Tag: web technology

Quizzes (208) Questions (4176)

Questions Related to web technology

Multiple choice technology web technology

Given: interface Hungry { void munch(E x); } interface Carnivore extends Hungry {} interface Herbivore extends Hungry {} abstract class Plant {} class Grass extends Plant {} abstract class Animal {} class Sheep extends Animal implements Herbivore { public void munch(Sheep x) {} } class Wolf extends Animal implements Carnivore { public void munch(Sheep x) {} } Which of the following changes (taken separately) would allow this code to compile? (Choose all that apply.)

  1. Change the Carnivore interface to interface Carnivore<E extends Plant> extends Hungry<E> {}

  2. Change the Herbivore interface to interface Herbivore<E extends Animal> extends Hungry<E> {}

  3. Change the Sheep class to class Sheep extends Animal implements Herbivore<Plant> { public void munch(Grass x) {} }

  4. Change the Sheep class to class Sheep extends Plant implements Carnivore<Wolf> { public void munch(Wolf x) {} }

  5. Change the Wolf class to class Wolf extends Animal implements Herbivore<Grass> { public void munch(Grass x) {} }

  6. No changes are necessary
Reveal answer Fill a bubble to check yourself
B Correct answer
Full explanation
Multiple choice technology web technology

Given: public static void main(String[] args) { // INSERT DECLARATION HERE for (int i = 0; i <= 10; i++) { List row = new ArrayList(); for (int j = 0; j <= 10; j++) row.add(i * j); table.add(row); } for (List row : table) System.out.println(row); } Which statements could be inserted at // INSERT DECLARATION HERE to allow this code to compile and run? (Choose all that apply.)

  1. List<List<Integer>> table = new List<List<Integer>>();

  2. List<List<Integer>> table = new ArrayList<List<Integer>>();

  3. List<List<Integer>> table = new ArrayList<ArrayList<Integer>>();

  4. List<List, Integer> table = new List<List, Integer>();

  5. List<List, Integer> table = new ArrayList<List, Integer>();

  6. List<List, Integer> table = new ArrayList<ArrayList, Integer>();
Reveal answer Fill a bubble to check yourself
B Correct answer
Full explanation
Multiple choice technology web technology

Given: 3. import java.util.*; 4. class Business { } 5. class Hotel extends Business { } 6. class Inn extends Hotel { } 7. public class Travel { 8. ArrayList go() { 9. // insert code here 10. } 11. } Which, inserted independently at line 9, will compile? (Choose all that apply.)

  1. return new ArrayList<Inn>();

  2. return new ArrayList<Hotel>();

  3. return new ArrayList<Object>();

  4. return new ArrayList<Business>();
Reveal answer Fill a bubble to check yourself
B Correct answer
Full explanation
Multiple choice technology web technology

Which is true? (Choose all that apply.)

  1. "X extends Y" is correct if and only if X is a class and Y is an interface

  2. "X extends Y" is correct if and only if X is an interface and Y is a class

  3. "X extends Y" is correct if X and Y are either both classes or both interfaces

  4. "X extends Y" is correct for all combinations of X and Y being classes and/or interfaces
Reveal answer Fill a bubble to check yourself
C Correct answer
Full explanation
Multiple choice technology web technology

Given: 3. class A { } 4. class B extends A { } 5. public class ComingThru { 6. static String s = "-"; 7. public static void main(String[] args) { 8. A[] aa = new A[2]; 9. B[] ba = new B[2]; 10. sifter(aa); 11. sifter(ba); 12. sifter(7); 13. System.out.println(s); 14. } 15. static void sifter(A[]... a2) { s += "1"; } 16. static void sifter(B[]... b1) { s += "2"; } 17. static void sifter(B[] b1) { s += "3"; } 18. static void sifter(Object o) { s += "4"; } 19. } What is the result?

  1. -124

  2. -134

  3. -424

  4. -434

  5. -444

  6. Compilation fails
Reveal answer Fill a bubble to check yourself
D Correct answer
Full explanation
Multiple choice technology web technology

Given: 3. public class TestDays { 4. public enum Days { MON, TUE, WED }; 5. public static void main(String[] args) { 6. for(Days d : Days.values() ) 7. ; 8. Days [] d2 = Days.values(); 9. System.out.println(d2[2]); 10. } 11. } What is the result? (Choose all that apply.)

  1. TUE

  2. Wed

  3. The output is unpredictable

  4. Compilation fails due to an error on line 4

  5. Compilation fails due to an error on line 6

  6. Compilation fails due to an error on line 8
Reveal answer Fill a bubble to check yourself
B Correct answer
Full explanation
Multiple choice technology web technology

Given the proper import statement(s), and 13. PriorityQueue pq = new PriorityQueue(); 14. pq.add("2"); 15. pq.add("4"); 16. System.out.print(pq.peek() + " "); 17. pq.offer("1"); 18. pq.add("3"); 19. pq.remove("1"); 20. System.out.print(pq.poll() + " "); 21. if(pq.remove("2")) System.out.print(pq.poll() + " "); 22. System.out.println(pq.poll() + " " + pq.peek()); What is the result?

  1. 2 2 3 3

  2. 2 2 3 4

  3. 4 3 3 4

  4. 2 2 3 3 3

  5. 4 3 3 3 3

  6. 2 2 3 3 4
Reveal answer Fill a bubble to check yourself
B Correct answer
Full explanation