OCA / OCP Practice Tests

1. Which answer choice can replace line 6 so the code continues to produce the same
   
2. output?
   
3. 3: List<String> rug = new ArrayList<>();
   
4. 4: rug.add("circle");
   
5. 5: rug.add("square");
   
6. 6: System.out.println(rug);
   
7. A. System.out.println(rug.asString);
   
8. B. System.out.println(rug.asString());
   
9. C. System.out.println(rug.toString);
   
10. D. System.out.println(rug.toString());

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1. Which best describes this code?
   
2. class Stats {
   
3. private int data;
   
4. public int getData() {
   
5. return data;
   
6. }
   
7. public void setData(int data) {
   
8. this.data = data;
   
9. }
   
10. }
    
11. A. It is a singleton.
    
12. B. It is well encapsulated.
    
13. C. It is immutable.
    
14. D. It is both well encapsulated and immutable.

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1. What design pattern or principle ensures that there will be no more than one instance
   
2. of a class?
   
3. A. Encapsulation
   
4. B. Immutability
   
5. C. Singleton
   
6. D. Static

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1. Which is the first line to fail to compile?
   
2. class Tool {
   
3. void use() { } // r1
   
4. }
   
5. class Hammer extends Tool {
   
6. private void use() { } // r2
   
7. public void bang() { } // r3
   
8. }
   
9. A. r1
   
10. B. r2
    
11. C. r3
    
12. D. None of the above

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1. Which of these classes properly implement(s) the singleton pattern?
   
2. class ExamAnswers {
   
3. private static ExamAnswers instance = new ExamAnswers();
   
4. private List<String> answers = new ArrayList<>();
   
5. public static List<String> getAnswers() {
   
6. return instance.answers;
   
7. }
   
8. }
   
9. class TestAnswers {
   
10. private static TestAnswers instance = new TestAnswers();
    
11. private List<String> answers = new ArrayList<>();
    
12. public static TestAnswers getTestAnswers() {
    
13. return instance;
    
14. }
    
15. public List<String> getAnswers() {
    
16. return answers;
    
17. }
    
18. }
    
19. A. ExamAnswers
    
20. B. TestAnswers
    
21. C. Both classes
    
22. D. Neither class

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1. What does the following print?
   
2. public class Transport {
   
3. static interface Vehicle {}
   
4. static class Bus implements Vehicle {}
   
5. public static void main(String[] args) {
   
6. Bus bus = new Bus();
   
7. boolean n = null instanceof Bus;
   
8. boolean v = bus instanceof Vehicle;
   
9. boolean b = bus instanceof Bus;
   
10. System.out.println(n + " " + v + " " + b);
    
11. }
    
12. }
    
13. A. true true true
    
14. B. false true true
    
15. C. false false false
    
16. D. None of the above

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