Tag: programming languages

Questions Related to programming languages

Given: class CardBoard { Short story = 5; CardBoard go(CardBoard cb) { cb = null; return cb; } public static void main(String[] args) { CardBoard c1 = new CardBoard(); CardBoard c2 = new CardBoard(); CardBoard c3 = c1.go(c2); c1 = null; // do Stuff } } When // doStuff is reached, how many objects are eligible for GC?
technology programming languages

  1. 0

  2. 1

  3. 2

  4. Compilation fails

  5. It is not possible to know

  6. An exception is thrown at runtime

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Correct Option: C

Given: class Alien { String invade(short ships) { return "a few"; } String invade(short... ships) { return "many"; } } class Defender { public static void main(String [] args) { System.out.println(new Alien().invade(7)); } } What is the result?
technology programming languages

  1. many

  2. a few

  3. Compilation fails

  4. The output is not predictable

  5. An exception is thrown at runtime

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Correct Option: C

Given: 1. class Dims { 2. public static void main(String[] args) { 3. int[] [] a = {{1,2,}, {3,4}}; 4. int[] b = (int []) a [1] ; 5. Object o1 = a; 6. int[] [] a2 = (int[] []) o1; 7. int[] b2 = (int []) o1; 8. System.out.println(b[1]); 9. } } What is the result?
technology programming languages

  1. 2

  2. 4

  3. An exception is thrown at runtime

  4. Compilation fails due to an error on line 4

  5. Compilation fails due to an error on line 5

  6. Compilation fails due to an error on line 6

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Correct Option: C

Given: class Eggs { int doX(Long x, Long y) { return 1; } int doX(long... x) { return 2; } int doX(Integer x, Integer y) { return 3; } int doX(Number n, Number m) { return 4; } public static void main(String[] args) { new Eggs().go(); } void go () { short s = 7; System.out.print(doX(s,s) + " "); System.out.println(doX(7,7)); } }
technology programming languages

  1. 1 1

  2. 2 1

  3. 3 1

  4. 4 1

  5. 3 3

  6. 4 3

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Correct Option: C

Which is true? (Choose all that apply.)
technology programming languages

  1. The invocation of an object's finalize() method is always the last thing that happens before an object is garbage collected (GCed).

  2. When a stack variable goes out of scope it is eligible for GC.

  3. Some reference variables live on the stack, and some live on the heap.

  4. Only objects that have no reference variables referring to them can be eligible for GC.

  5. It's possible to request the GC via methods in either java. lang. Runtime or java.lang.System classes.

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Correct Option: C,E

Given: 1. class Convert { 2. public static void main(String[] args) { 3. Long xL = new Long(456L); 4. long x1 = Long.valueOf("123"); 5. Long x2 = Long.valueOf("123"); 6. long x3 = xL.longValue(); 7. Long x4 = xL.longValue(); 8. Long x5 = Long.parseLong("456"); 9. long x6 = Long.parseLong("123"); 10. } 11. } Which will compile using Java 5, but will NOT compile using Java 1.4? (Choose all that apply.)

technology programming languages

  1. Line 4

  2. Line 5

  3. Line 6

  4. Line 7

  5. Line 8

  6. Line 9

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Correct Option: A,D,E

Given: 1. class Bigger { 2. public static void main(String[] args) { 3. // insert code here 4. } 5. } 6. class Better { 7. enum Faster {Higher, Longer}; 8. } Which, inserted independently at line 3, will compile? (Choose all that apply.)
technology programming languages

  1. Faster f = Faster.Higher;

  2. Faster f = Better.Faster.Higher;

  3. Better.Faster f = Better.Faster.Higher;

  4. Bigger.Faster f = Bigger.Faster.Higher;

  5. Better. Faster f2; f2 = Better.Faster.Longer;

  6. Better b; b.Faster = f3; f3 = Better.Faster.Longer;

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Correct Option: C,E

Given: 1. class Example { 2. public static void main(String[] args) { 3. Short s = 15; 4. Boolean b; 5. // insert code here 6. } 7. } Which, inserted independently at line 5, will compile? (Choose all that apply.)
technology programming languages

  1. b = (Number instanceof s);

  2. b = (s instanceof Short);

  3. b = s.instanceof(Short);

  4. b = (s instanceof Number);

  5. b = s.instanceof(Object);

  6. b = (s instanceof String);

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Correct Option: B,D

Given two files: 1. class One { 2. public static void main(String[] args) { 3. int assert = 0; 4. } 5. } 1. class Two { 2. public static void main(String[] args) { 3. assert(false); 4. } 5. } And the four command-line invocations: javac -source 1.3 One.java javac -source 1.4 One.java javac -source 1.3 Two.java javac -source 1.4 Two.java What is the result? (Choose all that apply.)
technology programming languages

  1. Only one compilation will succeed.

  2. Exactly two compilations will succeed.

  3. Exactly three compilations will succeed.

  4. All four compilations will succeed.

  5. No compiler warnings will be produced.

  6. At least one compiler warning will be produced.

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Correct Option: B,F

Given: class Mixer { Mixer() { } Mixer(Mixer m) { ml = m;} Mixer m1; public static void main(String[] args) { Mixer m2 = new Mixer(); Mixer m3 = new Mixer(m2); m3.go(); Mixer m4 = m3.m1; m4.go(); Mixer m5 = m2.m1; m5.go(); } void go() { System.out.print("hi "); } } What is the result?
technology programming languages

  1. hi

  2. hi hi

  3. hi hi hi

  4. Compilation fails

  5. hi, followed by an exception

  6. hi hi, followed by an exception

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Correct Option: F