Introduction to Computer Programming

1
Introduction to Computer Programming

• CS 126
• Lecture 6
• Zeke Maier

2
Plan for Today

• Questions
• Administrivia
• Quiz
• Instance Variables
• Conditionals
• Assignment

3
Questions
4
Administrivia

• http//students.cec.wustl.edu/ejm3/
• Lab assignment due Wednesday

5
Method Example Code

• http//students.cec.wustl.edu/ejm3/CS126/web/code
  .htmlinstance
• Pay attention to the coding style!

6
Variables

• Def A symbol which can hold a value of a
  particular type
• ltdataTypegt ltnamegt int count

Variable Instance Variable
Defined within a method Defined within a class
Can only be accessed within its method Can be accessed anywhere in the class
Used as a temporary holder of intermediate values Used to hold values describing the class
7
Instance/Data Variables

• How do we create an instance variable?

ltdataTypegt ltnamegt int count

• Which variable is the instance variable?

class Student String name public static void
main(String args) void printName()
String fullName Mr./Ms.
name System.out.println(Name name)
8
Class Layout

• A Class is a blueprint for an object
• It models something
• Class consists of
• Instance/Data Variables
• Describe
• Methods
• Perform Actions

9
Instance Example Code

• http//students.cec.wustl.edu/ejm3/CS126/web/code
  .htmlinstance

10
Conditional Statements

• Allows us to change the behavior of the program
  based on certain conditions
• Example absolute value

If (condition) //Statements to execute if the
condition is true
else //Statements to execute if the condition
is false
11
Assignment

• Lab 1 due Wednesday in Lab
• Readings
• Wednesday
• AD Chapter 4 4.1 - 4.7
• KG Notes