This set of Java Multiple Choice Questions & Answers (MCQs) on “Java.lang – Byte & Short Wrappers”.
1. Which of these methods of Byte wrapper can be used to obtain Byte object from a string? Answer: c 2. Which of the following methods Byte wrapper return the value as a double? Answer: a 3. Which of these is a super class of wrappers Byte and short wrappers? Answer: d 4. Which of these methods is not defined in both Byte and Short wrappers? Answer: b 5. What will be the output of the following Java code? a) 0 6. What will be the output of the following Java program? a) 0 7. What will be the output of the following Java program? a) 0
a) toString()
b) getString()
c) decode()
d) encode()
Clarification: decode() methods returns a Byte object that contains the value specified by string.
a) doubleValue()
b) converDouble()
c) getDouble()
d) getDoubleValue()
Clarification: doubleValue() returns the value of invoking object as double.
a) Long
b) Digits
c) Float
d) Number
Clarification: Number is an abstract class containing subclasses Double, Float, Byte, Short, Integer and Long.
a) intValue()
b) isInfinite()
c) toString()
d) hashCode()
Clarification: isInfinite() methods is defined in Integer and Long Wrappers, returns true if specified value is an infinite value otherwise it returns false.
class Output
{
public static void main(String args[])
{
Double i = new Double(257.5);
Double x = i.MAX_VALUE;
System.out.print(x);
}
}
b) 1.7976931348623157E308
c) 1.7976931348623157E30
d) None of the mentioned
Clarification: 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
class Output
{
public static void main(String args[])
{
Double i = new Double(257.5);
Double x = i.MIN_VALUE;
System.out.print(x);
}
}
b) 4.9E-324
c) 1.7976931348623157E308
d) None of the mentioned
Clarification: 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
class Output
{
public static void main(String args[])
{
Double i = new Double(257.578123456789);
float x = i.floatValue();
System.out.print(x);
}
}
b) 257.0
c) 257.57812
d) 257.578123456789
Clarification: 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