Money.java

//Denisolt Shakhbulatov
public class Money
{
    private long dollars;
    private long cents;
    public Money(double amount)
    {
        if (amount < 0)
        {
            System.out.println("Error: Negative amounts of money are not allowed.");
            System.exit(0);
        }
        else
        {
            long allCents = Math.round(amount*100);
            dollars = allCents/100;
            cents = allCents%100;
        }
    }

    public Money(Money obj1)
    {
        dollars = obj1.dollars;
        cents = obj1.cents;
    }

    /**Adds the calling Money object to the parameter Money object.
    @param otherAmount the amount of money to add
    @return the sum of the calling Money object and the parameter Money object*/
    public Money add(Money otherAmount)
    {
        Money sum = new Money(0);
        sum.cents = this.cents + otherAmount.cents;
        long carryDollars = sum.cents/100;
        sum.cents = sum.cents%100;
        sum.dollars = this.dollars
        + otherAmount.dollars + carryDollars;
        return sum;
    }

    /**Subtracts the parameter Money object from the calling Money
    object and returns the difference.
    @param amount the amount of money to subtract
    @return the difference between the calling Money object and the
    parameter Money object*/
    public Money subtract (Money amount)
    {
        Money difference = new Money(0);
        if (this.cents < amount.cents)
        {
            this.dollars = this.dollars - 1;
            this.cents = this.cents + 100;
        }
        difference.dollars = this.dollars - amount.dollars;
        difference.cents = this.cents - amount.cents;
        return difference;
    }

    /**Compares instance variable of the calling object with the
    parameter object.  It returns -1 if the dollars and the cents
    of the calling object are less than the dollars and the cents
    of the parameter object, 0 if the dollars and the cents of the
    calling object are equal to the dollars and cents of the
    parameter object, and 1 if the dollars and the cents of the
    calling object are more than the dollars and the cents of the
    parameter object.
    @param amount the amount of money to compare against
    @return -1 if the dollars and the cents of the calling object are
    less than the dollars and the cents of the parameter object, 0 if
    the dollars and the cents of the calling object are equal to the
    dollars and cents of the parameter object, and 1 if the dollars
    and the cents of the calling object are more than the dollars and
    the cents of the parameter object.*/
    public int compareTo(Money amount)
    {
        int value;
        if(this.dollars < amount.dollars)
        {
            value = -1;
        }
        else if (this.dollars > amount.dollars)
        {
            value = 1;
        }
        else if (this.cents < amount.cents)
        {
            value = -1;
        }
        else if (this.cents > amount.cents)
        {
            value = 1;
        }
        else
        {
            value = 0;
        }
        return value;
    }

    public boolean equals(Money otherObject)
    {
        if((dollars==otherObject.dollars)&&(cents==otherObject.cents))
            return true;
        else
            return false;
    }

    public String toString()
    {
        String str = "";
        if (cents>10)
            str = "$" + dollars + "." + cents;
        else 
            str = "$" + dollars + ".0" + cents;
        return str;
    }

}