When you use a timer you need to define a class that impleme

When you use a timer, you need to define a class that implements the ____ interface.

TimerListener

TimerActionListener

ActionListener

StartTimerListener

1 points   

QUESTION 3

The documentation for the JSlider class lists ____ inherited methods.

less than 5

about 25

about 250

over 2500

1 points   

QUESTION 4

Which component can be added to a menu?


I JMenuBar
II JMenu
III JMenuItem

I

I and II

II and III

I, II and III

1 points   

QUESTION 5

Which layout manager places objects left-to-right, and creates a new row only if when the current row cannot accommodate another object?

FlowLayout

BorderLayout

BoxLayout

GridLayout

1 points   

QUESTION 6

What does the MouseAdapter class provide?

The MouseAdapter class implements all of the methods of the MouseListener interface as do nothing methods.

The MouseAdapter class allows your program to accept input from multiple mice.

The MouseAdapter class implements all of the methods of the ActionListener interface as do nothing methods.

A class can implement the MouseAdapter class to handle mouse events.

1 points   

QUESTION 7

What is known for certain from this correct code excerpt?

ActionListener openListener = new FileOpenListener();
JMenuItem fileOpen = new JMenuItem(\"Open File\");
fileOpen.addActionListener(openListener);

fileOpen will open a file dialog when clicked

The fileOpen menu item will be visible

The FileOpenListener class implements the ActionListener interface

The openListener object will only listen to the fileOpen object

1 points   

QUESTION 8

Given four JRadioButton objects in a ButtonGroup, how many radio buttons can be selected at the same time?

1

2

4

3

1 points   

QUESTION 9

The statement that would add smallButton to the button group in the following code is _________.


JRadioButton smallButton = new JRadioButton(\"Small\");
ButtonGroup group = new ButtonGroup();

group.add(new smallButton);

group.add(smallButton);

smallButton.add();

You cannot add smallButton to the button group.

1 points   

QUESTION 10

What is wrong with the following code?


class ExitListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
System.exit(0);
}
}


ActionListener exitListener = new ExitListener();
JMenu exitMenu = new JMenu(\"Exit\");
exitMenu.addActionListener(exitListener);
JMenuBar menuBar = new JMenuBar();
menuBar.add(exitMenu);

The ExitListener class is not public

You cannot attach a listener to a menu, only to a menu item

You cannot add a menu to the menu bar, only a menu item

You need to use a menu listener, not an action listener

1 points   

QUESTION 11

Consider the following code snippet:


final RectangleComponent component = new RectangleComponent();


MouseListener listener = new MousePressListener();
component.addMouseListener(listener);
______________
mystery.add(component);


mystery.setSize(FRAME_WIDTH, FRAME_HEIGHT);
mystery.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mystery.setVisible(true);

Which of the following statements completes this code?

JPanel mystery = new JPanel();

JComponent mystery = new JComponent();

Frame mystery = new Frame();

JFrame mystery = new JFrame();

1 points   

QUESTION 12

What type of object can be added into a JComboBox by the addItem method?

Object

String

JRadioButton

any non-primitive type

1 points   

QUESTION 13

Consider the code snippet below:


public class RectangleComponent extends JComponent
{
private static final int RECTANGLE_WIDTH = 20;
private static final int RECTANGLE_HEIGHT = 30;


private int xLeft;
private int yTop;


public RectangleComponent()
{
xLeft = 0;
yTop = 0;
}


public void paintComponent(Graphics g)
{
g.fillRect(xLeft, yTop, RECTANGLE_WIDTH, RECTANGLE_HEIGHT);
}


public void moveRectangleBy(int dx, int dy)
{
xLeft = xLeft + dx;
yTop = yTop + dy;
repaint();
}
}


Which statement(s) causes the rectangle to appear at an updated location?

repaint();

public void moveRectangleBy(int dx, int dy);

xLeft = xLeft + dx;
yTop = yTop + dy;

xLeft = 0;
yTop = 0;

1 points   

QUESTION 14

When a menu item is selected, what type of event does it send?

ActionEvent

ChangeEvent

ItemEvent

SelectionEvent

1 points   

QUESTION 15

To create a _____ layout, you supply the number of rows and columns in the constructor, then add the components, row by row, left to right.

border

grid

grid bag

boxed

1 points   

QUESTION 16

Consider the following code snippet:


class MyListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
System.out.println(event);
}
}


Timer t = new Timer(interval, listener);
t.start();

What is wrong with this code?

The Timer object should be declared before the MyListener class.

The listener must be declared as new MyListener().

The Timer object must be declared as final.

The word listener should be change to MyListener.

1 points   

QUESTION 17

Which of the following methods returns the object that was selected in the JComboBox?

getSelected

getItem

getChoice

getSelectedItem

1 points   

QUESTION 18

The code below will not compile successfully unless the argument to the makeMenuItem method is final. Why not?


public JMenuItem makeMenuItem(final String menuLabel)
{
JMenuItem mi = new JMenuItem(menuLabel);
class MyMenuListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
doSomethingElse();
System.out.println(menuLabel);
}
}
mi.addActionListener(new MyMenuListener());
return mi;
}

JMenuItem labels must be final

This prevents the menuLabel argument from being modified

Because a local variable is being accessed from an inner classes

Because the String class is final

1 points   

QUESTION 19

You wish to detect when the mouse is moved into a graphical component. Which methods of the associated MouseListener interface will provide this information?

mouseMoved

mouseEntered

mouseOver

mouseIncoming

1 points   

QUESTION 20

The event that is generated by a slider when its value changes is of type _____.

ActionEvent

ChangeEvent

ItemEvent

MouseEvent

		TimerListener
		TimerActionListener
		ActionListener
		StartTimerListener

Solution

[2] ActionListener interface
[3] about 250 inherited methods
[4] all are component to a menu.
[5] FlowLayout
[6] The MouseAdapter class implements all of the methods of the MouseListener interface as do nothing methods
[7] The FileOpenListener class implements the ActionListener interface
[8] 1 button at a time
[9] group.add(smallButton)
[10] You cannot attach a listener to a menu, only to a menu item
[11] JFrame mystery = new JFrame();
[12] any non-primitive type
[13] xLeft = xLeft + dx;
yTop = yTop + dy;
[14] ActionEvent
[15] grid
[16] The listener must be declared as new MyListener().
[17] getSelectedItem
[18] Because a local variable is being accessed from an inner classes
[19] mouseEntered
[20] ChangeEvent