Exam 1 Topics
CS141: Introduction to Programming, Fall 2017

General Comments and Recommendations

The exam will cover Chapters 1-5 of the text.
The exam will be 1 hour long. It will be closed book. Electronic devices, of any kind, will not be allowed.
It is strongly recommended that students:
- Re-read the text.
- Do the self-check exercises in each chapter.
- Review the reading quizzes.
- Review the lab assignments.
Practice Problems which could appear on the exam:

Chapter 1: Introduction

Vocabulary

CPU
Memory
Secondary storage
Java compiler
Java Virtual Machine
(Java) library package, e.g. see Java API
source file
byte code
class file
IDE - Integrated Development Enviroment (e.g Netbeans)
backing up

syntax
case sensitive
block of code
main method
statement
string
compile time error
run-time error
algorithm
pseudocode

Misc Topics

Java sytax for creating a class.
What is a statement?
How is a block of code specified (i.e. with braces)?
Name of java file must be same as the java class.
Printing output using System.out.println()
Programming Conventions (Style guide):
- files names begin with uppercase
- method (function) names begin with lowercase
- Blocks of code are indented, i.e. Code within braces is indented.
What are compile vs run-time errors?

Chapter 2 & 4: Fundamental Data Types

Vocabulary

Variables:
  ... variable declaration
  ... primitive data types (int, float, double, boolean, char)
  ... identifier, naming, camel case (see p. 37)
  ... reserved words
  ... variable initialization
  ... case sensitive
  ... literal, String literal
  ... scope, code block (brackets {...} )
  ... constants
  ... magic numbers

Variable Operations:
  ... variable assignment, assignment statement
  ... operator
  ... assignment statement
  ... binary arithmetic operators: +, -, *, /, %
  ... unary arithmetic operators: -, ++, --
  ... Mod function (%)
  ... integer division
  ... Math class, Math.PI, Math.random()
  ... operator precedence
  ... type conversion, cast operator

Other:
  ... stepwise refinement
  ... sytax rules vs convention
  ... statement vs expression
  ... programming style, indentation, Netbeans formatting tool
  ... comments, single line, multi-line, Javadoc

String Variables and Operations:
  ... String Class
  ... String operations
  ... escape sequence and control characters
  ... String concatenation and the + operator
  ... dot notation

Keyboard I/O, input/output:
  ... Scanner class
  ... Dialog Boxes
  ... System.out.print, System.out.println
  ... System.out.printf, format specifier
  ... console
  ... standard output/input

Misc Topics

Sample problems: Variables (pdf)
Variables: What are they, how do you create, name, and initialize them?
How many times can one declare a given variable? How many times can one set the value of a given variable?
Types: What is a data type? Why do we have them? What are examples (int,float, boolean, String, etc.)
When can we convert from one type to another? What is casting?
Java Statements: What is a statement, expression, value?
What is a "literal"?
Assignment statement: What is its syntax?
Doing Arithmetic
- Operators - binary (+, -, /, *, %) , unary (-, ++, --)
- Operator Precedence and when you must use parentheses
- The Math class for functions such as sqrt, pow, etc. -
  Learn to use the javadoc api !
- Conversion between numeric types.
Comments: What are they? Why do we have them? What is their syntax?
Common Pitfalls:
- Forgetting to declare and/or initialize a variable.
- Declaring a variable multiple times.
- Using integer division when you don't mean to.
Problem Solving techniques
- Don't jump into coding too quickly. Understand problem, try example by hand, write pseudocode.
- Stepwise refinement - break problem into a sequence of steps that lead to the full solution. Implement one step at a time, compiling (compile time errors) and testing your code (run time erros)
Strings: What is a string? Look at String API (Javadoc).
String methods (e.g. length, charAt, substring) and sytax for calling them, StringName.methodName(inputs_to_method).
String concatentation and escape sequences
Math methods (e.g. min, max, pow, sqrt)
Primitive types (int, float, etc) vs Object types (String, Scanner, etc):

Chapter 2 & 3: Classes and Objects

Vocabulary

Object-oriented programming & Class Structure
  ... Class (user defined type)
  ... Object (instance of class)
  ... primitive type vs class type
  ... Attributes, Fields, or Member variables (data)
  ... Methods (actions)

Method Structure:
  ... access specifier or modifier (e.g. public, private)
  ... method name
  ... method parameters
  ... pass by value vs pass by reference
  ... return type, return value
  ... variable scope: local vs global, shadowing

Class Structure (more detail):
  ... Constructors, default constructor
  ... Public interface
  ... Private implementation, data hiding
  ... Mutator methods (setter)
  ... Accessor methods (getter)
  ... toString method
Object Creation and Use
  ... The keyword: new
  ... Sending a message, calling a method
  ... dot notation
  ... (formal) parameter vs argument (actual parameter)
  ... parameter passing
  ... Null pointer and the Null Pointer Exceptions
  ... Self reference keyword this

Code Design and Development
  ... UML Diagram
  ... Javadoc
  ... API (Application Programmer Interface)
  ... Encapsulation, modularization
  ... stepwise refinement
  ... reusability

Testing and Debugging
  ... debugging & testing
  ... tracing code
  ... unit testing

Topics

What are classes? What are objects?
Primitives vs objects, Object references
Existing classes: Java libraries, packages, understanding the Application Programmer Interface (API)
- Creating an object using the keyword new and a constructor
- The null keyword and Null Pointer Exceptions
- Sending an object a message using the public interface. (calling a method)
Motivation of Classes and Objects: Organizing and structuring code to promote reusability, readability, and correctness
Encapsulation: Separating the public interface from the private (hidden) implementation.
Variable scope - what is it and why we have it. Local vs instance/member variables
Class vs Object Analogies: script vs actor, cookie recipe vs the cookie itself
Example: Die class
Components of a Class (also see class template):
- Data (Attributes, Fields):
  - Member (instance) variables (one for each object)
  - Class (static) variables (one for all objects)
- Actions:
  - Public interface (public methods)
    - Common for most classes:
      - Creation: Constructor
      - Access to data: Mutators and Accessors (also called getters and setters)
      - Handy Utility: toString
    - Public methods for a specific class (e.g. In the Die class, one might have a roll() method)
  - Private Implementation:
    - Data hiding: data is usually private. Use accessors & mutators instead.
    - private methods - not accesible from outside of the class.
Be able to draw what is happening in memory when variables ( primitives or classes) are created or destroyed.
Self referencing using the keyword this
What are UML Diagrams and why are the used?

Practice

Methods: Practice problems (pdf).
Classes: Practice problems (pdf).
Scope: Practice problems (pdf).
Pass by Value vs Reference example (pdf).

References: For the following code, what is printed? Draw what is happening in memory at each step.:

Rectangle rec1 = new Rectangle(5,6,10,10);
System.out.println("rec1: " + rec1);
Rectangle rec2 = rec1;
rec1.setLocation(100,150);
System.out.println("rec1: " + rec1);
System.out.println("rec2: " + rec2);
rec1 =  new Rectangle(50,60,20,20);
System.out.println("rec1: " + rec1);
System.out.println("rec2: " + rec2);

Chapter 5: Decisions

Vocabulary

Types of Decision Structures:
  ... if statement
  ... if-else statement
  ... multi-way if-else
  ... nested if-else
  ... switch statements
  ... indentation conventions
Code blocks & variable scope

Decision Structure Syntax:
  ... decision logic and flow charts
  ... condition and body
  ... boolean value, expression

Random numbers

Building Boolean Expressions:
  ... relational operator (<, >, <=, >=, ==, !=)
  ... boolean (logical) operators (!, &&, ||). Examples
  ... boolean operators precedence (See table)
  ... truth tables (p. 209)
  ... De Morgan's Laws (p. 212)

String Comparison
  ... Lexicographic ordering (of Strings)
  ... compareTo() and .equals operators

Other (optional)
  ... The Conditional Operator bool ? val1 : val2 (p. 182)
  ... Switch statement (p. 195)

Misc Topics

If-statement, if-else
- Syntax
- Code Blocks & Scope - Braces & indentation
- Boolean values and variables:
  - What is a boolean variable? (boolean, true/false)
  - Relational operators - making number comparisons with <, >, <=. >=, ==, !=
  - Be careful!! Equality of Strings. Do not use ==. Instead, use myString1.equals(myString2)
Adding Complexity: Multi-way, nested if-else
- Branch, branching, flow charts
Boolean operators &&, ||, ! Watch precedence. Write out truth tables.
- Combining with relational operators
Strings and lexicographic ordering - compareTo operator
Rules of Thumb & Common Errors:
- Avoid duplication in branches
- Dangling else problem
- Syntax for condition ( 5 < x < 7 ) is NOT allowed! Need to use boolean operators.
De Morgan's Law:
- !(A && B) same as (!A) || (!B)
- !(A || B) same as (!A) && (!B)
Less Commonly used structures:
- Conditional Operator :
  - condition ? value1 : value2;
  - Example: int bigger = (x>y) ? x : y ;
- Switch statement: switch (digit) { case a: break; ...default: ... }
  where digit can be byte, short, int, char, enumerated types (discussed in later chapter), and (recently) Strings

Exam 1 Topics CS141: Introduction to Programming, Fall 2017

General Comments and Recommendations

Chapter 1: Introduction

Chapter 2 & 4: Fundamental Data Types

Chapter 2 & 3: Classes and Objects

Chapter 5: Decisions

Exam 1 Topics
CS141: Introduction to Programming, Fall 2017