单项选择题
1. import java.util.*；
2. public class Example {
3. public static void main（String[] args） {
4. // insert code here
5. set.add（new integer（2））；
6. set.add（new integer（l））；
7. System.out.println（set）；
8. }
9. }
Which code， inserted at line 4， guarantees that this program will output [1，2]？ （）
A. Set set = new TreeSet（）；
B. Set set = new HashSet（）；
C. Set set = new SortedSet（）；
D. List set = new SortedList（）；
E. Set set = new LinkedHashSet（）；
相关考题
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多项选择题
10. interface Jumper { public void jump（）； } ...... 20. class Animal {} ...... 30. class Dog extends Animal { 31. Tail tail； 32. } ...... 40. class Beagle extends Dog implements Jumper { 41. public void jump（） { } 42. } ....... 50. class Cat implements Jumper { 51. public void jump（） { } 52. } Which three are true？（）
A. Cat is-a Animal
B. Cat is-a Jumper
C. Dog is-a Animal
D. Dog is-a Jumper
E. Cat has-a Animal
F. Beagle has-a Tail
G. Beagle has-a Jumper -
多项选择题
Whichtwoaretrueabouthas-aandis-arelationships？（）
A. Inheritance represents an is-a relationship.
B. Inheritance represents a has-a relationship.
C. Interfaces must be used when creating a has-a relationship.
D. Instance variables can be used when creating a has-a relationship. -
多项选择题
Whichfouraretrue？（）
A. Has-a relationships should never be encapsulated.
B. Has-a relationships should be implemented using inheritance.
C. Has-a relationships can be implemented using instance variables.
D. Is-a relationships can be implemented using the extends keyword.
E. Is-a relationships can be implemented using the implements keyword.
F. An array or a collection can be used to implement a one-to-many has-a relationship.
G. The relationship between Movie and Actress is an example of an is-a relationship.
