15. Using the this keyword

• The this keyword has meaning only within a class definition.

• Four possible uses of the this keyword are:

  
  // refer to an instance variable of the current object
  this.variableName
  
  // call another constructor of the same class
  this( argumentList );
  
  // call a method of the current object
  this.methodName( argumentList )
  
  // pass the current object to a method
  objectName.methodName( this )
  
  // pass the current object to a static method
  ClassName.methodName( this )