jAva programming

Write a code to input a binary number and convert it to a decimal number. For example: ex. 1 - 1111 in decimal is 1*(243) +1*(2^2)+1*(2^1) +1*(240) = 8 + 4 + 2 + 1 = 15 in decimal. ex.2 - 10101 in decimal is 1*(244) +0*(243) +1*(2^2) +0*(2^1) +1*(240) = 16 + 0 + 4 + 0 + 1 = 21 in decimal. The number of digits to be entered by the user in the binary number has no fixed size input (user can enter any number of bits). Sample Output: Enter the binary number 1 1 0 1 The decimal number is: 13