Tag: programming languages

Questions Related to programming languages

Given: 11. public static void main(String[] args) { 12. String str = “null’; 13. if (str == null) { 14. System.out.println(”null”); 15. } else (str.length() == 0) { 16. System.out.println(”zero”); 17. } else { 18. System.out.println(”some”); 19. } 20. } ‘What is the result?
technology programming languages

  1. null

  2. zero

  3. some

  4. Compilation fails.

  5. An exception is thrown at runtime.

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Correct Option: D

Given: 25.intx=12; 26. while (x < 10) { 27. x--; 28. } 29. System.out.print(x); What is the result?
technology programming languages

  1. 0

  2. 10

  3. 12

  4. Line 29 will never be reached.

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Correct Option: C

Click the Exhibit button. Class TestException 1. public class TestException extends Exception { 2. } Class A: 1. public class A { 2. 3. public String sayHello(String name) throws TestException { 4. 5. if(name == null) { 6. throw new TestException(); 7. } 8. 9. return “Hello “+ name; 10. } 11. 12. } A programmer wants to use this code in an application: 45. A a=new A(); 46. System.out.println(a.sayHello(”John”)); Which two are true? (Choose two.)
technology programming languages

  1. Class A will not compile.

  2. Line 46 can throw the unchecked exception TestException.

  3. Line 45 can throw the unchecked exception TestException.

  4. Line 46 will compile if the enclosing method throws a TestException.

  5. Line 46 will compile if enclosed in a try block, where TestException

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Correct Option: D,E

Given: public class NamedCounter { private final String name; private int count; public NamedCounter(String name) { this.name = name; } public String getName() { return name; } public void increment() { coount++; } public int getCount() { return count; } public void reset() { count = 0; } } Which three changes should be made to adapt this class to be used safely by multiple threads? (Choose three.)
technology programming languages

  1. declare reset() using the synchronized keyword

  2. declare getName() using the synchronized keyword

  3. declare getCount() using the synchronized keyword

  4. declare the constructor using the synchronized keyword

  5. declare increment() using the synchronized keyword

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Correct Option: A,C,E

Click the Exhibit button. 1. import java.util.*; 2. 3. public class NameList { 4. private List names = new ArrayList(); 5. public synchronized void add(String name) { names.add(name); } 6. public synchronized void printAll() { 7. for (int i = 0; i

technology programming languages

  1. An exception may be thrown at runtime.

  2. The code may run with no output, without exiting.

  3. The code may run with no output, exiting normally.

  4. The code may rum with output “A B A B C C “, then exit.

  5. The code may rum with output “A B C A B C A B C “, then exit.

  6. The code may ruin with output “A B C A A B C A B C “, then exit.

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Correct Option: E,F

Click the Exhibit button. 10. public class Transfers { 11. public static void main(String[] args) throws Exception { 12. Record r1 = new Record(); 13. Record r2 = new Record(); 14. doTransfer(r1, r2, 5); 15. doTransfer(r2, r1, 2); 16. doTransfer(r1, r2, 1); 17. // print the result 18. System.out.println(”rl = “ + r1.get() +“, r2=” + r2.get()); 19. } 20. private static void doTransfer( 21. final Record a, final Record b, final int amount) { 22. Thread t = new Thread() { 23. public void run() { 24. new Clerk().transfer(a, b, amount); 25. } 26. }; 27. t.start(); 28. } 29. } 30. class Clerk { 31. public synchronized void transfer(Record a, Record b, int amount){ 32. synchronized (a) { 33. synchronized (b) { 34. a.add(-amount); 35. b.add(amount); 36. } 37. } 38. } 39. } 40. class Record { 41.int num=10; 42. public int get() { return num; } 43. public void add(int n) { num = num + n; } 44. } If Transfers.main() is run, which three are true? (Choose three.)

technology programming languages

  1. The output may be “r1 = 6, r2 = 14”.

  2. The output may be “r1 = 5, r2 = 15”.

  3. The output may be “r1 = 8, r2 = 12”.

  4. The code may run (and complete) with no output.

  5. The code may deadlock (without completing) with no output.

  6. M IllegalStateException or InterruptedException may be thrown at

Show answer
Correct Option: A,B,E

AI Explanation

To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) The output may be "r1 = 6, r2 = 14" - This option is true. In the given code, the doTransfer method is called three times, each time transferring a certain amount from one Record object to another. As the transfer method in the Clerk class is synchronized, only one thread can execute the transfer at a time. In the first transfer (doTransfer(r1, r2, 5)), the value of r1 is decreased by 5 and the value of r2 is increased by 5. Therefore, after the first transfer, the value of r1 will be 5 and the value of r2 will be 15. In the subsequent transfers, the values will be updated accordingly, resulting in "r1 = 6, r2 = 14" as a possible output.

Option B) The output may be "r1 = 5, r2 = 15" - This option is true. As explained in option A, after the first transfer, the value of r1 will be 5 and the value of r2 will be 15. Therefore, "r1 = 5, r2 = 15" is a possible output.

Option C) The output may be "r1 = 8, r2 = 12" - This option is false. The given code does not involve any transfers or operations that would result in r1 becoming 8 and r2 becoming 12.

Option D) The code may run (and complete) with no output - This option is true. The code may execute without any errors and complete without printing any output.

Option E) The code may deadlock (without completing) with no output - This option is true. Deadlock can occur in a multi-threaded program when two or more threads are waiting for each other to release a resource. In this code, there are multiple synchronized blocks and multiple threads running concurrently. If a deadlock occurs, the code may get stuck and not complete, resulting in no output.

Option F) IllegalStateException or InterruptedException may be thrown - This option is false. There are no specific conditions in the given code that would cause an IllegalStateException or InterruptedException to be thrown.

Therefore, the correct answers are A, B, and E.

Given: 11. class ClassA {} 12. class ClassB extends ClassA {} 13. class ClassC extends ClassA {} and: 21. ClassA p0 = new ClassA(); 22. ClassB p1 = new ClassB(); 23. ClassC p2 = new ClassC(); 24. ClassA p3 = new ClassB(); 25. ClassA p4 = new ClassC(); Which three are valid? (Choose three.)
technology programming languages

  1. p0 = p1;

  2. p1 =p2;

  3. p2 = p4;

  4. p2 = (ClassC)p1;

  5. p1 = (ClassB)p3;

  6. p2 = (ClassC)p4;

Show answer
Correct Option: A,E,F

Given: 10. abstract class A { 11. abstract void al(); 12. void a2() { } 13. } 14. class B extends A { 15. void a1() { } 16. void a2() { } 17. } 18. class C extends B { void c1() { } } and: A x = new B(); C y = new C(); A z = new C(); Which four are valid examples of polymorphic method calls? (Choose four.)
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  1. x.a2();

  2. z.a2();

  3. z.c1();

  4. z.a1();

  5. y.c1();

  6. x.a1();

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Correct Option: A,B,D,F

Click the Exhibit button. 1. public class Car { 2. private int wheelCount; 3. private String vin; 4. public Car(String vin) { 5. this.vin = vin; 6. this.wheelCount = 4; 7. } 8. public String drive() { 9. return “zoom-zoom”; 10. } 11. public String getInfo() { 12. return “VIN: “+ vin + “wheels: “+ wheelCount; 13. } 14. } And: 1. public class MeGo extends Car { 2. public MeGo(String vin) { 3. this.wheelCount = 3; 4. } 5. } What two must the programmer do to correct the compilation errors? (Choose two.)
technology programming languages

  1. insert a call to this() in the Car constructor

  2. insert a call to this() in the MeGo constructor

  3. insert a call to super() in the MeGo constructor

  4. insert a call to super(vin) in the MeGo constructor

  5. change the wheelCount variable in Car to protected

  6. change line 3 in the MeGo class to super.wheelCount = 3;

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Correct Option: D,E

Given: 1. public class Blip { 2. protected int blipvert(int x) { return 0; } 3. } 4. class Vert extends Blip { 5. // insert code here 6. } Which five methods, inserted independently at line 5, will compile? (Choose five.)
technology programming languages

  1. public int blipvert(int x) { return 0; }

  2. protected long blipvert(int x, int y) { return 0; }

  3. private int blipvert(long x) { return 0; }

  4. protected long blipvert(int x) { return 0; }

  5. protected int blipvert(long x) { return 0; }

  6. protected long blipvert(long x) { return 0; }

Show answer
Correct Option: A,B,C,E,F