4209233
Description
Quiz by bowtietigers, updated more than 1 year ago
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Created by bowtietigers
over 8 years ago
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Question 1
Question
Which of the following choices might serve as an interface for the other choices listed?
Answer
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Piano
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Drum
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Guitar
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Instrument
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FrenchHorn
Question 2
Question
Which of the following code segments causes a compile-time error?
Answer
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Airplane boeing707 = new Airplane();
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Flier boeing707 = new Flier();
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Flier boeing707 = new Airplane();
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Airplane boeing707 = new Airplane(); Flier airTraveler = boeing707;
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Airplane boeing707 = new Airplane(); Flier airTraveler; airTraveler = (Airplane) beoing707;
Question 3
Question
Consider the following code segment.
1 Airplane skyRider = new Airplane();
2 Flier skyRider2 = skyRider;
3 Athlete skyRider3 = (Athlete) skyRider2;
4 Airplane skyRider4 = (Airplane) skyRider2;
5 Flier skyRider5 = skyRider4;
Which statement above will cause a run-time error and throw an exception?
Answer
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Statement 1
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Statement 2
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Statement 3
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Statement 4
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Statement 5
Question 4
Question
Airplane c = new Airplane();
Flier f = new Airplane();
Athlete a = new SkiJumper("Ann", "Smith");
SkiJumper s = new SkiJumper("John", "Doe");
Which of the following statements is not legal?
Answer
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c.fly();
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f.fly();
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a.train(3);
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s.train(3);
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a.fly();
Question 5
Question
Airplane c = new Airplane();
Flier f = new Airplane();
Athlete a = new SkiJumper("Ann", "Smith");
SkiJumper s = new SkiJumper("John", "Doe");
Which of the following statements needs a cast?
I. f = c;
II. a = s;
III. s = a;
Answer
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I only
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II only
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III only
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I and II only
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I and III only
Question 6
Question
Suppose class C implements an interface I by implementing all of the methods of I and no further methods. Then which of the following must be true?
Answer
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All instance variables or C are public.
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All methods of C are abstract.
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All methods of C are public.
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All constants of C are public.
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All instance variables of C are private.
Question 7
Question
Which of the following statements is true about casting?
Answer
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You must cast to convert from an interface type to a class type.
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You must cast to convert from a class type to an interface type.
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You cannot cast to convert an interface type to a class type.
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You cannot cast from a class type to an interface type.
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Both a and b above are true.
Question 8
Question
Which of the following statements is true about dynamic binding?
Answer
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Dynamic binding occurs during compile time.
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Dynamic binding occurs when the appropriate overloaded method is selected.
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Dynamic binding is another name for early binding.
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In dynamic binding, the virtual machine selects the appropriate method.
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Dynamic binding occurs only when an interface declares public static final constants.
Question 9
Question
Which of the following statements about interfaces is not true?
Answer
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An interface can specify constants that can be used by all classes that implement the interface.
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An interface can specify variables that can be used by all classes that implement the interface.
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An interface can specify methods that must be defined by all classes that implement the interface.
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An interface name cannot be instantiated.
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The interface contains declarations but not implementations.
Question 10
Question
Suppose foo is an object of class C, and C implements the interface type I. Which of the following statements must be true?
Answer
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foo was constructed with the constructor of I.
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C assigns values to all constants declared in the interface I.
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C supplies an implementation for all methods of the interface I.
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foo must be declared as I foo = new C();
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All methods of I are declared as private.
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