/// <summary>
/// This method adds the given Income object in the end of the List.
/// </summary>
/// <param name="task"></param>
public void Add(Income income)
{
incomeList.Add(income);
incomeList.Sort((x, y) => x.Date.CompareTo(y.Date));
}
/// <summary>
/// This method changes the Income object with a new one.
/// </summary>
/// <param name="index"></param>
/// <param name="newIncome"></param>
public void Edit(int index, Income newIncome)
{
incomeList[index] = newIncome;
incomeList.Sort((x, y) => x.Date.CompareTo(y.Date));
}