Classes: user-defined types

Organizing method with a class A class is used to organize methods * Methods that compute Mathematical functions * The Scanner class

Organizing information with a class A class can also be used to organize information It defines a group of related information that belong to the same entity

Instance Variables (1) Java has 4 different kinds of variables 1. Local variables 2. Parameter variables

Instance Variables (2) 3. Class variables

Instance Variables (3) 4. Instance variables are defined inside some class are defined outside every method of that class. are defined without using the keyword static

Creating an object in Java (1) 1.Define a variable to store the location of the object. 1.Create the object

Creating an object in Java (1)

Creating an object in Java (2)

Accessing the information stored inside an object (1)

Accessing the information stored inside an object (2)

Accessibility rule for instance variables The accessibility of instance variables are controlled by access modifiers public = can be accessed in a method inside any class private = can be accessed in a method inside the same class

Lifetime of Instance variables (1)

Lifetime of Instance variables (2) These instance variables will cease to exist after the garbage collection procedure has completed execution

Methods using a object variable as parameter (1) A class in Java is equivalent to a data type

Methods using a object variable as parameter (2) Variable x and variable stu1 will access the same memory locations

Changing the values of a variable inside an object