1. 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.
2. Name three subclasses of the Component class.
Box.Filler, Button, Canvas, Checkbox, Choice, Container, Label, List, Scrollbar, or TextComponent
3. What is the Gregorian Calendar class?
The GregorianCalendar provides support for traditional Western calendars.
4. Which Container method is used to cause a container to be laid out and redisplayed?
validate()
5. What is the purpose of the Runtime class?
The purpose of the Runtime class is to provide access to the Java runtime system.
6. 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.
7. 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.
8. What is the argument type of a program’s main() method?
A program’s main() method takes an argument of the String[] type.
9. Which Java operator is right associative?
The = operator is right associative.
10. What is the Locale class?
The Locale class is used to tailor program output to the conventions of a particular geographic, political, or cultural region.
11. Can a double value be cast to a byte?
Yes, a double value can be cast to a byte.
12. What is the difference between a break statement and a continue statement?
A break statement results in the termination of the statement to which it applies (switch, for, do, or while). A continue statement is used to end the current loop iteration and return control to the loop statement.
13. 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.
14. What method is invoked to cause an object to begin executing as a separate thread?
The start() method of the Thread class is invoked to cause an object to begin executing as a separate thread.
15. Name two subclasses of the TextComponent class.
TextField and TextArea
16. What is the advantage of the event-delegation model over the earlier event-inheritance model?
The event-delegation model has two advantages over the event-inheritance model. First, it enables event handling to be handled by objects other than the ones that generate the events (or their containers). This allows a clean separation between a component’s design and its use. The other advantage of the event-delegation model is that it performs much better in applications where many events are generated. This performance improvement is due to the fact that the event-delegation model does not have to repeatedly process unhandled events, as is the case of the event-inheritance model.
17. Which containers may have a MenuBar?
Frame
18. How are commas used in the intialization and iteration parts of a for statement?
Commas are used to separate multiple statements within the initialization and iteration parts of a for statement.
19. What is the purpose of the wait(), notify(), and notifyAll() methods?
The wait(),notify(), and notifyAll() methods are used to provide an efficient way for threads to wait for a shared resource. When a thread executes an object’s wait() method, it enters the waiting state. It only enters the ready state after another thread invokes the object’s notify() or notifyAll() methods.
20. What is an abstract method?
An abstract method is a method whose implementation is deferred to a subclass.
2. Name three subclasses of the Component class.
Box.Filler, Button, Canvas, Checkbox, Choice, Container, Label, List, Scrollbar, or TextComponent
3. What is the Gregorian Calendar class?
The GregorianCalendar provides support for traditional Western calendars.
4. Which Container method is used to cause a container to be laid out and redisplayed?
validate()
5. What is the purpose of the Runtime class?
The purpose of the Runtime class is to provide access to the Java runtime system.
6. 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.
7. 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.
8. What is the argument type of a program’s main() method?
A program’s main() method takes an argument of the String[] type.
9. Which Java operator is right associative?
The = operator is right associative.
10. What is the Locale class?
The Locale class is used to tailor program output to the conventions of a particular geographic, political, or cultural region.
11. Can a double value be cast to a byte?
Yes, a double value can be cast to a byte.
12. What is the difference between a break statement and a continue statement?
A break statement results in the termination of the statement to which it applies (switch, for, do, or while). A continue statement is used to end the current loop iteration and return control to the loop statement.
13. 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.
14. What method is invoked to cause an object to begin executing as a separate thread?
The start() method of the Thread class is invoked to cause an object to begin executing as a separate thread.
15. Name two subclasses of the TextComponent class.
TextField and TextArea
16. What is the advantage of the event-delegation model over the earlier event-inheritance model?
The event-delegation model has two advantages over the event-inheritance model. First, it enables event handling to be handled by objects other than the ones that generate the events (or their containers). This allows a clean separation between a component’s design and its use. The other advantage of the event-delegation model is that it performs much better in applications where many events are generated. This performance improvement is due to the fact that the event-delegation model does not have to repeatedly process unhandled events, as is the case of the event-inheritance model.
17. Which containers may have a MenuBar?
Frame
18. How are commas used in the intialization and iteration parts of a for statement?
Commas are used to separate multiple statements within the initialization and iteration parts of a for statement.
19. What is the purpose of the wait(), notify(), and notifyAll() methods?
The wait(),notify(), and notifyAll() methods are used to provide an efficient way for threads to wait for a shared resource. When a thread executes an object’s wait() method, it enters the waiting state. It only enters the ready state after another thread invokes the object’s notify() or notifyAll() methods.
20. What is an abstract method?
An abstract method is a method whose implementation is deferred to a subclass.
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