Java - Data Types - Interview Questions and Answers on Boolean / boolean

Q1.  Variable of the boolean type is automatically initialized as?

Ans. The default value of the boolean type is false.

Q2. What is the difference between boolean and Boolean ?

Ans. boolean is a promitive type whereas Boolean is a wrapper class.

Q3.  What are the Wrapper classes available for primitive types ?

Ans. boolean  - java.lang.Boolean

byte - java.lang.Byte

char - java.lang.Character

double - java.lang.Double

float - java.lang.Float

int - java.lang.Integer

long - java.lang.Long

short - java.lang.Short

void - java.lang.Void

Q4.  Which data types are supported by JSON ?

Ans. Number

String

Boolean

Array

Object

null

Q5.  What are the default or implicitly assigned values for data types in java ?

Ans. boolean ---> false

byte ----> 0

short ----> 0

int -----> 0

long ------> 0l

char -----> /u0000

float ------> 0.0f

double ----> 0.0d

any object reference ----> null

Q6. What is the use of Boolean method valueOf(String s) ?

Ans. This method returns the boolean value for the specified string. The returned value represents a true value if the string argument is not Null and is equal, ignoring case, to the string "true".