Terms & Concepts
These are some of the terms and concepts you should know or learn. Some will be obvious, others will be confusing for a while. The more you can learn and identify, the easier programming will be...especially when Mr. Meinzen talks about them.
Basic Terms/Concepts |
Abstract Terms/Concepts |
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Program Walkthrough (based upon PetRockGUI.java)
After Mr. Meinzen demonstrates the program walkthrough, answer the following questions:
PetRockGUI.java
1 import javax.swing.*; 2 import java.awt.*; 3 import java.awt.event.*; 4 public class PetRockGUI extends JPanel implements ActionListener 5 { 6 private JFrame frameObject; 7 private JButton buttonObject; 8 private JLabel labelObject; 9 private int length; 10 private int width; 11 private String name; 12 public static void main(String a[]) 13 { 14 PetRockGUI game = new PetRockGUI(); 15 } 16 public PetRockGUI() 17 { 18 length = 50; 19 width = 100; 20 name = "Mr. Meinzen's PetRock"; 21 Font niceFont = new Font("Courier New", Font.PLAIN, 24); 22 labelObject = new JLabel("My name is "+name); 23 labelObject.setFont(niceFont); 24 labelObject.setForeground(Color.RED); 25 this.add(labelObject); 26 buttonObject = new JButton("Click me to flip"); 27 buttonObject.addActionListener(this); 27 this.add(buttonObject); 29 frameObject = new JFrame("My First Graphical Application"); 30 frameObject.setSize(500, 500); 31 frameObject.setLayout(null); 32 frameObject.setContentPane(this); 33 frameObject.setVisible(true); 34 } 35 public void paintComponent(Graphics g) 36 { 37 super.paintComponent(g); 38 g.setColor(Color.GREEN); 39 g.fillRect(50,150,length,width); 40 } 41 public void flip() 42 { 43 int temp = length; 44 length = width; 45 width = temp; 46 } 47 public void actionPerformed(ActionEvent e) 48 { 49 flip(); 50 repaint(); 51 } 52 }
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After hitting the "Hammer1" button, what happens and which line does the computer start on?
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After hitting the “Hammer2” button, what happens and which line does the computer start on?
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Name all the methods in the class.
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Name all the variables and their Types.
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What is the difference between starting with a capital letter and lower-case letter (i.e. when should you start with a capital letter and when should you start with a lower case letter?)
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What is the difference between a Class and an object?
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Which line(s) have the following:
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a declaration for a Button
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an instantiation for a Button
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listens for clicks on a Button
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puts a Button on the screen
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find 3 lines that have a literal being assigned to a variable
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find a line where a variable is declared inside a method
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which lines have a matching method declaration and method call
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find a line that uses a qualified name
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