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Java Objects and Collections Quiz

Description: Java Objects and Collections Quiz
Number of Questions: 10
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Tags: java

Suppose that you would like to create an instance of a new Map that has an iteration order that is the same as the iteration order of an existing instance of a Map. Which concrete implementation of the Map interface should be used for the new instance?

  1. TreeMap

  2. HashMap

  3. LinkedHashMap

  4. The answer depends on the implementation of the existing instance.

Answer: 3

Which class does not override the equals() and hashCode() methods, inheriting them directly from class Object?

  1. java.lang.String

  2. java.lang.Double

  3. java.lang.StringBuffer

  4. java.lang.Character

Answer: 3

Which collection class allows you to grow or shrink its size and provides indexed access to its elements, but whose methods are not synchronized?

  1. java.util.HashSet

  2. java.util.LinkedHashSet

  3. java.util.List

  4. java.util.ArrayList

Answer: 4

You need to store elements in a collection that guarantees that no duplicates are stored and all elements can be accessed in natural order. Which interface provides that capability?

  1. java.util.Map

  2. java.util.Set

  3. java.util.List

  4. java.util.Collection

Answer: 2

Which interface does java.util.Hashtable implement?

  1. Java.util.Map

  2. Java.util.List

  3. Java.util.HashTable

  4. Java.util.Collection

Answer: 1
Explanation:

Hash table based implementation of the Map interface.

Which interface provides the capability to store objects using a key-value pair?

  1. Java.util.Map

  2. Java.util.Set

  3. Java.util.List

  4. Java.util.Collection

Answer: 1
Explanation:

An object that maps keys to values. A map cannot contain duplicate keys; each key can map to at most one value.

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?

  1. java.util.ArrayList

  2. java.util.LinkedHashMap

  3. java.util.HashMap

  4. java.util.TreeMap

Answer: 2

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

  1. java.util.SortedMap

  2. java.util.TreeMap

  3. java.util.TreeSet

  4. java.util.Hashtable

Answer: 4

Which is valid declaration of a float?

  1. float f = 1F;

  2. float f = 1.0;

  3. float f = "1";

  4. float f = 1.0d;

Answer: 1

What is the numerical range of char?

  1. 0 to 32767

  2. 0 to 65535

  3. -256 to 255

  4. -32768 to 32767

Answer: 2
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