Class Binary

  • public class Binary
extends Object
    A class that represents a binary (base-2) number. A binary number is made up of one or more binary digits called bits. A bit has a value that is equal to either 0 or 1. An 8-bit binary number is shown below.

    A Binary number owns the individual bits.

    To convert a binary number to its decimal (base-10) equivalent, each bit is multiplied by an increasing power of 2 starting from the right-most bit. For example, the decimal equivalent of the 8-bit binary number can be calculated as (1 * 128) + (0 * 64) + (0 * 32) + (1 * 16) + (0 * 8) + (1 * 4) + (1 * 2) + (1 * 1) = 151:

    The decimal equivalent of the 3-bit binary number can be calculated as (1 * 4) + (1 * 2) + (1 * 1) = 7:

    • Constructor Summary

      Constructors 
      Constructor Description
      Binary​(Binary other)
      Initializes this binary number by copying the bits from another binary number.
      Binary​(List<Bit> bits)
      Initializes this binary number to have the specified bits.

    • Constructor Detail

      • Binary

        public Binary​(List<Bit> bits)
        Initializes this binary number to have the specified bits. The constructor copies the individual bits into this binary number.
        Parameters:
        bits - the bits of the binary number
        Throws:
        IllegalArgumentException - if bits.size() is less than 1

      • Binary

        public Binary​(Binary other)
        Initializes this binary number by copying the bits from another binary number.
        Parameters:
        other - the binary number to copy

    • Method Detail

      • numberOfBits

        public int numberOfBits()
        Returns the number of bits in this binary number.
        Returns:
        the number of bits in this binary number

      • getLeftMostBit

        public Bit getLeftMostBit()
        Returns the left-most bit of this binary number. The returned Bit cannot be used to modify this binary number.
        Returns:
        the left-most bit of this binary number

      • getRightMostBit

        public Bit getRightMostBit()
        Returns the right-most bit of this binary number. The returned Bit cannot be used to modify this binary number.
        Returns:
        the right-most bit of this binary number

      • setBit

        public void setBit​(int index,
                   Bit bit)
        Sets a bit at the given index by copying the value of bit into the bit at the given index.

        Index 0 is the index of the left-most bit.

        Parameters:
        index - the index of the bit to set
        bit - the value of the bit to set
        Throws:
        IllegalArgumentException - if index is out of bounds for this binary number

      • equals

        public boolean equals​(Object obj)
        Compares this binary number to an object for equality. Returns true if and only if obj is a Binary number that represents the same decimal value as this number.

        This method does not use toDecimal to compare the binary numbers. Instead, it makes a copy of the binary number with the fewest number of bits and adds enough zeros to the front of the copied number so that the copied number has the same number of bits as this number; then the binary representation of this number and the copied number are compared for equality. For example if this binary number has the 6-digit representation:

        000011

        and the other binary number has the 3-digit representation:

        011

        then a copy of the shorter number is padded with 3 zeros to become:

        000011

        which has the same binary representation as this number.

        Overrides:
        equals in class Object
        Parameters:
        obj - the object to compare
        Returns:
        true if this binary number is equal to the other binary number, false otherwise

      • toDecimal

        public int toDecimal()
        Returns the decimal (base 10) value of this binary number as an int value. If this binary number has 32 bits or more then the user of this method should expect that the result will be incorrect because of overflow.
        Returns:
        the decimal (base 10) value of this binary number

      • toDecimalHelper

        static int toDecimalHelper​(List<Bit> bits)
        Recursively computes the decimal value of a binary number represented as a list of bits. For example, the list:

        [1, 0, 1, 1]

        representing the binary number 1011 has a decimal value of

        (1 * 2^3) + (0 * 2^2) + (1 * 2^1) + (1 * 2^0) = 11

        If this binary number has 32 bits or more then the user of this method should expect that the result will be incorrect because of overflow.

        Parameters:
        bits - a list of bits representing a binary number
        Returns:
        the decimal value of the binary number

      • toString

        public String toString()
        Returns a string representation of this binary number. The returned string is made up of the bit values (0 or 1) of the number from the left-most bit to the right-most bit.
        Overrides:
        toString in class Object
        Returns:
        a string representation of this binary number

      • hashCode

        public int hashCode()
        Returns a hash code for this binary number.
        Overrides:
        hashCode in class Object
        Returns:
        a hash code for this binary number

      • getBits

        public List<Bit> getBits()
        Returns a reference to the list of bits; for testing purposes only.
        Returns:
        a reference to the list of bits of this binary number

      • main

        public static void main​(String[] args)
        A simple test method.
        Parameters:
        args - not used