Nullary constructor

In computer programming, a nullary constructor is a constructor that takes no arguments.

Java example

public class Example 
{
   /* '''nullary constructor''' */
   public Example () {
      this(1);
   }

   /* non-nullary constructor */
   public Example (int data) {
      this.data = data;
   }

   protected int data;
}

Haskell example

-- nullary type constructor with two nullary data constructors
data Bool = False
          | True

-- non-nullary type constructor with non-nullary data constructor
data Point a = Point a a

-- nun-nullary type constructor with...
data Maybe a = Nothing  -- ...nullary data constructor
             | Just a   -- ...unary data constructor