Ch. 1 Windows Command Prompt HW

22 Chapter I Introduction to Computers . the Internet and Java

Select a shape

Specify whether a

rectangle or ova l is filled

with color

Close button

a) Painter app runn ing on Windows

b) Painter app runn ing on Linux.

c) Painter app running on OS X.

Close - F{:l n n Painter button 1...:..-__:.-~------;..;:;;=-----------1

~lack __jJ (, Line _i) Cl Filled ~do

0 0)

Fig. 1.11 I Painter app executing in Windows 7. Lin ux and OS X.

Close button

entire drawing

Undo the last shape that was added to the drawing

[Note: Java commands are case sensitive-that is, uppercase letters are different from lowercase letters. It's important to type the name of this application as Paint­ er with a capital P. Otherwise, the application will not execute. Specifying the . class extension when using the java command results in an error. Also, if you receive the error message, "Exception in thread "main" java .lang. NoCl ass­ DefFoundError: Painter ," your system has a CLASSPATH problem. Please refer to

the Before You Begin section for instructions to help you ftx this problem.]

4. Drawing a filled yellow oval for the face. Select Yellow as the drawing color, Oval ' as the shape and check the Filled checkbox, then drag the mouse to draw a large

oval (Fig. 1.12).

1. 10 Test-Driving a j ava Appli cation 23

~~~ 1 • . ... .. 1 ( ~· -· t • ) 0 Fil led [ Und~ J

(435,295) l)

Fig. 1.1 2 I Drawing a fi lled yellow ova l for the face.

5. Drawing blue eyes. Select Blue as the drawing color, then draw two small ovals as the eyes (Fig. 1.1 3).

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l)

(37 1,131)

Fig. 1. 13 I Drawing blue eyes.

6. D rawing black eyebrows and a nose. Select Black as the drawing color and Line as the shape, then draw eyebrows and a nose (Fig. 1.14) . Lines do not have fi ll , so leaving the Filled checkbox checked has no effect when drawing lines.

24 Chapter I Introduction to Computers , the Internet and Java

Fig. 1.14 I Drawing black eyebrows and a nose.

7. Drawing a magenta mouth. Select Magenta as the drawing color and Oval as the

shape, then draw a mouth (Fig. 1.15).

(Magenta ! • ]( '-ov_a_t _......_

(435,169)

Fig. 1.1 S I Drawing a magenta mouth.

8. Drawing a yellow oval on the mouth to make a smile. Select Yellow as the drawing color, then draw an oval to change the magenta oval into a smile (Fig. 1.16) .

------

(328,252)

1. 1 I Internet and World Wide Web :ZS

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[ C l~ar J

------

Fig. 1.16 I Drawing a yel low oval on the mouth to make a sm ile.

9. Exiting the Painter application. To exit the Painter application, click the Close button (in the window's upper-right corner on Windows and the upper-left cor­ ner on Linux and OS X). Closing the window causes the Painter application to terminate.

1.11 Internet and World Wide Web In the late 1960s, ARP A-the Advanced Research Projects Agency of the United States De­ partment of Defense-rolled out plans for networking the main computer systems of ap­ proximately a dozen ARP A-funded universities and research institutions. The computers were to be connected with communications lines operating at speeds on the order of 50,000 bits per second, a stunning rate at a time when most people (of the few who even had net­ working access) were connecting over telephone lines to computers at a rate of 110 bits per second. Academic research was about to rake a giant leap forward. ARPA proceeded to im­ plement what quickly became known as the ARPANET, the precursor to today' s Internet. Today's fastest Internet speeds are on the order of billions of bits per second with trillion­ bit-per-second speeds on the horizon!

Things worked out differently from the original plan. Although the ARPANET enabled researchers to network their computers, irs main benefit proved to be the capa­ bility for quick and easy communication via what came to be known as electronic mail (e­ mail). This is true even on today's Internet, with e-mail, instant messaging, file transfer and social media such as Facebook and Twitter enabling billions of people worldwide to communicate quickly and easily.

The protocol (set of rules) for communicating over the ARPANET became known as the Transmission Control Protocol (TCP) . TCP ensured that messages, consisting of sequentially numbered pieces called packets, were properly routed from sender to receiver, arrived intact and were assembled in the correct order.

Chapter 1/painter/DrawFrame.class

                public 
                synchronized 
                class DrawFrame 
                extends javax.swing.JFrame 
                implements java.awt.event.ItemListener, java.awt.event.ActionListener {
    
                private java.awt.Color[] 
                colors;
    
                private String[] 
                colorNames;
    
                private String[] 
                shapes;
    
                private DrawPanel 
                drawPanel;
    
                private javax.swing.JButton 
                undoButton;
    
                private javax.swing.JButton 
                clearButton;
    
                private javax.swing.JComboBox 
                colorChoices;
    
                private javax.swing.JComboBox 
                shapeChoices;
    
                private javax.swing.JCheckBox 
                filledCheckBox;
    
                public void DrawFrame();
    
                public void 
                itemStateChanged(java.awt.event.ItemEvent);
    
                public void 
                actionPerformed(java.awt.event.ActionEvent);
}