Reviewing for the Midterm Covers chapters 1 to 5, 7 to 9 Instructor: Scott Kristjanson CMPT 125/125 SFU Burnaby, Fall 2013
Things to Review 2 Review the Class Slides: • Key Things to Take Away – Do you understand these the points? • Review Slides, especially if some Key Points are unclear Make use of the Textbook • Answer Self-Review Questions at back of each chapter • Select Exercises and Programming Projects to practice Review Quiz and Assignments • Do you understand how to answer Assignment 3 Written Questions? • Review Quiz #1 and Assignment #2 questions, then see the solutions Get some Coding Practice! • Sign up on CodingBat.com and work through the problems there Scott Kristjanson – CMPT 125/126 – SFU Wk07.5 Slide 2 Slides based on Java Foundations 3rd Edition, Lewis/DePasquale/Chase
Review the Class Slides 3 Week 01 • wk01.3 – Background Info, Introduction Week 02 • wk02.1 – Introduction to Java • wk02.3 – Intro to Objects and String and Scanner Objects • wk02.5 – Packages Enums and Wrappers Week 03 • wk03.1 – Boolean Expressions, Conditionals, Definite Loops Week 04 • wk04.1 – Structured Analysis and Data Flow Diagrams • wk04.3 – Review Week 05 • wk05.1 – Writing Classes • wk05.5 – Quiz 1 Solutions Week 06 • wk06.1 – Testing • wk06.3 – Arrays • wk06.5 – Inheritance Week 07 • wk07.3 – Polymorphism Scott Kristjanson – CMPT 125/126 – SFU Wk07.5 Slide 3 Slides based on Java Foundations 3rd Edition, Lewis/DePasquale/Chase
Wk02.1 Slides: Introduction to Java Chapters 1 and 2 The Java Language – Section 1.1 Data & Expressions – Sections 2.1 – 2.5 Instructor: Scott Kristjanson CMPT 125/125 SFU Burnaby, Fall 2013
Ch 1&2 - Key Things to take away: 5 • The print and println methods are two services provided by the System.out object • In Java, the + operator is used both for addition and for string concatenation • An escape character can be used to represent a character that would otherwise cause a compile error • A variable is a name for a memory location used to hold a value of a particular data type • Accessing data leaves them intact in memory, but an assignment statement overwrites old data • One cannot assign a value of one type to a variable of an incompatible type • Constants hold a particular value for the duration of their existence • Java has two types of numeric values: integer and floating point. There are four integer data types and two floating point data types • Java using 16-bit Unicode character set to represent character data • Expressions are combinations of operators and operands used to perform a calculation • The type of result produced by arithmetic division depends on the types of the operands • Java follows a well-defined set of precedence rules that governs the order in which operators will be evaluated in an expression • Narrowing conversions should be avoided because they can lose information Scott Kristjanson – CMPT 125/126 – SFU Wk07.5 Slide 5 Slides based on Java Foundations 3rd Edition, Lewis/DePasquale/Chase
Wk02.3 Slides: Using Classes and Objects Chapters 3 Creating Objects – Section 3.1 The String Class – Section 3.2 The Scanner Class – Section 2.6 Instructor: Scott Kristjanson CMPT 125/125 SFU Burnaby, Fall 2013
Key Things to take away: 7 • Object declarations create place holders which point to an object in memory • The new operator instantiates a new instance of the class • Strings are immutable – changing a string creates a new instance • A variable holds either a primitive type or a reference to an object • Assigning variables of primitive types copies the value • Assigning variables of class types copies a reference to the object • The String class provides useful methods for working with strings length • concat • substring • toUpperCase • • Etc • The System.in object represents the standard input stream • The Scanner Class provides methods for reading input values Scott Kristjanson – CMPT 125/126 – SFU Wk07.5 Slide 7 Slides based on Java Foundations 3rd Edition, Lewis/DePasquale/Chase
Wk02.5 Slides: Using Classes and Objects Chapters 3 Section 3.3 Packages Section 3.4 Random Class Section 3.5 Math Class Section 3.7 Enumerated Types Instructor: Scott Kristjanson CMPT 125/125 SFU Burnaby, Fall 2013
Key Things to take away: 9 • The Java API contains standard set of class definitions • Class definitions can be reused by importing packages • Packages exist for creating random numbers, math, and formatting • You can create your own set of libraries as a package • Java provides wrapper classes for primitive data types so they can be used just like any other object Scott Kristjanson – CMPT 125/126 – SFU Wk07.5 Slide 9 Slides based on Java Foundations 3rd Edition, Lewis/DePasquale/Chase
Wk03.1 Slides Conditionals and Loops Chapter 4 Instructor: Scott Kristjanson CMPT 125/125 SFU Burnaby, Fall 2013
Key Things to take away: 11 • Flow of Control determines which statements get executed • Expressions can form complex conditions using logical operators • AND and OR evaluation are short-circuited in Java • Selection statements chose different execution paths based on conditions • If <condition> then <statement>; • If <condition> then <statement1> else <statement2>; • Switch <integer value> {Case 1, Case 2, … Case N} • Java supports two styles of Indefinite Loops: • While <condition> <statement>; • Do <statement> while <condition>; • Java suports two styles of definite Loops: • for ( initialization ; condition ; increment ) <statement>; • For-each using Iterators Scott Kristjanson – CMPT 125/126 – SFU Wk07.5 Slide 11 Slides based on Java Foundations 3rd Edition, Lewis/DePasquale/Chase
Wk04.1 - Wk05.5 Slides: Writing Classes Chapter 5 Instructor: Scott Kristjanson CMPT 125/125 SFU Burnaby, Fall 2013
Key Things to take away: 13 Class and Method Design • Data Flow Diagrams help get a design started • Problem Specification: Nouns become Classes, Verbs become Methods • Decompose methods that get too complex Class and Method Coding • Methods and Variables have Scope – where they can be seen • Public Scope allows access by users of the Class • Private Scope used to encapsulate data and internal helper methods • Invoking a method copies the actual parameters into the formal parameters • Object Parameters contain references to the actual object and can be modified Testing • Methodical Testing is important step, every program has bugs • Testing can be black box (functional) or white box (implementation) • Four types of tests: Unit, Integration, System, Regression • Println’s and the Eclipse Debugger are essential tools for debugging Scott Kristjanson – CMPT 125/126 – SFU Wk07.5 Slide 13 Slides based on Java Foundations 3rd Edition, Lewis/DePasquale/Chase
Wk04.3 Slides: Review Chapters 1 to 4 Instructor: Scott Kristjanson CMPT 125/125 SFU Burnaby, Fall 2013
Key Things to take away: 15 • Flow of Control determines which statements get executed • Expressions can form complex conditions using logical operators • AND and OR evaluation are short-circuited in Java • Selection statements chose different execution paths based on conditions • If <condition> then <statement>; • If <condition> then <statement1> else <statement2>; • Switch <integer value> {Case 1, Case 2, … Case N} • Java supports two styles of Indefinite Loops: • While <condition> <statement>; • Do <statement> while <condition>; • Java suports two styles of definite Loops: • for ( initialization ; condition ; increment ) <statement>; • For-each using Iterators Scott Kristjanson – CMPT 125/126 – SFU Wk07.5 Slide 15 Slides based on Java Foundations 3rd Edition, Lewis/DePasquale/Chase
Wk05.5 Slides: Quiz #1 Solutions Instructor: Scott Kristjanson CMPT 125/125 SFU Burnaby, Fall 2013
Question 3 17 !A && (B || C) Work out the logic one step at a time: Validate using a Truth Table: • True when A is false => !A A B C !A B||C !A && (B || C) • Either B or C are true => B || C F F F T F F • AND => both the above must be true => !A && B || C • F F T T T T But remember to check precedence! F T F T T T => !A && B || C is evaluated as • =>( !A && B)|| C • F T T T T T That’s not right! T F F F F F Need to add parenthesis => !A && (B || C) T F T F T F • T T F F T F T T T F T F Scott Kristjanson – CMPT 125/126 – SFU Wk07.5 Slide 17 Slides based on Java Foundations 3rd Edition, Lewis/DePasquale/Chase
Question 4 18 for (int i=1; i <= 9; i += 2) { System.out.println(i); } For full marks, • Do not go through the loop 9 times, execute the loop 5 times • Realize that you can increment counter by 2 within the loop, not by 1 twice • Declare the loop variable within the for loop If you do not remember HOW to write a Java for loop… • Use Appendix J – it was attached at the back! Scott Kristjanson – CMPT 125/126 – SFU Wk07.5 Slide 18 Slides based on Java Foundations 3rd Edition, Lewis/DePasquale/Chase
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