220: Highlights

• Constructors perform computations, such as instance-variable assignment, that you want to occur when your program creates an instance.
• Each constructor is named for the class in which it is defined. All constructors return class instances.
• In the absence of any constructors defined by you, Java creates a default constructor, which has no parameters.
• If you want to define a zero-parameter constructor to displace the default constructor, then instantiate the following pattern:

  public class name () { 
   ... 
  } 
  

• If you want to define a constructor with parameters, then instantiate the following pattern:

  public class name (parameter specifications) { 
   ... 
  } 
  

• When you create instances, the number and types of the arguments that you supply determine which constructor is called.