Java Programming - Objects and Collections MCQs Part 2

1. 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?

A.
TreeMap
B.
HashMap
C.
LinkedHashMap
D.
The answer depends on the implementation of the existing instance.

 Answer Option C

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

A.
java.lang.String
B.
java.lang.Double
C.
java.lang.StringBuffer
D.
java.lang.Character

 Answer Option C

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?

A.
java.util.HashSet
B.
java.util.LinkedHashSet
C.
java.util.List
D.
java.util.ArrayList

 Answer Option D

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?

A.
java.util.Map
B.
java.util.Set
C.
java.util.List
D.
java.util.Collection

 Answer Option B

5. Which interface does java.util.Hashtable implement?

A.
Java.util.Map
B.
Java.util.List
C.
Java.util.HashTable
D.
Java.util.Collection

 Answer Option A

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

A. Java.util.Map
B. Java.util.Set
C. Java.util.List
D. Java.util.Collection

 Answer Option A

7. 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?

A. java.util.ArrayList
B. java.util.LinkedHashMap
C. java.util.HashMap
D. java.util.TreeMap

 Answer Option B

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

A. java.util.SortedMap
B. java.util.TreeMap
C. java.util.TreeSet
D. java.util.Hashtable

 Answer Option D

9. Which is valid declaration of a float?

A. float f = 1F;
B. float f = 1.0;
C. float f = "1";
D. float f = 1.0d;

 Answer Option A

10. /* Missing Statement ? */
public class foo
{
public static void main(String[]args)throws Exception
{
java.io.PrintWriter out = new java.io.PrintWriter();
new java.io.OutputStreamWriter(System.out,true);
out.println("Hello");
}
}

What line of code should replace the missing statement to make this program compile?

A. No statement required.
B. import java.io.*;
C. include java.io.*;
D. import java.io.PrintWriter;

 Answer Option A

11. What is the numerical range of char?

A. 0 to 32767
B. 0 to 65535
C. -256 to 255
D. -32768 to 32767

 Answer Option B

12. Which of the following are Java reserved words?

run
import
default
implement

A. 1 and 2
B. 2 and 3
C. 3 and 4
D. 2 and 4

 Answer Option B

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

A. Java.util.Map
B. Java.util.Set
C. Java.util.List
D. Java.util.Collection

 Answer Option A

7. 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?

A. java.util.ArrayList
B. java.util.LinkedHashMap
C. java.util.HashMap
D. java.util.TreeMap

 Answer Option B

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

A. java.util.SortedMap
B. java.util.TreeMap
C. java.util.TreeSet
D. java.util.Hashtable

 Answer Option D

9. Which is valid declaration of a float?

A. float f = 1F;
B. float f = 1.0;
C. float f = "1";
D. float f = 1.0d;

 Answer Option A

10. /* Missing Statement ? */
public class foo
{
public static void main(String[]args)throws Exception
{
java.io.PrintWriter out = new java.io.PrintWriter();
new java.io.OutputStreamWriter(System.out,true);
out.println("Hello");
}
}

What line of code should replace the missing statement to make this program compile?

A. No statement required.
B. import java.io.*;
C. include java.io.*;
D. import java.io.PrintWriter;

 Answer Option A

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