1. Course Information

What We Will Cover

Exercise 1.1

Instructions

Use the next 15 minutes to complete the following.

  1. Join a group of 3-4 people and prepare an answer to one of the following questions.
  2. Select one member from your group as a representative to describe your answer to the class.
  3. Start a text file named exercise1.txt.
  4. Prepare the exercise header as described in the HowTo on submitting exercises
  5. Label this exercise: Exercise 1.1
  6. Submit all exercises for this lesson in one file unless instructed otherwise
  7. Arrange for each student in your group to get a copy of your group's question and answer.

Exercise Questions

  1. What "burning questions" do you have about the course outline?
  2. What can you hope to learn by the time you complete this course?
  3. How do you plan to balance the work required by this course with the other activities in your life?

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1.2: Succeeding in This Course

Objectives

At the end of the lesson the student will be able to:

  • Describe how to study effectively for this course
  • Use computers in the CTC for homework
  • Install software used in this course at home

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1.2.1: Elements of Success

  • Programming requires you to know many facts and procedures
  • Also, you must learn how to solve problems
  • To help you master the materials, I provide you with exercises and assignments in addition to lectures
  • To succeed in this course, you need to make use of this material

Attend Class

  • You need to attend class and pay attention
  • When asked questions, you need to respond
  • When you cannot attend class for some reason, you need to catch up before the next class meeting

Complete In-Class Exercises During Class

  • In-class exercises are problems you are given class-time to complete
  • You should complete these problems during the allotted time in class
    • However, you have about one-week to complete them after class
    • See WebCT for the exact date and time
  • You can discuss them with partners or the instructor
    • Much easier to solve problems in the classroom than at home
  • You should submit the exercises to WebCT before you leave the classroom
    • Ensures that something is turned in on time
    • You can always unsubmit them if you want to make changes during the week
  • Graded on a best-effort basis
    • You get full credit for just attempting to complete the exercise

Complete On-line Exercises On-time

  • Online exercises (CodeLab) are due about a week after we discuss the topics
  • CodeLab gives you a series of graduated exercises with "instant" feedback
  • I suggest that you complete the on-line exercises before the homework assignment

Complete Homework Assignments

  • Homework assignments have you apply and explore lecture concepts
  • Homework assignments can include reading, quizzes and writing code
  • If you get confused about or stuck on an assignment:
  • Submit homework to WebCT at least the day before it is due
    • Even if you are not done, turn it in
    • You get some credit for what you did complete
    • Make sure to state an accurate status in the README.txt file
  • Note that homework deadlines are real -- late homework is not accepted
  • Instead, most homework has extra credit possibilities

Study for Exams

  • Most students do not have perfect memories
  • You need to refresh your memory about programming details before an exam
  • Plan on spending time studying for exams
  • I will discuss study techniques before the exams

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1.2.2: Time Estimates

  • Students often ask how much times is needed for a course
  • Estimated average course time per week:
    • 1 hour reading the lecture notes and textbook before class
    • 4 hours in the classroom
    • 8 hours for on-line exercises and homework assignments (excluding extra credit)
  • I collect time estimates from students

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1.2.3: Using the CTC for Homework Assignments

  • First you will need a login and password
  • You can use either Linux, Macintosh or Windows computers for your assignments
  • For more information, follow the link to the CTC homepage

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1.2.4: Can I Run This On My Own Computer?

  • All the technology we use runs on most any computer
  • Instructions on How To Install Java available from the HowTo's page
  • Also has instructions for installing jEdit and TextPad

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1.2.5: Summary

  • Elements of success in this course:
    1. Attend class and actively participate
    2. Submit the in-class exercises before you leave
    3. Complete on-line exercises on-time
    4. Do your homework assignments and turn them in on time
    5. Prepare for and attend exams
  • You can complete homework assignments in the CTC
  • Also, you can install the necessary software at home or work

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Exercise 1.2

With no more than a single partner, take 5 minutes to complete the following.

  1. Label this exercise: Exercise 1.2
  2. Submit all exercises for this lesson in one file unless instructed otherwise
  3. Complete the following and record the answers to any questions in exercise1.txt.

Specifications

  1. List the elements of success for this course
  2. What is the average time you can expect to spend outside the classroom on this course?
  3. Where do you plan to work on your programming assignments?

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1.3: Introduction to Java

Objectives

At the end of the lesson the student will be able to:

  • Describe the programming process
  • Name and describe three types of programs you can create with Java
  • Describe how Java compares with C++

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1.3.1: What Programming is About

  • Programming is about solving problems using a computer program
  • As such, programming requires a number of steps
  • Note that the first two steps do not require a computer

Programming Process

  1. First step is to define the problem
    • You need to describe the nature or basic properties of a problem
    • In addition, you need to describe your goal
    • Understanding a problem to this degree prepares you to solve it
  2. Next step is to define an algorithm
    • Set of steps for performing a task
    • Often has steps that repeat or require decisions
    • Can be expressed using psuedocode
  3. Then you actually write the program using a programming language
    • The language we use for this course is called Java
  4. As you write the program code, you translate human-readable source code into a language understood by the computer
    • Usually with a program called a compiler
    • Discuss compiling later today
  5. After code compiles, you test it to make sure it:
    • Does what it is supposed to do
    • Does not do what it is not supposed to do
    • Does what it used to do
  6. When it works well, you document and deliver the program

More information

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1.3.2: Introducing Java

  • Java is a programming language
  • A programming language allows a programmer to describe a computation
  • Java is a high-level language
  • High-level programming languages are easier to use than low-level languages

History of Java

  • 1990 - "Green" project started at Sun
    • Java originally called Oak
    • Developed for digitally controlled consumer devices and computers
  • 1991 - Java created by James Gosling, Sun Microsystems, Inc.
  • 1992 - "Green" project finished
  • 1992 - 1994 - Tried to turn "Green" technology into products
    • Failed
    • But then the Internet happened...
  • 1996 - Official launch of JDK 1.0
    • Primary focus was Applets
  • 1997 - Sun releases JDK 1.1
  • 1998 - Sun releases SDK 1.2
    • Now called the Java Platform
  • 2000 - Sun releases SDK 1.3
  • 2002 - Sun releases SDK 1.4
  • 2004 - Sun releases SDK 1.5
  • Today a general-purpose programming language used extensively

More information

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1.3.3: Applets, Applications and Servlets

  • Java has many uses including:

Applets

  • Applet: a Java program that runs in a browser
  • Original impetus for Java was applets
  • Two famous applets captured the attention of Netscape
  • Applets can show 2D and 3D images, play sound, and show video

Desktop Applications

  • Applications are programs that perform specific functions for users
    • Word processors
    • Spreadsheets
    • Drawing programs
    • Games
  • One example: jEdit
    • Text editor written in Java
  • Most modern applications use a Graphical User Interface (GUI)
  • Java provides a complete set of APIs for programming GUIs
  • Will use GUIs throughout the course

Mobile Applications

  • Java installed on many cell phones provides new opportunities for:
    • Mobile games
    • Productivity applications like expense trackers
    • Messaging applications like auction tracking
    • Information applications like news and stock info
  • A lot of development work going on in this area

Web-Based Applications

  • Web applications are programs that perform specific tasks for the Web
  • Java is the dominant programming language for developing these applications
  • Java provides special server-side application known as a servlet
  • Examples of Web-base applications:
  • May Web-based games are written in Java

More Information

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1.3.4: Java Compared to C++

  • Syntax intentionally similar to C++
    • Easy for C++ programmers to move to Java
  • Has several important advances over C++
  • All programs are encapsulated in classes
    • "Pure" object-oriented language
    • OOP improves programmer productivity (>2X)
  • Automatic memory management ("garbage" collection)
    • Improves memory management and reliability
  • More intelligent use of pointers (references)
    • No pointer arithmetic
    • Simpler model
    • Less error prone and more reliable
  • Build-in bounds checking of arrays
    • Helps prevent buffer overflow
    • Buffer overflows are one of the leading causes of computer vulnerabilities
  • Built-in support for multithreading
  • Large class-libraries
    • Known as APIs (Application Programming Interfaces)
  • Runs without recompiling on many operating systems and hardware platforms
    • Uses a virtual machine
  • Fastest Java runs slower than fastest C++
    • Originally about 10x slower, now about 2x with "Hotspot" compiler
    • Compilers exist to translate directly to native machine code (GCJ)
    • Lose portability when compiled
    • Note that Java is usually faster than MS Visual C++
    • Moore's law makes this issue less important every day

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1.3.5: Summary

  • Java used to develop many types of programs including:
    • Applications: programs that perform specific functions for users
    • Applets: a Java program that runs in a browser
    • Servlet: server-side application
  • Java often compared to C++
    • Similar syntax
    • Bounds-checking of arrays
    • Automatic memory management (not present in C++)
    • Better model for using pointers (references)
    • Built-in support for multithreading
    • Runs slower than C++

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Exercise 1.3

  1. Label this exercise: Exercise 1.3
  2. Submit all exercises for this lesson in one file unless instructed otherwise
  3. Complete the following and record the answers to any questions in exercise1.txt.

Specifications

  1. What are three types of programs you can create with Java?/li>
  2. How does Java compare with C++?
  3. How can Java performance be improved so that it is as fast as C++?

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1.4: Editing, Compiling and Running Java Programs

Objectives

At the end of the lesson the student will be able to:

  • Explain how a virtual machine helps Java achieve platform independence
  • Compile and run Java programs, given the source code
  • Display program output to a console

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1.4.1: Using the Windows Command Line

  • Windows provides a command-line interface to the Operating System
    • Sometimes known as a Console
  • The command line provides direct access to the File System and allows you to run ALL types of programs
  • To use the command line, you type commands at a command prompt
    • C:\>dir
  • After typing a command, you press the Enter key

Starting a Console Session

  1. From the Start menu, Select Run...
  2. In the text box, type:
    • cmd for Windows NT/2000/XP
    • command for Windows 95/98/ME

Ending a Console Session

  • At the command line, type exit
    • C:\>exit

Getting Help

  • Once you have a command line, you can get a list of commands by typing: help
    • C:\>help
  • To get help for a specific command, you type help followed by the command
  • For example, to find out more about using the cd command:
    • C:\>help cd

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1.4.2: Navigating Directories and Viewing Files

  • When a console session starts, you may not be in the directory you want
  • You can verify the current directory location by looking at the command prompt
    • C:\j2sdk1.5.0>
  • You can list the files in the current directory using dir
    • C:\>dir
  • To change to a lower subdirectory level: cd directoryName
    • C:\>cd "Documents and Settings"
  • Change up one directory level: cd .. (change directory)
    • C:\>cd ..
  • Change to the root of the file system: cd \
    • C:\>cd \
  • Change to any location in the file system: cd path
    • C:\>cd \Documents and Settings\YourLogin\Desktop
  • You can view a file using more followed by the name of the file
    • C:\>more exercise1.txt
  • An easier way to view files is to use either Notepad or TextPad
  • For exampe, to view a file using Notepad:
    • C:\>notepad exercise1.txt

More Information

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1.4.3: How Java Compiles and Interprets Code

  • Developing Java code consists of three steps
    1. Writing the source code
    2. Compiling the source code to bytecode
    3. Executing (running) the program
  • This process is repeated many times during development

Three steps to creating a Java program:

  1. Editing
    • Write a program's source code using any text editor
    • Save the source code on file system or network
    • Source code files have a .java suffix
  2. Compilation
    • Use a compiler to translate the source code to bytecodes
    • Files with translated bytecodes have .class suffix
  3. Execution
    • Use the java interpreter program to run the bytecodes
    • Class Loader: moves bytecodes from file system or network into memory
    • Bytecode Verifier: tests bytecodes to establish safety and security
    • Interpreter (JVM): translates bytecodes into machine language

Java Virtual Machine (JVM) makes "write once, run anywhere" possible

More Information

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1.4.4: Writing, Editing and Saving Source Code

  • You can use almost any text editor to write and save Java source code
    • Windows: jEdit, Notepad, WordPad, TextPad, ...
    • Linux/UNIX: jEdit, VIM, gedit, pico, ...
    • Mac: jEdit, SimpleCap, ...
  • Make sure you save the file using the four-letter extension: java

About Using IDEs

  • There are many Integrated Development Environments (IDEs) available for Java
    • Typically provide visual tools for designing forms and debugging code
  • I do not recommend using an IDE while learning Java
    • An IDE will generate code for you, which does not help you learn
    • IDEs are complex tools that themselves are difficult to learn
    • Learning the tool can distract you from your goal of learning Java
  • I do recommend using IDEs once you have a good understanding of Java
    • Easier to develop user interfaces
    • Improves programmer productivity
  • Any program you submit must run from the command line

Sample Program: Hello World

  • Here is an example program you can save as a source code file
    • public class HelloWorld {
     public static void main(String[] args) {
        System.out.println("Hello, world!");
    }
}
  • Copy this into a text editor and then save it
  • The next step is to compile and run the program

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1.4.5: Compiling and Running Programs

Compiling Source Code

  • Open a window with a command prompt
  • Change the directory (cd) to where program source code is stored
  • Type: javac HelloWorld.java
  • If no errors, the compiler creates HelloWorld.class
  • You can verify the HelloWorld.class file exists using the dir command

Running a Program

  • Type: java HelloWorld
    • Interpreter loads .class file for HelloWorld
    • Note that .class suffix is not typed
  • Interpreter calls the main method by default

Using Text Editors

  • Many text editors have provision for compiling within the editor
  • TextPad: Tools menu
  • jEdit: Press the java and javac folder tabs
  • Programming style: Lines no longer than 80 characters
  • Programming style: Do not use tabs

More Information

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1.4.6: Summary

  • Java programs require three steps:
    1. Create source code with an editor (or IDE)
    2. Compile to bytecode using a compiler (javac FileName.java)
    3. Execute using a JVM (java FileName)
  • You can use most any text editor for writing and editing source code
  • Many text editors provide features to make it easier to compile and run programs
  • Once you have mastered the basics of Java, you should use an IDE
  • While you are learning, it is better to use a text editor

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Exercise 1.4

  1. Label this exercise: Exercise 1.4
  2. Complete Exercise 1-2 on page 33 of the textbook. Include the NotepadTest.java and NotepadTest.class files when submitting the exercises for this week.
  3. Record answers to the following questions in your exercise1.txt file.

Questions

  1. How does the Java Virtual Machine help Java achieve platform independence?
  2. Assume that the code you want to compile from the command line is in the directory: C:\code. What command to you type at the command line to move the console window to this directory?

Note: do not forget to turn in your exercises following the instructions on How To Submit In-Class Exercises.

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Wrap Up

Due Next:
A1: Information Please! (9/8/04)
Exercise 1 and CodeLab Lesson 1 (9/8/04)

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Last Updated: July 07 2004 @18:16:36