asciiRepresentation = num.charAt(n);