INTERVIEW QUESTIONS (JAVA) Prepared by SRINUVASARAO DESETTI 1. What is the most important feature of Java? Java is a platform independent language. 2. What do you mean by platform independence? Platform independence means that we can write and compile the java code in one platform (eg Windows) and can execute the class in any other supported platform eg (Linux,Solaris,etc). 3. What is a JVM? JVM is Java Virtual Machine which is a run time environment for the compiled java class files. 4. Are JVM's platform independent? JVM's are not platform independent. JVM's are platform specific run time implementation provided by the vendor. 5. What is the difference between a JDK and a JVM? JDK is Java Development Kit which is for development purpose and it includes execution environment also. But JVM is purely a run time environment and hence you will not be able to compile your source files using a JVM. 6. What is a pointer and does Java support pointers? Pointer is a reference handle to a memory location. Improper handling of pointers leads to memory leaks and reliability issues hence Java doesn't support the usage of pointers.
Important Questions-When you are facing interview on CORE JAVA
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INTERVIEW QUESTIONS (JAVA) Prepared by SRINUVASARAO DESETTI1.
What is the !st ip!rta"t #eat$re !# Ja%a&Ja%a is a p'at#!r
i"depe"de"t 'a"($a(e.). What d! y!$ ea" by p'at#!r
i"depe"de"*e&P'at#!r i"depe"de"*e ea"s that +e *a" +rite a"d
*!pi'e the ,a%a *!de i" !"e p'at#!r (e( Wi"d!+s) a"d *a" e-e*$te
the *'ass i" a"y !ther s$pp!rted p'at#!r e( (.i"$-/S!'aris/et*).0.
What is a JV1&JV1 is Ja%a Virt$a' 1a*hi"e +hi*h is a r$" tie
e"%ir!"e"t #!r the *!pi'ed ,a%a *'ass #i'es.2. Are JV13s p'at#!r
i"depe"de"t&JV13s are "!t p'at#!r i"depe"de"t. JV13s are
p'at#!r spe*i#i* r$" tie ip'ee"tati!" pr!%ided by the %e"d!r.4.
What is the di##ere"*e bet+ee" a JD5 a"d a JV1&JD5 is Ja%a
De%e'!pe"t 5it +hi*h is #!r de%e'!pe"t p$rp!se a"d it i"*'$des
e-e*$ti!" e"%ir!"e"t a's!. 6$t JV1 is p$re'y a r$" tie e"%ir!"e"t
a"d he"*e y!$ +i'' "!t be ab'e t! *!pi'e y!$r s!$r*e #i'es $si"( a
JV1.7. What is a p!i"ter a"d d!es Ja%a s$pp!rt p!i"ters&P!i"ter
is a re#ere"*e ha"d'e t! a e!ry '!*ati!". Ipr!per ha"d'i"( !#
p!i"ters 'eads t! e!ry 'ea8s a"d re'iabi'ity iss$es he"*e Ja%a
d!es"3t s$pp!rt the $sa(e !# p!i"ters.9. What is the base *'ass !#
a'' *'asses&java.lang.Object:. D!es Ja%a s$pp!rt $'tip'e
i"herita"*e&Ja%a d!es"3t s$pp!rt $'tip'e i"herita"*e.;. Is Ja%a
a p$re !b,e*t !rie"ted 'a"($a(e&Ja%a $ses priiti%e data types
a"d he"*e is "!t a p$re !b,e*t !rie"ted 'a"($a(e.1ed t! their
de#a$'t %a'$es.12. ?!+ t! de#i"e a *!"sta"t %ariab'e i"
Ja%a&The %ariab'e sh!$'d be de*'ared as static a"d final. S!
!"'y !"e *!py !# the %ariab'e e-ists #!r a'' i"sta"*es !# the *'ass
a"d the %a'$e *a"3t be *ha"(ed a's!.static final int PI = 2.14; is
a" e-ap'e #!r *!"sta"t.14. Sh!$'d a ai"() eth!d be *!p$'s!ri'y
de*'ared i" a'' ,a%a *'asses&N! "!t re@$ired. main() eth!d
sh!$'d be de#i"ed !"'y i# the s!$r*e *'ass is a ,a%a
app'i*ati!".17. What is the ret$r" type !# the ai"()
eth!d&Main() eth!d d!es"3t ret$r" a"ythi"( he"*e de*'ared
void.19. Why is the ai"() eth!d de*'ared stati*&main() eth!d is
*a''ed by the JV1 e%e" be#!re the i"sta"tiati!" !# the *'ass he"*e
it is de*'ared as static.1:. What is the ar($ee"t !# ai"()
eth!d&main() eth!d a**epts a" array !# Stri"( !b,e*t as
ar($ee"t.1;. =a" a ai"() eth!d be !%er'!aded&Aes. A!$ *a" ha%e
a"y "$ber !# main() eth!ds +ith di##ere"t eth!d si("at$re a"d
ip'ee"tati!" i" the *'ass.) &It is +ritte" ) . - / %.::. ?!+ is
r!$"di"( per#!red $"der i"te(er di%isi!"&The #ra*ti!"a' part !#
the res$'t is tr$"*ated. This is 8"!+" as r!$"di"( t!+ard
>er!.:;. I# a *'ass is de*'ared +ith!$t a"y a**ess !di#iers/
+here ay the *'ass be a**essed&A *'ass that is de*'ared +ith!$t
a"y a**ess !di#iers is said t! ha%e pa*8a(e a**ess. This ea"s that
the *'ass *a" !"'y be a**essed by !ther *'asses a"d i"ter#a*es that
are de#i"ed +ithi" the sae pa*8a(e.;ers *a" y!$ ha%e &As a"y as
y!$ +a"t/ b$t the stati* i"itia'i>ers a"d *'ass %ariab'e
i"itia'i>ers are e-e*$ted i" te-t$a' !rder a"d ay "!t re#er t!
*'ass %ariab'es de*'ared i" the *'ass +h!se de*'arati!"s appear
te-t$a''y a#ter the $se/ e%e" th!$(h these *'ass %ariab'es are i"
s*!pe.112. What is the di##ere"*e bet+ee" eth!d !%erridi"( a"d
!%er'!adi"(&O%erridi"( is a eth!d +ith the sae "ae a"d ar($e"ts
as i" a pare"t/ +hereas !%er'!adi"( isthe sae eth!d "ae b$t
di##ere"t ar($e"ts114. What is *!"str$*t!r *hai"i"( a"d h!+ is it
a*hie%ed i" Ja%a &A *hi'd !b,e*t *!"str$*t!r a'+ays #irst "eeds
t! *!"str$*t its pare"t (+hi*h i" t$r" *a''s its pare"t
*!"str$*t!r.). I" Ja%a it is d!"e %ia a" ip'i*it *a'' t! the
"!Bar(s *!"str$*t!r as the #irst statee"t.117. What is the
di##ere"*e bet+ee" the 6!!'ea" I !perat!r a"d the II
!perat!r&I# a" e-pressi!" i"%!'%i"( the 6!!'ea" I !perat!r is
e%a'$ated/ b!th !pera"ds are e%a'$ated. The" the I !perat!r is
app'ied t! the !pera"d. Whe" a" e-pressi!" i"%!'%i"( the II
!perat!r is e%a'$ated/ the #irst !pera"d is e%a'$ated. I# the #irst
!pera"d ret$r"s a %a'$e !# tr$e the" the se*!"d !pera"d is
e%a'$ated. The II !perat!r is the" app'ied t! the #irst a"d se*!"d
!pera"ds. I#the #irst !pera"d e%a'$ates t! #a'se/ the e%a'$ati!" !#
the se*!"d !pera"d is s8ipped.119. Whi*h Ja%a !perat!r is ri(ht
ass!*iati%e&The J !perat!r is ri(ht ass!*iati%e.11:. =a" a
d!$b'e %a'$e be *ast t! a byte&Aes/ a d!$b'e %a'$e *a" be *ast
t! a byte.11;. What is the di##ere"*e bet+ee" a brea8 statee"t a"d
a *!"ti"$e statee"t&A b!ea statee"t res$'ts i" the teri"ati!"
!# the statee"t t! +hi*h it app'ies (s+it*h/ #!r/ d!/ !r +hi'e). A
continue statee"t is $sed t! e"d the *$rre"t '!!p iterati!" a"d
ret$r" *!"tr!' t! the '!!p statee"t.1)ed&The de#a$'t %a'$e !#
a" Stri"( type is "$''.1)). What is the di##ere"*e bet+ee" a #ie'd
%ariab'e a"d a '!*a' %ariab'e&A #ie'd %ariab'e is a %ariab'e
that is de*'ared as a eber !# a *'ass. A '!*a' %ariab'e is a
%ariab'e that is de*'ared '!*a' t! a eth!d.1)0. ?!+ are this() a"d
s$per() $sed +ith *!"str$*t!rs&t$is() is $sed t! i"%!8e a
*!"str$*t!r !# the sae *'ass. supe!() is $sed t! i"%!8e a
s$per*'ass *!"str$*t!r.1)2. What d!es it ea" that a *'ass !r eber
is #i"a'&A #i"a' *'ass *a""!t be i"herited. A #i"a' eth!d
*a""!t be !%erridde" i" a s$b*'ass. A #i"a' #ie'd *a""!t be *ha"(ed
a#ter it3s i"itia'i>ed/ a"d it $st i"*'$de a" i"itia'i>er
statee"t +here it3s de*'ared.1)4. What d!es it ea" that a eth!d !r
*'ass is abstra*t&A" abstra*t *'ass *a""!t be i"sta"tiated.
Abstra*t eth!ds ay !"'y be i"*'$ded i" abstra*t *'asses. ?!+e%er/
a" abstra*t *'ass is "!t re@$ired t! ha%e a"y abstra*t eth!ds/
th!$(h !st !# the d!. Ea*h s$b*'ass !# a" abstra*t *'ass $st
!%erride the abstra*t eth!ds !# its s$per*'asses!r it a's! sh!$'d
be de*'ared abstra*t.1)7. What is a tra"sie"t
%ariab'e&Tra"sie"t %ariab'e is a %ariab'e that ay "!t be
seria'i>ed.1)9. ?!+ d!es Ja%a ha"d'e i"te(er !%er#'!+s a"d
$"der#'!+s&It $ses th!se '!+ !rder bytes !# the res$'t that *a"
#it i"t! the si>e !# the type a''!+ed by the !perati!".1):. What
is the di##ere"*e bet+ee" the KK a"d KKK !perat!rs&The KK
!perat!r *arries the si(" bit +he" shi#ti"( ri(ht. The KKK
>er!B#i''s bits that ha%e bee" shi#ted !$t.1);. Is si>e!# a
8ey+!rd&The si>e!# !perat!r is "!t a 8ey+!rd.
