This document contains a quiz on Java concepts with 3 multiple choice questions. The first question asks which collection interface TreeMap implements, with the correct answer being SortedMap. The second question asks how garbage collection can be forced, with the answer being that it cannot be forced. The third question provides code assigning dates to variables and changing a year, asking what the output will be. The correct answer is that d1 and d2 will have different years printed, with d2's year changed in the method.

1. Quiz Java
Geek Time - Janvier 2017
Khaled HALLEB
Consultant - OLBATI

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Question 1
TreeMap class is used to implement which collection interface. Select the one correct answer
A. Set
B. SortedSet
C. List
D. Tree
E. SortedMap

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Question 2
Q2. How can you force garbage collection of an object?
A. Garbage collection cannot be forced.
B. Call System.gc().
C. Call System.gc() passing in a reference to the object to be garbage collected.
D. Call Runtime.gc().
E. Set all references to the object to new values(null, for example).

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Question 3
3. Given the following code:
public class Example {
public static void main(String args[]) {
Date d1 = new Date (99, 11, 31);
Date d2 = new Date (99, 11, 31);
method(d1, d2);
System.out.println("d1 is " + d1
+ "nd2 is " + d2);
}
public static void method(Date d1, Date d2) {
d2.setYear (100);
d1 = d2;
}}
Which one or more of the following correctly describe the behavior when this
program is compiled and run?
a) compilation is successful and the output is:
d1 is Fri December 31 00:00:00 GMT 1999
d2 is Fri December 31 00:00:00 GMT 1999
b) compilation is successful and the output is:
d1 is Fri December 31 00:00:00 GMT 1999
d2 is Sun December 31 00:00:00 GMT 2000
c) compilation is successful and the output is:
d1 is Sun December 31 00:00:00 GMT 2000
d2 is Sun December 31 00:00:00 GMT 2000
d) the assignment 'd1 = d2' is rejected by the compiler because the Date class cannot overload the operator '='.
e) the expression (d1 is " + d1 + "nd2 is " + d2) is rejected by the compiler because the Date class cannot overload the
operator '+'.

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Réponse 1
TreeMap class is used to implement which collection interface. Select the one correct answer
Correct Answer: E

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Réponse 2
Q2. How can you force garbage collection of an object?
Correct Answer: A

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Réponse 3
3. Given the following code:
public class Example {
public static void main(String args[]) {
Date d1 = new Date (99, 11, 31);
Date d2 = new Date (99, 11, 31);
method(d1, d2);
System.out.println("d1 is " + d1
+ "nd2 is " + d2);
}
public static void method(Date d1, Date d2) {
d2.setYear (100);
d1 = d2;
}}
Correct Answer: B

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Thanks !
Any questions ?
khaled.halleb@olbati.com