Write a program to convert a decimal number into hexadecimal number system.

import java.io.*;
public class DecToHex
{
    public static void main(String [] args)throws IOException
    {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        System.out.println("Enter Decimal Number");
        int a = Integer.parseInt(br.readLine());
        int n=0,r=0;
        String str ="";
        while(a>0)
        {
            r=a%16;
            //System.out.println(r);
            a=a/16;
            if(r>=0&&r<=9)
            {
                str = String.valueOf(r)+str;
            }
            if(r==10)
            {
                str = "A"+str;
            }
            if(r==11)
            {
                str = "B"+str;
            }
            if(r==12)
            {
                str = "C"+str;
            }
            if(r==13)
            {
                str = "D"+str;
            }
            if(r==14)
            {
                str = "E"+str;
            }
            if(r==15)
            {
                str = "F"+str;
            }
        }
        System.out.println(str);
  }
}