• II only

• I and II

• None

• I only

• In Java, which of the following is (are) true of both arrays and ArrayList objects?

• Both use the bracket operator and an index to access individual elements.

• Both are resizable.

• Elements are inserted into both with the method add.

• I only

• II only

• III only

• None

• What will be output when the following Java program segment is executed?

ArrayList<String> animals = new ArrayList<String>();

animals.add("cat");

animals.add("dog");

for (Iterator<String> i = animals.iterator(); i.hasNext(); ) {

System.out.print(i.next().charAt(0));

}

• catdog

• c

• ca

• cd

• What will be output when the following Java program segment is executed?

ArrayList<String> animals = new ArrayList<String>();

animals.add("cat");

animals.add("dog");

animals.add("dog");

for (int i = 0; i < animals.size(); ++i) {

if (animals.get(i).equals("dog")) {

animals.remove(i);

}

}

System.out.println(animals.size());

• 3

• 0

• 1

• 2

• What will be output when the following Java program segment is executed?

String[] strings = {"bird", "dog"};

for (int i = strings.length - 1; i >= 0; --i) {

System.out.print(strings[i].length() + " ");

}

• bird dog

• dog bird

• 4 3

• 3 4

• In Java, an individual component of an array can be accessed using an index and which of the following operators?

  • ( )

  • .

  • instanceof

  • [ ]

• Consider the following Java code segment.

int[] foo = new int[5];

At the end of execution of the segment, what will be the value of foo[2]?

• 2

• 3

• null

• 0

• A reference variable r in Java can hold a reference to which of the following?

• An object having the same declared type as r

• An object of any subclass of the declared type of r

• An object of any superclass of the declared type of r

• I, II, and III only

• I only

• I and III only

• I and II only

• Consider the following Java program segment.

class Aircraft {

void takeOff() {...}

}

class Helicopter extends Aircraft {

void takeOff() {...}

}

...

Helicopter h = new Helicopter();

Aircraft a = new Aircraft();

Aircraft ah = new Helicopter();

Execution of which of the following lines would cause the method takeoff of the class Helicopter to be executed?

• h.takeOff();

• a.takeOff();

• ah.takeoff();

• I, II, and III

• I only

• I and II only

• I and III only

• In Java, which of the following can appear in abstract classes but not in interfaces?

• Definitions of instance variables

• Implementation of methods

• Implementation of constructors

• I only

• I and II only

• II and III only

• I, II, and III

• In Java, which of the following is (are) true regarding interfaces?

• An interface can extend a class.

• An interface can extend multiple interfaces.

• I only

• I and II

• None

• II only

• A singleton class typically refers to its instance via a _____ variable.

  • public static

  • private instance

  • public instance

  • private static

• In singleton classes, the constructor is _____ to ensure that instantiation is controlled through a(n) _____ method.

  • private, instance

  • omitted, static

  • omitted, instance

  • private, static

• Which of the following is (are) true regarding the strategy design pattern?

• A family of algorithms are combined into a large single method.

• Polymorphism is used.