Convert from Decimal to Binary, Octal or Hex in Java using Integer.toXXXString(int)

Integer class does provide lots of unitily methods to be consumed directly

Integer decimal1 = 21;

System.out.println(decimal1 + "=" + Integer.toBinaryString(decimal1));

Integer decimal2 = 302;

System.out.println(decimal2 + "=" + Integer.toOctalString(decimal2));

Integer decimal3 = 43981;

System.out.println(decimal3 + "=" + Integer.toHexString(decimal3));

Output:

21 = 10101

302 = 456

43981 = abcd