Questions
---------
1. The program Problem.java doesn't compile. What do you need to do
to make it compile? Why?
[.../tutorial/java/javaOO/QandE-1dot1/Problem.java]
ANSWER: Add "final" in front of the declaration of the <code>timer</code>
variable. As it says in "Other Facts about Nested Classes",
"A nested class declared within a method...has access to any
final, local variables in scope."
2. Use the 1.3 API documentation for the Box class (in the
javax.swing package) to help you answer the following questions.
a. What static nested class does Box define?
ANSWER: Box.Filler
b. What inner class does Box define?
ANSWER: Box.AccessibleBox
c. What is the superclass of Box's inner class?
ANSWER: [java.awt.]Container.AccessibleAWTContainer
d. Which of Box's nested classes can you use from any class?
ANSWER: Box.Filler
e. How do you create an instance of Box's Filler class?
ANSWER:
new Box.Filler(minDimension, prefDimension, maxDimension)
3. What kind of nested class is most appropriate for each of the following
situations? [PENDING: can we make that clearer? Is there a term
for this kind of one-to-one matching question?]
a. The only users of this nested class will be instances of
the enclosing class or instances of the enclosing class's
subclasses.
ANSWER: B
b. Anyone can use this nested class.
ANSWER: C
c. Only instances of the declaring class need to use this nested
class, and a particular instance might use it several times.
ANSWER: F
d. This tiny nested class is used just once, to create an
object that implements an interface.
ANSWER: A
e. This nested class has information about its enclosing class
(not about instances of the enclosing class) and is used
only by its enclosing class and perhaps their subclasses.
ANSWER: D
f. Like e, but not intended to be used by subclasses.
ANSWER: E
A. anonymous inner class
B. protected inner class
C. public static nested class
D. protected static nested class
E. private static nested class
F. private inner class
Exercises
---------
1. First, get the source file InnerClassDemo.java.
[.../tutorial/java/javaOO/QandE-1dot2/InnerClassDemo.java]
a. Compile and run InnerClassDemo. If you have problems, see
Compiling and Running Swing Programs
[http://docs.oracle.com/javase/javatutorials/tutorialJWS/uiswing/start/swingStart.html].
ANSWER: N/A. [This step is here just to make sure they can compile
and run Swing programs, before they start trying to change
the programs.]
b. Make a copy of InnerClassDemo. Add to it an inner class named
MyActionListener that implements the ActionListener interface
[http://java.sun.com/products/jdk/1.3/docs/api/java/awt/event/ActionListener.html].
The ActionListener interface defines a single method. Put the
following code into your implementation of the method:
quit();
Delete the "//" in front of the following line of code:
//button.addActionListener(new MyActionListener());
Now compile and run the program. What is the difference in
behavior between this version and the previous version of
InnerClassDemo?
ANSWER: See InnerClassDemo2.java
[.../tutorial/java/javaOO/QandE-1dot2/InnerClassDemo2.java]
In this version, the button actually *does* something
(makes the program exit).
c. Make a copy of the program you created for b. Change your
ActionListener implementation to be an anonymous inner class.
Hint: The program already has another anonymous inner class
(a WindowAdapter), which you can look at for syntax help.
ANSWER: See InnerClassDemo3.java
[.../tutorial/java/javaOO/QandE-1dot2/InnerClassDemo3.java]
2. Get the file Class1.java
[.../tutorial/java/javaOO/QandE-1dot1/Class1.java].
a. Compile and run Class1. What is the output?
ANSWER:
InnerClass1: getString invoked.
InnerClass1: getAnotherString invoked.
b. Create a file called Class2.java that defines subclasses
of both Class1 and its inner class, InnerClass1. (Call the
subclasses Class2 and InnerClass2, respectively.) InnerClass2
should override the getAnotherString method to return
"InnerClass2 version of getAnotherString invoked".
Class2 should define one constructor and one method:
- A no-argument constructor that initializes the inherited
<code>ic</code>
instance variable to be an instance of InnerClass2.
- A <code>main</code> method that creates an instance
of Class2 and invokes displayStrings on that instance.
What is the output when you run Class2?
ANSWER:
InnerClass1: getString invoked.
InnerClass2 version of getAnother String invoked.
See Class2.java
[.../tutorial/java/javaOO/QandE-1dot1/Class2.java]
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12---Learning-Java.zip_it （1822个子文件） 
TOC.auto 11KB MultiplicationTable.class 3KB Card.class 2KB Card.class 2KB Card2.class 2KB Card2.class 2KB Planet.class 2KB CharSequenceDemo.class 2KB CharSequenceDemo.class 2KB CountVowels.class 2KB Anagram.class 2KB Anagram.class 2KB MaxVariablesDemo.class 2KB StackOfInts.class 2KB BoxDemo.class 2KB Palindrome.class 1KB StringSwitchDemo.class 1KB Alpha.class 1KB CharacterDemo.class 1KB TestFormat.class 1KB Stack2.class 1KB Rank.class 1KB NumberDemo.class 1KB Unboxing.class 1KB TrigonometricDemo.class 1KB ArrayDemo.class 1KB ArrayOfArraysDemo.class 1KB DataStructure.class 1KB SwitchDemoFallThrough.class 1KB BasicMathDemo.class 1KB MinVariablesDemo.class 1KB Bicycle.class 1KB EnumTest.class 1KB Cat.class 1KB ValueOfDemo.class 1KB ComputeInitials.class 1KB InstanceofDemo.class 1KB ComputeResult.class 1KB Bicycle.class 1KB BreakWithLabelDemo.class 1017B AClass.class 1013B RectanglePlus.class 1002B Day.class 1001B DecimalFormatDemo.class 980B FillerTest.class 971B ExponentialDemo.class 960B ContinueDemo.class 927B BreakDemo.class 914B Class1.class 911B ToStringDemo.class 901B DeltaOne.class 893B SwitchDemo.class 891B RoadBike.class 879B MountainBike.class 878B SwitchDemo2.class 870B ArrayOfArraysDemo2.class 861B Suit.class 859B FilenameDemo.class 844B ContinueWithLabelDemo.class 843B RegionMatchesDemo.class 832B Cats.class 831B StackOfInts$StepThrough.class 824B Class1.class 815B FPAdder.class 811B Stack.class 810B Rectangle.class 810B Rectangle.class 810B EnhancedForDemo.class 808B DisplayDeck2.class 791B AlphaTwo.class 790B DisplayDeck.class 786B DisplayDeck.class 786B AbstractClassTest.class 779B Rectangle.class 775B MultiDimArrayDemo.class 775B Filename.class 772B Animal.class 764B IfElseDemo.class 754B StackTest2.class 752B DataStructure$InnerEvenIterator.class 749B StringDemo.class 738B ArrayDemo.class 727B MinDemo.class 718B ThisHappens.class 712B Card3.class 701B StackTest.class 698B Adder.class 694B WhatHappens.class 693B WhileDemo.class 680B DoWhileDemo.class 680B ForDemo.class 674B ArrayOfStringsDemo.class 674B ComparisonDemo.class 662B DeltaTwo.class 655B Deck2.class 635B ConcatDemo.class 631B Deck.class 630B ArrayCopyDemo.class 630B ArrayCopyDemo.class 630B Deck.class 630B共 1822 条
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