Java expert please help me

QUESTION 34

Which of the following best describes Sally?

 1 

 2 public class Sally { 

 3 

 4 private double data; 

 5 

 6 public Sally(double d) { 

 7 data = d;8 } 

 9 

10 public int hashCode() { 

11 final int prime = 31; 

12 int result = 1; 

13 result = prime * result; 

14 return result;15 } 

16 

17 public boolean equals(Object obj) { 

18 if (this == obj) 

19 return true; 

20 if (obj == null) 

21 return false; 

22 if (!(obj instanceof Sally)) 

23 return false; 

24 Sally other = (Sally) obj; 

25 if (Math.abs(data - other.data) < .00001) 

26 return true; 

27 return false; 

28 } 

29 } 

		A - Sally cannot be used in a HashSet because it is not serializable
		B - Sally will not compile because to override equals, the signature must be boolean equals(Sally obj)
		C - Sally should not be used in a HashSet because equal objects may have different hash values.
		D - Sally can be used in a HashSet, but the HashSet will perform poorly because of collisions

QUESTION 35

If no locale is explicitly supplied for user messages, the system uses messages associated with US English.

True

False

QUESTION 36

You should always invoke the unlock method in the finally clause.

		true
		false

QUESTION 37

Under what conditions are locks unnecessary for multi-threaded programs?

		A- when the threads are different classes
		B- when the threads do not share data
		C - when the shared data only has a single method
		D - when the threads are all of the same class