Java Questions & Answers – Java.lang – Byte & Short Wrappers

This section of our 1000+ Java MCQs focuses on Double and Float wrappers of Java Programming Language.

1. Which of these methods of Byte wrapper can be used to obtain Byte object from a string?
a) toString()
b) getString()
c) decode()
d) encode()
View Answer

Answer: c
Explanation: decode() methods returns a Byte object that contains the value specified by string.

2. Which of the following methods Byte wrapper return the value as a double?
a) doubleValue()
b) converDouble()
c) getDouble()
d) getDoubleValue()
View Answer

Answer: a
Explanation: doubleValue() returns the value of invoking object as double.

3. Which of these is a super class of wrappers Byte and short wrappers?
a) Long
b) Digits
c) Float
d) Number
View Answer

Answer: d
Explanation: Number is an abstract class containing subclasses Double, Float, Byte, Short, Integer and Long.

4. Which of these methods is not defined in both Byte and Short wrappers?
a) intValue()
b) isInfinite()
c) toString()
d) hashCode()
View Answer

Answer: b
Explanation: isInfinite() methods is defined in Integer and Long Wrappers, returns true if specified value is an infinite value otherwise it returns false.

5. Which of these exceptions is thrown by compareTo() method defined in double wrapper?
a) IOException
b) SystemException
c) CastException
d) ClassCastException
View Answer

Answer: d
Explanation: compareTo() methods compare the specified object to be double, if it is not then ClassCastException is thrown.

6. What is the output of this program?

  1.     class Output {
  2.         public static void main(String args[]) {
  3.             Double i = new Double(257.5);  
  4.             Double x = i.MAX_VALUE;
  5.             System.out.print(x);
  6.         }
  7.     }

a) 0
b) 1.7976931348623157E308
c) 1.7976931348623157E30
d) None of the mentioned
View Answer

Answer: b
Explanation: The super class of Double class defines a constant MAX_VALUE above which a number is considered to be infinity. MAX_VALUE is 1.7976931348623157E308.
Output:
$ javac Output.java
$ java Output
1.7976931348623157E308

7. What is the output of this program?

  1.     class Output {
  2.         public static void main(String args[]) {
  3.             Double i = new Double(257.5);  
  4.             Double x = i.MIN_VALUE;
  5.             System.out.print(x);
  6.         }
  7.     }

a) 0
b) 4.9E-324
c) 1.7976931348623157E308
d) None of the mentioned
View Answer

Answer: b
Explanation: The super class of Byte class defines a constant MIN_VALUE below which a number is considered to be negative infinity. MIN_VALUE is 4.9E-324.
Output:
$ javac Output.java
$ java Output
4.9E-324

8. What is the output of this program?

  1.     class Output {
  2.          public static void main(String args[]) {
  3.              Integer i = new Integer(257);  
  4.              byte x = i.byteValue();
  5.              System.out.print(x);
  6.         }
  7.     }

a) 0
b) 1
c) 256
d) 257
View Answer

Answer: b
Explanation: i.byteValue() method returns the value of wrapper i as a byte value. i is 257, range of byte is 256 therefore i value exceeds byte range by 1 hence 1 is returned and stored in x.
Output:
$ javac Output.java
$ java Output
1

9. What is the output of this program?

  1.     class Output {
  2.         public static void main(String args[]) {
  3. 	    Double i = new Double(257.578123456789);  
  4.             float x = i.floatValue();
  5.             System.out.print(x);
  6.         }
  7.     }

a) 0
b) 257.0
c) 257.57812
d) 257.578123456789
View Answer

Answer: c
Explanation: floatValue() converts the value of wrapper i into float, since float can measure till 5 places after decimal hence 257.57812 is stored in floating point variable x.
Output:
$ javac Output.java
$ java Output
257.57812

10. What is the output of this program?

  1.     class Output {
  2.         public static void main(String args[]) {
  3.             Double y = new Double(257.57812);
  4. 	    Double i = new Double(257.578123456789);  
  5.             try {
  6. 	        int x = i.compareTo(y);
  7.                 System.out.print(x);
  8.             }
  9.             catch(ClassCastException e) {
  10.                 System.out.print("Exception");
  11.             }
  12. 	}
  13.     }

a) 0
b) 1
c) Exception
d) None of the mentioned
View Answer

Answer: b
Explanation: i.compareTo() methods two double values, if they are equal then 0 is returned and if not equal then 1 is returned, here 257.57812 and 257.578123456789 are not equal hence 1 is returned and stored in x.
Output:
$ javac Output.java
$ java Output
1

Sanfoundry Global Education & Learning Series – Java Programming Language.

About

Manish Bhojasia, a technology veteran with 17+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer and SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage & Cluster Administration, Advanced C Programming, SAN Storage Technologies, SCSI Internals and Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him below.


Sanfoundry Training Center of Excellence (CoE)

Manish Bhojasia, a technology veteran with 17+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer and SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage & Cluster Administration, Advanced C Programming, SAN Storage Technologies, SCSI Internals and Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him below.







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