Creating Your Own Class

1
Creating Your Own Class

• Chapter 3 Section 2

2
Identifiers

• Identifier is a string of characters that names a
  class
• Class names are called identifiers
• Identifiers also used to name
• Methods
• Fields

3
Camel Case Notation

• Java is case sensitive
• Camel case notation used to name many identifiers
• Example of Camel Case Notation
• myVariableName

4
Class Fields

• Class fields-
• contain data that refer to the state of the
  object
• Are constituent parts of the class
• May also be called member variables or class
  variables
• Field names should be self explanatory

5
Type

• Class field has a type
• Type can be
• intrinsic (built in)
• User defined
• User defined must be declared

6
Example of a Type

• class Student
• intAge
• Keyword int declares the member variable age
  There are eight intrinsic types in Java

7
Java Library

• The Java library is a collection of classes
• Can help you create member variables
• Example
• class Student
• intAge
• string Name

8
String

• String is a class defined in the Java Library
• Used to hold a string of characters
• Used with quotes
• NameJoe Smith
• Assigning a value to the variable name

9
User Defined Types

• User defined types is a class the programmer
  defines
• Example
• class Tutor
• String name // name of the tutor
• Student pupil //the student being tutored

10
Keeping Data Private

• Declare the member variable with the keyword
  private
• class Dog
• private int age
• private int weight
• private String name
• Keyword private means members are visible only to
  Methods found in class Dog

11
Retrieve Data

• To retrieve data on age
• Use
• get.Age() method
• Reveals age of dog without telling client class
  how age is stored
• Private and Public are both called access
  modifiers
• Remember
• Private means data is only visible to class in
  which it was declared
• Public is available to all classes in application