Why should you be careful when choosing a sentinel value?
> Find the error: // Force a call to the paint method paint();
> Find the error:
> An application has a Button control named calcButton. Write the statement that assigns the ID "calc-button" to the calcButton control.
> Find the error: // Create a text area with 20 columns and 5 rows. JTextArea textArea = new JTextArea (20, 5);
> Find the error: JLabel label = new JLabel("Have a nice day!"); label.setImage(image) ;
> Find the error: // Create a JList and add it to a scroll pane. // Assume that array already exists. JList list = new JList(array) ; JScrollPane scrollPane = new JScrollPane(); scrollPane.add(list) ;
> Find the error: // Create a read-only text field. JTextField textField = new JTextField(10); textField.setEditable(true);
> Find the error in the following Java code. Assume that conn references a valid Connection object. // This code has an error!!! String sql = "SELECT * FROM Coffee"; Statement stmt = conn.createStatement(); ResultSet result = stmt.execute(sql);
> Find the error in the following SQL statement. SELECT * FROM Coffee WHERE Description = "French Roast Dark”
> The panel variable references a JPanel object. The intention of the following statement is to create a titled border around panel: panel.setBorder(new BorderFactory("Choices"));
> The intention of the following statement is to give the panel object a GridLayout manager with 10 columns and 5 rows: panel.setLayout(new GridLayout(10, 5));
> The following statement is in a class that uses Swing components: import java.swing.*;
> Find the error in the following program: public class FindTheError { public static void main(String[] args) { myMethod(0); } public static void myMethod(int num) { System.out.print(num + " "); myMethod(num + 1); } }
> Write functional RGB notation for a color where red=100, green=20, and blue= 255.
> What will the following code output? int apples = 0, bananas = 2, pears = 10; apples += 10; bananas *= 10; pears /= 10; System.out.println(apples + " " + bananas + " " + pears);
> Find the error: // This code has an error! RadioButton radio1 = new RadioButton("Option 1"); RadioButton radio2 = new RadioButton("Option 2"); ToggleGroup radioGroup = new ToggleGroup(); radioGroup.setToggleGroup(radio1); radioGroup.setToggleGroup(radio2
> Find the error: .button { -fx-background-color = #0000FF; }
> Find the error: // This code has an error! myImageView.setWidth(100); myImageView.setHeight(100);
> Assume hbox is an HBox container: // This code has an error! hbox.setAlignment(CENTER);
> Find the error: // This code has an error! @Override public void start(Scene primaryScene) { primaryScene.show(); }
> Find the error: try { number = Integer.parseInt(str); } catch (Exception e) { System.out.println(e.getMessage()); } catch (IllegalArgumentException e) { System.out.println("Bad number format."); } catch (NumberFormatException e) { System.out.println(str
> Find the error: catch (FileNotFoundException e) { System.out.println("File not found."); } try { File file = new File("MyFile.txt"); Scanner inputFile = new Scanner(file); }
> Find the error: // Superclass public class Vehicle { private double cost; public Vehicle(double c) { cost = c; } } // Subclass public class Car extends Vehicle { private int passengers; public Car(int p) { passengers = c; } }
> Find the error: // Superclass public class Vehicle { (Member declarations . . .) } // Subclass public class Car expands Vehicle { (Member declarations . . .) }
> Find the error: // Change the very first character of a // StringBuilder object to 'Z'. str.setCharAt(1, 'Z');
> Write a JavaFX CSS style definition that will be applied to all Label, Button, and TextField controls. The style definition should specify the following: font size: 24, font style: italic, font weight: bold.
> Find the error: int number = 99; String str; // Convert number to a string. str.valueOf(number);
> The following class definition has an error. What is it? public class MyClass { private int x; private double y; public static void setValues(int a, double b) { x = a; y = b; } }
> String[] words = { "Hello", "Goodbye" }; System.out.println(words.toUpperCase());
> int[] table = new int[10]; for (int x = 1; x
> Find the error: int[] collection = new int[−20];
> Find the error in the following class: public class FindTheError { public int square(int number) { return number * number; } public double square(int number) { return number * number; } }
> The following statement attempts to create a Rectangle object. Find the error. Rectangle box = new Rectangle;
> Find the error in the following class: public class MyClass { private int x; private double y; public void MyClass(int a, double b) { x = a; y = b; } }
> Find the error in the following method definition: // This method has an error! public static double timesTwo(double num) { double result = num * 2; }
> Find the error in the following method definition: // This method has an error! public static void sayHello(); { System.out.println("Hello"); }
> Write code that creates a Slider control. The control should be horizontally oriented and its range should be 0 through 1000. Labels and tick marks should be displayed. Major tick marks should appear at every 100th number, and minor tick marks should app
> Assume that partNumber references a String object. The following if statement should perform a case-insensitive comparison. What is wrong with it? if (partNumber.equals("BQ789W4")) available = true;
> Find the errors in the following code: // This code contains ERRORS! int choice, num1, num2; Scanner keyboard = new Scanner(System.in); do { System.out.print("Enter a number: ") ; num1 = keyboard.nextInt() ; System.out.print("Enter another number: ") ; n
> The following statement should determine whether count is outside the range of 0 through 100. What is wrong with it? if (count < 0 && count > 100)
> Find the errors in the following code: // This code contains ERRORS! // It adds two numbers entered by the user. int num1, num2; String input; char again; Scanner keyboard = new Scanner(System.in); while (again == 'y' || again == 'Y') System.out.print("E
> What does the term multitasking mean?
> Explain why computers have both main memory and secondary storage.
> What is a memory address? What is its purpose?
> Describe the steps in the fetch/decode/execute cycle.
> Internally, the CPU consists of what two units?
> List the five major hardware components of a computer system.
> Write code that creates a ListView control named snackListView. Add the following strings to the ListView: “cheeseâ€, “olivesâ€, “crackersâ€.
> Why is the computer used by so many different people, in so many different professions?
> In the following program segment, which variable is the loop control variable (also known as the counter variable) and which is the accumulator? int a, x = 0, y = 0; while (x < 10) { a = x * 2; y += a; x++; } System.out.println("The sum is " + y);
> Write a for loop that repeats seven times, asking the user to enter a number. The loop should also calculate the sum of the numbers entered.
> Write a for loop that displays every fifth number, zero through 100.
> Write a for loop that displays all of the odd numbers, 1 through 49.
> Write a for loop that displays your name 10 times.
> What will the following program segments display? 1. x = 2; y = x++; System.out.println(y); 2. x = 2; System.out.println(x++); 3. x = 2; System.out.println(−−x); 4. x = 8; y = x−−; System.out.println(y);
> Write an if-else statement that assigns 1 to x when y is equal to 100. Otherwise, it should assign 0 to x.
> Write an if-else statement that assigns 20 to the variable y if the variable x is greater than 100. Otherwise, it should assign 0 to the variable y.
> Write a JavaFX CSS style definition that will be applied to all Label controls. The style definition should specify the following: font size: 24, font style: italic, font weight: bold.
> Write an if statement that displays “Goodbye†if the variable myCharacter Âcontains the character 'D'.
> Write an if statement that assigns 0 to the variable b and assigns 1 to the variable c if the variable a is less than 10.
> Write an if statement that assigns 20 to the variable y and assigns 40 to the Âvariable z if the variable x is greater than 100.
> Write an if statement that sets the variable fees to 50 if the boolean variable max is true.
> Assume the following declaration exists in a program: String name = "James"; Write a statement that uses System.out.printf to display the value of name in a field that is 20 spaces wide.
> Assume the following variable declaration exists in a program: double number = 123456.789; Write a statement that uses System.out.printf to display the value of the number variable left-justified, with comma separators, in a field that is 20 spaces wide,
> Assume the following variable declaration exists in a program: int number = 123456; Write a statement that uses System.out.printf to display the value of the number variable in a field that is 10 spaces wide, with comma separators.
> Assume the following variable declaration exists in a program: double number = 123.456; Write a statement that uses System.out.printf to display the value of the number variable padded with leading zeros, in a field that is eight spaces wide, rounded to
> Assume the following variable declaration exists in a program: double number = 123.456; Write a statement that uses System.out.printf to display the value of the number variable rounded to one decimal place, in a field that is 10 spaces wide.
> Write an if statement that assigns 0.2 to commission if sales is greater than or equal to 10000.
> Assume gridPane is the name of a GridPane container, and button is the name of a Button control. Write a statement that adds button to gridPane at column 2, row 5.
> Assume the following variable declaration exists in a program: double number = 1234567.456; Write a statement that uses System.out.printf to display the value of the number variable formatted as: 1,234,567.46
> What will the following code display? int funny = 7, serious = 15; funny = serious * 2; switch (funny) { case 0 : System.out.println("That is funny."); break; case 30: System.out.println("That is serious."); break; case 32: System.out.println("That is se
> What is wrong with the following switch statement? // This code has errors!!! switch (temp) { case temp < 0 : System.out.println("Temp is negative."); break; case temp = 0: System.out.println("Temp is zero."); break; case temp > 0 : System.out.println("T
> Explain why you cannot convert the following if-else-if statement into a switch statement. if (temp == 100)  x = 0; else if (population > 1000)  x = 1; else if (rate < .1)  x = −1;
> Rewrite the following if-else-if statement as a switch statement. if (selection == 'A') System.out.println("You selected A."); else if (selection == 'B') System.out.println("You selected B."); else if (selection == 'C') System.out.println("You selected C
> Complete the following program skeleton by writing a switch statement that displays “one†if the user has entered 1, “two†if the user has entered 2, and “three†if the user has entered 3. If a number other than 1, 2, or 3 is entered, the progra
> Rewrite the following if-else statements as statements that use the conditional operator. 1. if (x > y)  z = 1; else  z = 20; 2. if (temp > 45)  population = base * 10; else  population = base * 2; 3. if (hours > 40)  wages *= 1.5; else  wage
> Modify the statement you wrote in response to Checkpoint3.20 so it performs a case-insensitive comparison. Data from Checkpoint 3.20: Assume the variable name references a String object. Write an if statement that displays “Do I know you?†if the Str
> Assume the variables name1 and name2 reference two different String objects, containing different strings. Write code that displays the strings referenced by these variables in alphabetical order.
> Assume the variable name references a String object. Write an if statement that displays “Do I know you?†if the String object contains “Timothyâ€.
> Write a statement, after the following code, that creates an HBox container, adds the label1, label2, and label3 controls to it, and has 10 pixels of spacing between the controls. Label label1 = new Label("One"); Label label2 = new Label("Two"); Label la
> Write an if statement that multiplies payRate by 1.5 if hours is greater than 40.
> Write an if statement that displays the message "The number is not valid" if the variable speed is outside the range 0 through 200.
> Write an if statement that displays the message "The number is valid" if the variable speed is within the range 0 through 200.
> Assume the variables a = 2, b = 4, and c = 6. Circle the T or F for each of the ­following conditions to indicate whether it is true or false.
> The following truth table shows various combinations of the values true and false connected by a logical operator. Complete the table by circling T or F to indicate whether the result of such a combination is true or false.
> The following program is used in a bookstore to determine how many discount Âcoupons a customer gets. Complete the table that appears after the program. import javax.swing.JOptionPane; public class CheckPoint { public static void main(String[] args) { i
> What will the following program display? public class CheckPoint { public static void main(String[] args) { int funny = 7, serious = 15; funny = serious % 2; if (funny != 1) { funny = 0; serious = 0; } else if (funny == 2) { funny = 10; serious = 10; } E
> Write code that tests the variable x to determine whether it is greater than 0. If x is greater than 0, the code should test the variable y to determine whether it is less than 20. If y is less than 20, the code should assign 1 to the variable z. If y is
> Write nested if statements that perform the following test: If amount1 is greater than 10 and amount2 is less than 100, display the greater of the two.
> Write an if-else statement that assigns 0 to the variable b and assigns 1 to the variable c if the variable a is less than 10. Otherwise, it should assign −99 to the variable b and assign 0 to the variable c.
> Assume your JavaFX application is in the same directory as an image file named Cat.png. Write the code to create the Image and ImageView objects you will need to display the image.
> Write an if-else statement that assigns 0.10 to commission unless sales is greater than or equal to 50000.0, in which case it assigns 0.2 to commission.
> Write an if statement that assigns 0 to x when y is equal to 20.
> On paper, write a program that will display your name on the first line; your street address on the second line; your city, state, and ZIP code on the third line; and your telephone number on the fourth line. Place a comment with today’s date at the to
> Study the following program and show what it will print on the screen. // The Works of Wolfgang public class Wolfgang { public static void main(String[] args) { System.out.print("The works of Wolfgang\ninclude "); System.out.print("the following"); Syste
> The following program will not compile because the lines have been mixed up. System.out.print("Success\n"); } public class Success { System.out.print("Success\n"); public static void main(String[] args) System.out.print("Success "); } // It's a mad, mad
> Every Java application program must have ___. a. a method named main b. more than one class definition c. one or more comments
> All Java source code filenames must end with ____. a. a semicolon b. .class c. .java d. none of the above
> On paper, write a program that will display your name on the screen. Place a Âcomment with today’s date at the top of the program. Test your program by Âentering, compiling, and running it.
> Complete the following program skeleton so it displays the message “Hello World†on the screen. public class Hello { public static void main(String[] args) { // Insert code here to complete the program } }
