Test 2 Review Sheet

General

• Know all the keywords covered so far in the course
• Know how to properly declare the 'main' method used to invoke a class

Classes and Objects (chapter 8)

• Objects and classes and the relationship between them
• Constructors: what they are and how to build them
• The modifiers public and private
• The static modifier, and the difference between static variables and methods vs. instance variables and methods, as well as which variables can be accessed from which methods
• Understand how to declare an object reference variable and then create the object with new, along with how to invoke the chosen constructor
• Understand how objects are passed in and out of methods
• Class scope vs. local scope (like in a method)
• The keyword this
• Arrays of objects (array of reference variables, each can attach to an object

Strings (chapter 11)

• Know the common String methods: length(), concat(), equals(), compareTo(), charAt(), substring(), trim(), toLowerCase(), toUpperCase(), replace()
• Know the common StringBuffer methods: construction from a String, append(), insert(), delete(), length(), charAt(), substring()
• Understand that a String is immutable. A StringBuffer is mutable.
• Know what the StringTokenizer class is for. Be able to interpret given code involving String tokenization. (constructor, countTokens(), nextToken())
• Understand how to process command line arguments

Inheritance and Polymorphism (chapters 9 and 10)

• Superclasses and subclasses, and deriving a class with the keyword extends
• The use of super to invoke parent constructors and methods
• Understand overriding methods in derived classes
• Every class derived somehow from class Object. Understand the 3 special methods inherited from Object by every class:
  • equals()
  • toString()
  • clone()
• Understand the modifiers protected and final, and what they do when applied to class data and methods
• Abstract classes and their relationship with abstract methods
• Understand polymorphism and dynamic binding
  • How base class variables can be attached to derived class objects
  • How base class methods can be overridden in derived classes
  • How dynamic binding allows method calls (through base class variables) to still invoke child versions of overridden methods
  • When casting is necessary between parent and child, and when it is not
• Understand interfaces, how to declare one and how to extend one
• Know how a class declares that it will implement an interface
• Understand relationship of data and methods with interfaces
• Understand the basic interfaces discussed in examples (Comparable and Clonable)
• Understand the concept of an inner class, along with their relationship with enclosing class.
• Know what an inner class '.class' file looks like

Exception Handling (chapter 15)

• Understand Exceptions, understand differences between checked exceptions, unchecked exceptions, and errors
• Understand try, catch, finally blocks and relationship between them
• Understand the throws and throw keywords and when to use both
• Custom exception types can be built, derived from Exception or one of its derived classes

Applets, GUI, basic Event Handling

• Understand that applets are extended from Applet or JApplet
• Understand the special methods used by applets, and when they are invoked. These are: init, start, paint, stop, and destroy
• Know how to embed an applet in a web page, whether it's a single .class file or in a jar archive.
• Understand the usage of the ActionListener interface to handle basic actions. The ActionListener interface contains the one abstract method:
  void actionPerformed(ActionEvent a)
• Be able to read and understand the Applet and GUI examples from Deitel chapters 3 - 8