Properties instead of public fields

A property looks like a value from outside and like a method inside. It is the polite way to expose data from a class.

A property in C#

public class Lesson
{
    private int minutes;

    public int Minutes
    {
        get { return minutes; }
        set
        {
            if (value >= 0)
            {
                minutes = value;
            }
        }
    }
}

Why not just a public field

• A property can reject a bad value, as the setter above rejects a negative number.
• A property can be read only or write only when that is the right rule.
• The storage can change later without breaking every caller.

When objects are no longer needed, the runtime reclaims them. That process is garbage collection.