AWT: Controls, Layout Managers and Menus - 2

31) Which components are used to get text input from the user.

Ans : TextField and TextArea.

32) Which object is needed to group Checkboxes to make them exclusive?

Ans : CheckboxGroup.

33) Which of the following components allow multiple selections?

1.      Non-exclusive Checkboxes.

2.      Radio buttons.

3.      Choice.

4.      List.

Ans : a and d.

34) What are the types of Checkboxes and what is the difference between them?

Ans : Java supports two types of Checkboxes. They are : Exclusive and Non-exclusive.

In case of exclusive Checkboxes, only one among a group of items can be selected at a time. I f an item from the group is selected, the checkbox currently checked is deselected and the new selection is highlighted. The exclusive Checkboxes are also called as Radio buttons.

The non-exclusive checkboxes are not grouped together and each one can be selected independent of the other.

35) What is a Layout Manager and what are the different Layout Managers available in java.awt and what is the default Layout manager for the panal and the panal subclasses?

Ans: A layout Manager is an object that is used to organize components in a container.

The different layouts available in java.awt are :

FlowLayout, BorderLayout, CardLayout, GridLayout and GridBag Layout.

The default Layout Manager of Panal and Panal sub classes is FlowLayout".

36) Can I exert control over the size and placement of components in my interface?

Ans : Yes.

myPanal.setLayout(null);

myPanal.setbounds(20,20,200,200);

37) Can I add the same component to more than one container?

Ans : No. Adding a component to a container automatically removes it from any previous parent(container).

38) How do I specify where a window is to be placed?

Ans : Use setBounds, setSize, or setLocation methods to implement this.

• setBounds(int x, int y, int width, int height)
• setBounds(Rectangle r)
• setSize(int width, int height)
• setSize(Dimension d)
• setLocation(int x, int y)
• setLocation(Point p)

39) How can we create a borderless window?

Ans : Create an instance of the Window class, give it a size, and show it on the screen.

eg. Frame aFrame = ......

Window aWindow = new Window(aFrame);

aWindow.setLayout(new FlowLayout());

aWindow.add(new Button("Press Me"));

aWindow.getBounds(50,50,200,200);

aWindow.show();

40) Can I create a non-resizable windows? If so, how?

Ans: Yes. By using setResizable() method in class Frame.

41) What is the default Layout Manager for the Window and Window subclasses (Frame,Dialog)?

Ans : BorderLayout().

42) How are the elements of different layouts organized?

Ans : FlowLayout : The elements of a FlowLayout are organized in a top to bottom, left to right fashion.

BorderLayout : The elements of a BorderLayout are organized at the

borders (North, South, East and West) and the center of a

container.

CardLayout : The elements of a CardLayout are stacked, one on top of the other, like a deck of cards.

GridLayout : The elements of a GridLayout are of equal size and are laid out using the square of a grid.

GridBagLayout : The elements of a GridBagLayout are organized according to a grid.However, the elements are of different sizes and may occupy

more than one row or column of the grid. In addition, the rows and columns may have different sizes.

43) Which containers use a BorderLayout as their default layout?

Ans : The Window, Frame and Dialog classes use a BorderLayout as their default layout.

44) Which containers use a FlowLayout as their default layout?

Ans : The Panel and the Applet classes use the FlowLayout as their default layout.

45) What is the preferred size of a component?

Ans : The preferred size of a component size that will allow the component to display normally.

46) Which method is method to set the layout of a container?

1.      startLayout( )

2.      initLayout( )

3.      layoutContainer( )

4.      setLayout( )

Ans : d.

47) Which method returns the preferred size of a component?

1.      getPreferredSize( )

2.      getPreferred( )

3.      getRequiredSize( )

4.      getLayout( )

Ans : a.

48) Which layout should you use to organize the components of a container in a tabular form?

1.      CardLayout

2.      BorederLayout

3.      FlowLayout

4.      GridLayout

Ans : d.

49) An application has a frame that uses a Border layout manager. Why is it probably not a good idea to put a vertical scroll bar at North in the frame?

1.      The scroll bar’s height would be its preferred height, which is not likely to be enough.

2.      The scroll bar’s width would be the entire width of the frame, which would be much wider than necessary.

3.      Both a and b.

4.      Neither a nor b. There is no problem with the layout as described.

Ans : c.

50) What is the default layouts for a applet, a frame and a panel?

Ans : For an applet and a panel, Flow layout is the default layout, whereas Border layout is default layout for a frame.

51) If a frame uses a Grid layout manager and does not contain any panels, then all the components within the frame are the same width and height.

1.      True

2.      False.

Ans : a.

52) If a frame uses its default layout manager and does not contain any panels, then all the components within the frame are the same width and height.

1.      True

2.      False.

Ans : b.

53) With a Border layout manager, the component at Center gets all the space that is left over, after the components at North and South have been considered.

1.      True

2.      False

Ans : b.

54) An Applet has its Layout Manager set to the default of FlowLayout. What code would be the correct to change to another Layout Manager?

1.      setLayoutManager(new GridLayout());

2.      setLayout(new GridLayout(2,2));

3.      setGridLayout(2,2,))

4.      setBorderLayout();

Ans : b.

55) How do you indicate where a component will be positioned using Flowlayout?

a) North, South,East,West
b) Assign a row/column grid reference
c) Pass a X/Y percentage parameter to the add method
d) Do nothing, the FlowLayout will position the component

Ans :d.

56) How do you change the current layout manager for a container?

a) Use the setLayout method
b) Once created you cannot change the current layout manager of a component
c) Use the setLayoutManager method
d) Use the updateLayout method

Ans :a.

57)When using the GridBagLayout manager, each new component requires a new instance of the GridBagConstraints class. Is this statement true or false?

a) true
b) false

Ans : b.

58) Which of the following statements are true?

a)The default layout manager for an Applet is FlowLayout
b) The default layout manager for an application is FlowLayout
c) A layout manager must be assigned to an Applet before the setSize method is called
d) The FlowLayout manager attempts to honor the preferred size of any components

Ans : a and d.

59) Which method does display the messages whenever there is an item selection or deselection of the CheckboxMenuItem menu?

Ans : itemStateChanged method.

60) Which is a dual state menu item?

Ans : CheckboxMenuItem.

61) Which method can be used to enable/diable a checkbox menu item?

Ans : setState(boolean).

62) Which of the following may a menu contain?

1.      A separator

2.      A check box

3.      A menu

4.      A button

5.      A panel

Ans : a and c.

63) Which of the following may contain a menu bar?

1.      A panel

2.      A frame

3.      An applet

4.      A menu bar

5.      A menu

Ans : b

64) What is the difference between a MenuItem and a CheckboxMenuItem?

Ans : The CheckboxMenuItem class extends the MenuItem class to support a menu item

that may be checked or unchecked.

65) Which of the following are true?

1.      A Dialog can have a MenuBar.

2.      MenuItem extends Menu.

3.      A MenuItem can be added to a Menu.

4.      A Menu can be added to a Menu.

Ans : c and d.