Basics

Question 1

What is Source code

Answer 1

Human Understandable code written using english

Question 2

Native code (or) binary code (or) Machine code

Answer 2

Machine Understandable code written using low level programming language

Question 3

Byte Code

Answer 3

Jvm understandable code generated by java compiler

Question 4

Low Level Programming Language

Answer 4

Written using binary digits

Question 5

Middle Level Programming Language

Answer 5

Written using assembly codes like add,sub,mul,div

Question 6

High Level Programming Language

Answer 6

written using english

Question 7

Compiler

Answer 7

compiler is a translator used to convert Source code to byte code

Question 8

JVM

Answer 8

used to convert byte code to machine code
provides runtime environment.Doesnot physically exist

Question 9

JRE

Answer 9

it is an implementation of Jvm.physically exist
JVM+class libraries

Question 10

JDK

Answer 10

contains JVM+JRE+java deveopment tools=>javadoc,jar

Question 11

JIT

Answer 11

Converts necessary part of byte code to machine code instead of line by line

Question 12

Difference between c++ and java

Answer 12

c++ supports pointers
java doesnt support pointers
c++ supports go to statement
java doesnot support go to statement
c++ supports multiple inheritance
java doesnot supports multiple inheritance
c++ is platform dependent
java is platform independent
c++ is use compiler only for compile and run the program

Question 13

Class Loader

Answer 13

Subsytem of jvm.whenerver java program is run it loaed by the classloader first

Question 14

default value of local variables

Answer 14

no default value.local variables should be initialized before use it

Question 15

access Modifiers

Answer 15

public=>can be access from anywhere
private=>can be access within the class
protected=>within the package and sub class of another package
default=>within the package

Question 16

can a class can be name only with .java

Answer 16

yes.it has to compile with javac.java
run with the class name

Question 17

Memory areas

Answer 17

class area:stores method codes and static methods
heap area:stores objects
stack area:stores local varaiables
program counter register:contains the addresses of current execution code
native area:contains native methods