Chapter 1 -getting started

Question 1

ideology of OOP

Answer 1

views a program as consisting of objects that interact with one another by means of actions called methods

Question 2

objects of the same kind are said to have the same…

Answer 2

type or be in the same class

Question 3

Applications vs applets

Answer 3

application - regular program is a class that has a method named main 
when its is run, the run-time system automatically invokes the main method 

applet - application meant to be run from a web browserO

Question 4

Obj used to sending output to screen

Answer 4

System.out

Question 5

what is println

Answer 5

method or action that the System.out obj performs

Question 6

=

Answer 6

assignment

Question 7

==

Answer 7

are these two things in the same memory location?

Question 8

.equals()

Answer 8

are these things the same

Question 9

define source code

Answer 9

program written in a high level language - input to the compiler program

Question 10

object code

Answer 10

translated low level language program

output from the compiler program e.g. Java byte code

Question 11

what does javac do?

Answer 11

Each class is compiled with the command javac followed by the name of the file in while the class resides. The result is a byte code program whose filename is the sa,e as the class name followed by .class

Question 12

syntax vs semantics

Answer 12

syntax - like the grammar, semantics - meaning of the things written while following the syntax rules of a language

Question 13

Syntax error vs run time error vs logic error

Answer 13

syntax - code wont compile
run time - error that isnt detected until the program is run
logic error - mistake in the algorithm for a program

Question 14

case sensitive

Answer 14

yes

Question 15

keywords and reserved words

Answer 15

public class void static 
System String println - predefined in libararies can be changed but dangerous

Question 16

declaring more than one variable at a time

Answer 16

double one, two, three;

Question 17

primitive data types

Answer 17

boolean
char - 2 bytes
byte
short
int
long
float
double

Question 18

initializing variables

Answer 18

int initial = 50, finalcount;

Question 19

shorthand

Answer 19

count +=2 - count = count+2

amount =count1+count2 –> amount = amount(count1+count2)

Question 20

assignment compatibility

Answer 20

int intvar = 2.99 - illegal
exceptions:
int can go into a double

Question 21

auto type casting hierarchy

Answer 21

byte - short - int - long - float - double

Question 22

from a float to int

Answer 22

truncation - 2.9 – 3

Question 23

type coercion -

Answer 23

auto type cast

Question 24

explicit type cast

Answer 24

int i = (int) 5.5

Question 25

arithmetic between int-int and int-double

Answer 25

int -int = ans will be int

int-double - double

Question 26

round off errors

Answer 26

15.0/2 = 7.5

15/2=2 - truncation

Question 27

increment and decrement

Answer 27

++

–

Question 28

pre vs post decrements

Answer 28

pre:
if n = 2: 2++n = 6
post
if n = 2: 2n++ = n = 4…n is first assigned and then incremented

Question 29

the string objects

Answer 29

no primitive types
String a = “hello”
concatination

Question 30

define a class

Answer 30

the name for a type whose values are objects

Question 31

what is an object

Answer 31

entities that store data and take actions

Question 32

Some string methods

Answer 32

.length()
.equals()
equalsIgnoreCase()
.toLowerCase()
.toUpperCase()
.trim() 
charAt(position)
substring(start)
substring(start,end)
indexOf()

Question 33

escape sequences

Answer 33

basically just use \

Question 34

ascii vs unicode

Answer 34

ascii - contains all the characters used on an english keyboard
unicode - incl ascii plus other language characters

Question 35

program documentation

Answer 35

• javadoc

- extract documemntation from block comments in the classes that you define = /**