Binary to Hexadecimal Conversion

Hello! I made this program of converting binary to hexadecimal, there
are few errors which are new to me. Please check it out. Thanks!

<code>

import java.lang.*;
import java.io.*;

class BinaryDecoder{
    public static void main(String args[]) throws IOException{
        InputStreamReader stdin = new InputStreamReader(System.in);
        BufferedReader console = new BufferedReader(stdin);
        System.out.print("Enter a number in binary: ");
        String input = console.readLine();

        int decimal=0;
        for(int counter=input.length()-1; counter>=0; counter--){
            if(input.charAt(counter)=='1'){
                int exp=input.length()-1-counter;
                decimal+=Math.pow(2,exp);
            }
        }

        int hexadecimal=0;
        int powerOfTen=1;
        int number=decimal;
        int counter=0;
        int[] hex = new int[20];

        while(number>0){
            int remainder=number%16;
            hex[counter] = remainder;
            counter++;
            number/=16;
        }

        System.out.print("Hexadecimal: ");
        for(int count=hex.length; count>=0; count--){
            if(hex[count]==10)
                System.out.print("A");
            else if(hex[count]==11)
                System.out.print("B");
            else if(hex[count]==12)
                System.out.print("C");
            else if(hex[count]==13)
                System.out.print("D");
            else if(hex[count]==14)
                System.out.print("E");
            else if(hex[count]==15)
                System.out.print("F");
            else
                System.out.print(hex[count]);
        }
    }
}

</code>