ADVANCED JAVA PART 3

ADVANCED JAVA PART 3

41. What is the difference between a MenuItem and a CheckboxMenuItem?

The CheckboxMenuItem class extends the MenuItem class to support a menu item that may be

checked or unchecked.

42. What is a task's priority and how is it used in scheduling?

A task's priority is an integer value that identifies the relative order in which it should be executed

with respect to other tasks. The scheduler attempts to schedule higher priority tasks before lower

priority tasks.

43. What class is the top of the AWT event hierarchy?

The java.awt.AWTEvent class is the highest-level class in the AWT event-class hierarchy.

44. When a thread is created and started, what is its initial state?

A thread is in the ready state after it has been created and started.

45. Can an anonymous class be declared as implementing an interface and extending a

class?

An anonymous class may implement an interface or extend a superclass, but may not be declared to

do both.

46. What is the immediate superclass of Menu?

MenuItem.

47. What is the purpose of finalization?

The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup

processing before the object is garbage collected.

48. Which class is the immediate superclass of the MenuComponent class?

Object.

49. What invokes a thread's run() method?

After a thread is started, via its start() method or that of the Thread class, the JVM invokes the

thread'srun() method when the thread is initially executed.

50. What is the difference between the Boolean & operator and the && operator?

If an expression involving the Boolean & operator is evaluated, both operands are evaluated. Then

the &operator is applied to the operand. When an expression involving the && operator is evaluated,

the first operand is evaluated.

If the first operand returns a value of true then the second operand is evaluated. The && operator is

then applied to the first and second operands. If the first operand evaluates to false, the evaluation of

the second operand is skipped.

51. Name three subclasses of the Component class.

Box.Filler, Button, Canvas, Checkbox, Choice, Container, Label, List, Scrollbar,

or TextComponent.

52. What is the GregorianCalendar class?

The GregorianCalendar class provides support for traditional Western calendars.

53. Which Container method is used to cause a container to be laid out and redisplayed?

validate() method is used to cause a container to be laid out and redisplayed.

54. What is the purpose of the Runtime class?

The purpose of the Runtime class is to provide access to the Java runtime system.

55. How many times may an object's finalize() method be invoked by the garbage collector?

An object's finalize() method may only be invoked once by the garbage collector.

56. What is the purpose of the finally clause of a try-catch-finally statement?

The finally clause is used to provide the capability to execute code no matter whether or not an

exception is thrown or caught.

57. What is the argument type of a program's main() method?

A program's main() method takes an argument of the String[] type.

58. Which Java operator is right associative?

The = operator is right associative.

59. Can a double value be cast to a byte?

Yes, a double value can be cast to a byte.

60. What must a class do to implement an interface?

It must provide all of the methods in the interface and identify the interface in its implements clause.