Definitions

Question 1

Define Byte Code

Answer 1

The optimized instruction created by Java compiler from a java class. Carries a .class extension. Is sent to interpretation for native machine.

Question 2

Define JVM

Answer 2

Is a java system software that converts byte code to machine code depending upon the machine.

Question 3

Define JIT

Answer 3

Interprets the whole java byte code in one go to machine code. Makes the interpretation step faster. Interprets only the required byte code.

Question 4

Define Garbage Collector

Answer 4

Background memory management tool that handles clearing memory space by java program so that user does not have to.

Question 5

Define fundamental datatypes

Answer 5

supplied by language developers to define value storage, can’t store multiple values.

Question 6

Define derived data types

Answer 6

store multiple values. eg arrays

Question 7

Define User defined data types

Answer 7

combination of fundamental data types to store different types of data

Question 8

Define method overloading

Answer 8

Method name is same; but signature is different

Question 9

Define method overriding

Answer 9

Method name is same; but method body is different

Question 10

What is class loader sub system or Java ClassLoader

Answer 10

Part of java run time environment that loads class dynamically into JVM.

Question 11

Duplicate methods

Answer 11

Have same return type, and same signature.

Need not have same body.

Question 12

Wrapper class

Answer 12

classes that can wrap objects around primitive data types

Question 13

Constructor

Answer 13

special method that is automatically called for object creation by JVM. can be used to initialize member methods.

Question 14

Default Constructor

Answer 14

A constructor that has empty parameters.
Also known as system constructor.
Is provided by default to all classes in JVM.

Question 15

Object Parameterized Constructor

Answer 15

Copy Constructor.

Takes object of same type as parameter, copies corresponding values into new object.

Question 16

Overloaded/Parameterized Constructor

Answer 16

same name as constructor name, and different signature(no. of para/type of para/order of para – at least one is different)

Question 17

javap

Answer 17

command to list class profile(name, attributes, methods, and constructors).
To be used only after compilation of a program.

Question 18

Factory Method

Answer 18

a method that has same return type as class to which it belongs.

Question 19

Define Inheritance

Answer 19

the process of deriving data members and methods from one class into another

Question 20

base class

Answer 20

the class giving its members/methods to another class in inheritance also known as super/parent class.

Question 21

derived class

Answer 21

the class taking members/methods from another class in inheritance also known as child/sub class

Question 22

StackOverFlowError

Answer 22

when a method is called indefinitely, it fills up the stack memory, and causes this error.

Question 23

Polymorphism

Answer 23

one things takes on many different forms

Question 24

what does BLC stand for?

Answer 24

Business Logic Class

Question 25

static binding

Answer 25

type of polymorphism that happens during compile-time. the method to be resolved is decided at compile-time.

Question 26

dynamic binding

Answer 26

type of polymorphism that happens during runtime. the method to be executed can be resolved only during runtime when objects are known to JVM.

Question 27

abstract concrete class

Answer 27

a class that has only null body methods; it needs the abstract keyword.

Question 28

null block method

Answer 28

a method that is defined but has no statements.

Question 29

interface in java

Answer 29

collection of universal common reusable data members, and methods | collection of public static final data members and public abstract methods.

Question 30

functional interface

Answer 30

an interface having only one abstract method which is implemented in an anonymous inner class

Question 31

API

Answer 31

Application Programming Interface; collection of packages.

Question 32

package

Answer 32

collection of other packages, classes, and sub packages

Question 33

Access modifiers

Answer 33

show sharing privileges; applied to classes and interfaces

Question 34

Access specifiers

Answer 34

show sharing privileges; applied to data members and data methods

Question 35

Exception

Answer 35

a run time error that occurs in java program

Question 36

checked exceptions

Answer 36

direct subclasses of java.lang.Exception these are caught by the compiler at compile time itself even before they get into runtime;

example: FileNotFound, Interrupted, IOException, ClassNotFound

Question 37

un-checked exceptions

Answer 37

direct subclasses of java.lang.RuntimeException these are caught only at runtime

Question 38

technical definition of exception

Answer 38

An object that is created at runtime, and has the error message.

Question 39

if a common method has “throws” keyword, it is called

Answer 39

common exception methods

Question 40

define a thread

Answer 40

a flow of control in a program is called a thread.

Question 41

Define FGT

Answer 41

Foreground Thread: a thread that executes programmers java logic.

Question 42

Define BGT

Answer 42

Background Thread: a thread that monitors the execution of foreground threads.

Question 43

Define address space

Answer 43

Temporary space created in memory for execution of method

Question 44

Define mutators and inspectors

Answer 44

same as setter and getter methods.