What Parts of an Object can be Seen?

The dot operator is how you access a part of an object:

referenceToAnObject . partOfTheObject

Of course, an object has to exist, and there has to be a reference to it. In the program, this happened when the object was constructed:

CheckingAccount account1 
        = new CheckingAccount( "123", "Bob", 100 );

When a method has a reference to an object, the method can:

1. access the object's instance variables using dot notation, and
2. call the object's methods using dot notation.

However, it is common for a class to have private variables and methods. Only methods of the class can access these. This will be discussed further in the next chapter.

To begin with, our programs will look like the following, all in one source file:

class SomeClass
{
  instance variables, constructors, and methods

}

class  TesterClass
{
  public static void main ( String[] args )
  {
    SomeClass someObject = new SomeClass( . . .  );

    someObject . instanceVariable = . . .;
    someObject . method( ... ) ;

    . . .

  }
}