java-Collections(part-II)-vlits

Which of the following are true statements?

1.The Iterator interface declares only three methods: hasNext, next and remove. 2.The ListIterator interface extends both the List and Iterator interfaces.

3.The ListIterator interface provides forward and backward iteration capabilities.

4.The ListIterator interface provides the ability to modify the List during iteration.

5.The ListIterator interface provides the ability to determine its position in the List.

• 2, 3, 4 and 5

• 1, 3, 4 and 5

• 3, 4 and 5

• 1, 2 and 3

Which collection class allows you to associate its elements with key values, and allows you to retrieve objects in FIFO (first-in, first-out) sequence?

• java.util.ArrayList

• java.util.LinkedHashMap

• java.util.HashMap

• java.util.TreeMap

What will be the output of the program?

TreeSet map = new TreeSet();

map.add("one");

map.add("two");

map.add("three");

map.add("four");

map.add("one");

Iterator it = map.iterator();

while (it.hasNext() )

{

System.out.print( it.next() + " " );

}

• one two three four

• four three two one

• four one three two

• one two three four one

Which statement is true for the class java.util.ArrayList?

• The elements in the collection are ordered.

• The collection is guaranteed to be immutable.

• The elements in the collection are guaranteed to be unique.

• The elements in the collection are accessed using a unique key.

Which collection class allows you to access its elements by associating a key with an element's value, and provides synchronization?

• java.util.SortedMap

• java.util.TreeMap

• java.util.TreeSet

• java.util.Hashtable

What will be the output of the program?

public static void main(String[] args)

{

Object obj = new Object()

{

public int hashCode()

{

return 42;

}

};

System.out.println(obj.hashCode());

}

• 42

• Runtime Exception

• Compile Error at line 2

• Compile Error at line 5

Which of these is not a interface in the Collections Framework?

• Collection

• Group

• set

• List

Which interface restricts duplicate elements?

• set

• list

• Map

• All of these

Which of these collection class has the ability to grow dynamically?

• Array

• Arrays

• ArrayList

• None of these

The accuracy and efficiency of a HashMap can be guaranteed with:

• override equals method

• override hashCode method

• (All of these)