/**

* Write a method call toRadix() which converts a positive integer from one radix into another.

* The method has the following header:

*

* public static String toRadix(String in, int inRadix, int outRadix) // The input and output are treated as String.

*

* Write a program called NumberConversion, which prompts the user for an input number,

* an input radix, and an output radix, and display the converted number.

* The output shall look like:

* Enter a number and radix: A1B2

* Enter the input radix: 16

* Enter the output radix: 2

* "A1B2" in radix 16 is "1010000110110010" in radix 2.

*/

package javaexercises.difficult;

public class NumberConversion {

private final String alphabet = "0123456789ABCDEFGHIJKLMNOPQRSTVUWXYZ";

public static void main(String[] args)

{

NumberConversion aNumberConversion = new NumberConversion();

String numberStr = "01010101";

int inRadix = 2;

int outRadix = 10;

System.out.printf("\"%1$s\" in radix %2$d is \"%3$s\" in radix %4$d.\n"

, numberStr, inRadix

, aNumberConversion.toRadix(numberStr, inRadix, outRadix), outRadix

);

}

private int toInt(String in, int inRadix)

{

int result = 0;

for(int i = in.length()-1; i >= 0; i--) {

int digit = Character.digit(in.charAt(i), inRadix);

result += digit * Math.pow(inRadix, (in.length()-1 - i));

}

return result;

}

private String toRadix(int number, int radix)

{

String result = "";

if (radix == 0) {

return result;

}

while (number > 0) {

result = alphabet.charAt(number%radix) + result;

number /= radix;

}

return result;

}

private String toRadix(String in, int inRadix, int outRadix) {

if (inRadix == outRadix) {

return in;

}

return toRadix(toInt(in, inRadix), outRadix);

}

}