Blakes 21 Days Experience - Original Day 1 and Appendix A

Day 1, Getting Started with Java

Appendix A - First Try

Appendix A - Second Try's a Charm

Reserve for the continuation of Chapter One

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Paths to different files

Creating the Second Java program from this book

    Only do this if you didn't create the last program.
    page 019 It will be useful to have a project to hold the classes you create in this book
  1. Choose the menu command File, New Project. The New Project dialog appears.
  2. In the Categories pane, choose Java.
  3. In the Projects pane, choose Java Application and click Next. The New Java Application dialog opens.
  4. In the Project Name text field, enter the name of the project (I used Java21). The Project Folder field is updated as you type the name. Make a note of this folder, it's where your Java programs can be found on your computer.
  5. Deselect the check box Create Main Class.
  6. Click Finish.
    page 020 To begin your first class, run NetBeans and start a new prgram.
  1. Choose the menu command File, New File. The New File dialog appears.
  2. In the Categories pane, choose Java.
  3. In the File Types pane, choose Empty Java File and click Next. The Empty Java File dialog opens.
  4. In the Class Name text field, enter MarsRobot. The file you're creating is shown in the Created File field, which can't be edited. This file has the name MarsRobot.java.
  5. Click Finish.
  1. class MarsRobot {
  2.     String status;
  3.     int speed;
  4.     float temperature;
  5.     
  6.     void checkTemperature() {
  7.         if (Temperature < -80) {
  8.             status = "return home";
  9.             speed = 5;
  10.         }
  11.     }
  12.     
  13.     void showAttributes() {
  14.         System.out.println("Status: " + status);
  15.         System.out.println("Speed: " + speed);
  16.         System.out.println("Temperature: " + temperature);
  17.     }
  18. }
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Screenshots for the instructions above

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"File" from the menu bar, "New File" from the submenu.

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The "New File" dialog box

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The "New File" dialog box

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The "New Empty Java File" dialog box

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The "New Empty Java File" dialog box

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The MarsRobot.java tab is created & displayed

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after typing in the code, note line 7 "Temparature" should not be capitalized

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Getting ready to save

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The "Save All" button is now greyed out

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Fixing my Typo

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About the MarsRobot Class

About the Three Instance Variables

Page 21 - The First Instance Method ...

Page 22 - The Second Instance Method ...

Time to save the file if you haven't done so.

Why You Cannot Run This Program

Two ways to put MarsRobot to use

The first option is chosen for this exercise

To begin the second class follow these steps in NetBeans.

  1. Choose File, New File from the menu. The New File dialog opens.
  2. In the Category pane choose Java
  3. In the File Types pane, choose Empty Java File and click Next. The Empty Java File dialog opens
  4. In the Class Name text field, enter MarsApplication. The file you're creating is shown in the Created File field and has the name MarsApplication.java.
  5. Click Finish.

Listing 1.2

class MarsApplication {
    public static void main(String[] arguments) {
        MarsRobot spirit = new MarsRobot();
        spirit.status = "exploring";
        spirit.speed = 2;
        spirit.temperature = -60;

        spirit.showAttributes();
        System.out.println("Increasing speed to 3.");
        spirit.speed = 3;
        spirit.showAttributes();
        System.out.println("Changing temperature to -90.");
        spirit.temperature = -90;
        spirit.showAttributes();
        System.out.println("Changing the temperature.");
        spirit.checkTemperature();
        spirit.showAttributes();
    }
}

Run the Program

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When I run the program I get the wrong output.

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Now I have the correct output.

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Displaying the Java code for the MarsApplication: Program or Class

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About the Java code for the MarsApplication: Program or Class

Organizing Classes and Class Behavior

Inheritance - is a mechanism that enables one class to inhert the behavior and attributes of another class

Interfaces - is a collection of methods that indicate a class has some behavior in addition to what it inherits from its superclasses

Packages - enable groups of classes to be referrenced more easily in other classes

Summary

Q&A

Quiz

Questions

  1. What is another word for class?
    1. Object
    2. Template
    3. Instance
  2. When you create a subclass, what must you define about that class?
    1. Nothing. Everything is defined already.
    2. Things that are different from its superclass
    3. Everything about the class
  3. What does an instance method of a class represent?
    1. The attributes of that class
    2. The behavior of that class
    3. The behavior of an object created from that class
  4. reserve

Answers

  1. B. A class is an abstract template used to create objects that are similar to each other.
  2. B. You define how the subclass is different from its superclass.
  3. C. Instance methods refer to a specific object's behavior. Class methods refer to the behavior of all objects belonging to that class.

Certification Practice

  1. All objects created from the same class must be identical.
  2. All objects created from the same class can have different attributes than each other.
  3. An object inherits attributes and behavior from the class used to create it.
  4. A class inherits attributes and behavior from its subclass.

Exercises

  1. In the main() method of the MarsRobot class, create a second MarsRobot robot named opportunity, set up its instance variables, and display them.
  2. Create an inheritance hierarchy for the pieces of a chess set.

End of Day One

Download JDK 8 - Not Successful

Safari

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Firefox

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10a

Questions that I answered for "Java SE Development Kit 8 Downloads" using the Firefox browser on my Apple

Download NetBeans - Not Successful

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Another Failure

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Java SE Development Kit 8 Downloads (8u112 for Mac OS X) - Success

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Downloaded NetBeans IDE 8.0.2 using Java SE - Success

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Using NetBeans

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Splash Screen

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first view of NetBeans

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New Project window

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Name and Location

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After changing "Project Name"

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After changing "Create Main Class"

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view code for first time

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after inserting new line of code

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Compile Code

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Run File

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Output Pane first appears

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Fixing Errors

the Before shot

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the After shot

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The yellow Tool Tip

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replacing the semi-colon gets rid of the error warnings

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after "Saving All" button pressed and "Run File" selected

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Opening Sparticus.java to see the code

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Sparticus.java displayed in the Projects pane, Start Page tab has focus

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Sparticus.java displayed with it's submenu

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Sparticus.java code is revealed

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Creating a NetBeans alias and placing it into the Dock

Expanding and Shrinking a pane

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Expanding and Shrinking a pane

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Expanding and Shrinking a pane

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Install the Java SE Development Kit 8u112 for Windows x64 on my Laptop

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Installing NetBeans on the Laptop

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Installation Folders

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Setup Complete

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First time viewing Netbeans on my Laptop

NetBeans seen from the Start Button

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NetBeans seen from the Desktop

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The Splash screen

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The New Project button

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After clicking the Next button

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Changing Project Name

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Changing Name to Create Main Class

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First time seeing code

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Adding the line of code

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Compiling the Java Code

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Run File

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After updating OS X, to run Dreamwaeaver CS6, I had to do the following

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From Version 23

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