Options A and E are the correct syntax to handle all three types of Lists in the
takeCars argument
58.
Given:
1. import java.util.*;
2. class Stuff implements Comparable {
3. int x;
4. Stuff(int x) { this.x = x; }
5. public int compareTo(Object o) { return 0; }
6. }
7. class AddStuff {
8. public static void main(String [] args) {
9. TreeSet<Stuff> ts = new TreeSet<Stuff>();
10. ts.add(new Stuff(1));
11. ts.add(new Stuff(2));
12. System.out.println(ts.size());
13. } }
What is the result?
A) 0
B) 1
C) 2
D) Compilation fails.
E) An exception is thrown at runtime.
Answer:
Option B is correct. Since compareTo always returns 0, the second add fails because
TreeSets cannot have duplicate entries.
59.
Given:
1. import java.util.*;
2. class DumpMap {
3. public static void main(String [] args) {
4. HashMap h = new HashMap();
5. h.put("a","aa"); h.put("b","bb"); h.put("c","cc");
6. Set ks = h.keySet();
7. Object [] ka1 = ks.toArray();
8. ks = new TreeSet(ks);
9. Object [] ka2 = ks.toArray();
10. System.out.println(Arrays.equals(ka1, ka2));
11. }
12. }
What is the result?
A) true
B) false
C) The output is unpredictable.
D) Compilation fails due to an error on line 8.
Answer:
Option C is correct. ka2 is sorted, but there is no guarantee what order ka1's
elements are in.
60.
Given two files.
1. package x;
2. public class X {
3. // insert code here
4. }
and.
1. package x;
2. public class Find4 {
3. public static void main(String [] args) {
4. X myX = new X();
5. myX.doX();
6. }
7. }
