intermediate programming

• Class


  A user-defined blueprint or prototype from which objects are created. It represents the set of properties or methods that are common to all objects of one type.
• Components of a class declaration

  • Modifiers
  • Class name
  • Superclass (if any)
  • Interfaces (if any)
  • Body
• Modifiers


  Access specifiers that determine the accessibility of a class or class member
• Access specifiers in order of restrictiveness

  • Private
  • Default
  • Protected
  • Public
• Superclass


  The class whose features are inherited
• Subclass


  The class that inherits from the superclass
• Interface

  A contract that defines a set of methods that a class must implement
• Interfaces cannot be used to create objects
• Interface methods do not have a body - the body is provided by the "implement" class
• On implementation of an interface, you must override all of its methods
• Interface methods are by default abstract and public
• Interface attributes are by default public, static, and final
• An interface cannot contain a constructor
• Why and when to use interfaces

  To achieve security - hide certain details and only show the important details of an object
• Method


  A collection of statements that perform some specific task and return the result to the caller
• Components of a method declaration

  • Modifier
  • Return type
  • Method name
  • Parameter list
  • Exception list
  • Method body
• Modifiers


  Define the method's access type
• Access specifiers for methods

  • public
  • protected
  • private
  • default
• Naming conventions for methods

  A single word that is a verb in lowercase or a multi-word that begins with a verb in lowercase followed by an adjective or noun, with the first letter of each subsequent word capitalized
• Calling a method


  1. Method completes all statements

  2. Method reaches a return statement

  3. Method throws an exception
• Method parameters


  Values passed to a method that can be used as local variables
• Arguments

  Values passed to a method when it is called
• Constructor

  A special method used to initialize objects, called when an object is created
• Constructors do not have a return type
• The constructor's name must be the same as the class name
• Constructors are not considered members of a class
• A constructor is called automatically when a new instance of an object is created
• Inside a block, variables are local to that block only.
• Enum type

  A special data type that enables for a variable to be a set of predefined constants
• Common examples of enum types

  • Compass directions (values of NORTH, SOUTH, EAST, and WEST)
  • Days of the week
• Defining an enum type in Java


  1. Use the enum keyword

  2. Separate constants with a comma

  3. Constants should be in uppercase letters
• Enum

  A data type consisting of a set of named values called elements, members, enumeral, or enumerators of the type
• BitSet


  A Java class that creates an array of boolean values, allowing non-negative integers as an index. It's easy to create and manipulate bit sets, representing a set of boolean flags, and provides detailed API usage examples.
• BitSet class


  Creates an array of bits represented by boolean values, with a flexible size that can grow to accommodate additional bits. Its index can be non-negative integers.
• BitSet


  • It is easy to create and manipulate, representing a set of boolean flags
• BitSet class constructors

  • BitSet()
  • BitSet(int no_Of_Bits)
• BitSet


  A boolean variable with a default value of false, representing 0 (off)
• Using BitSet

  1. Set bit positions to 1 (on) using the set method's zero-based index

  2. Clear the BitSet to set the bit values to false

  3. Access a specific value using the get method with an integer argument as an index
• BitSet class constructors

  • BitSet()
  • BitSet(int size)
• BitSet class methods

  • and(BitSet bitSet)
  • andNot(BitSet bitSet)
  • cardinality()
  • clear()
  • clear(int index)
  • clear(int startIndex, int endIndex)
  • clone()
  • equals(Object bitSet)
  • flip(int index)
  • flip(int startIndex, int endIndex)