Java Levels 0-2

Question 1

strings

Answer 1

“string”

must have quotation marks

String

Question 2

integers

Answer 2

whole #’s w/ no decimal point

weird math

int

Question 3

doubles/floating-point values

Answer 3

real numbers

numbers w/ decimal points

double

Question 4

booleans

Answer 4

true/false (LOWER CASE)

boolean

Question 5

operators

Answer 5

the symbols that we use to perform calculations on diff values

Question 6

arithmetic operators

Answer 6

+ - * / %

parenthesis used same as in math

order of operations same

Question 7

concatenation

Answer 7

if you “add” anything to a string, it will stick that value on to the string

“Hello” + “werld” = “Hellowerld”

50 + “8” = “508”

“Zoobah” + 0.5 * 3 = “Zoobah1.5”

Question 8

integer division

Answer 8

when 2 integers r divided, the result is always an integer

will chop off decimal part NOT round

6/4 = 1

2 / 3 = 0

1 / 5.0 = 0.2 (if ether of the values is a double, will do normal division)

Question 9

modulus division

Answer 9

only works on integers

gives the remainder of the first number divided by the second number

6 % 4 = 2

12 % 3 = 0

3 % 4 = 3 (if 1st # is less than 2nd #, answer is always 1st number)

Question 10

variables

Answer 10

named containers for values

fundamental tool for programming

must be declared

Question 11

variable declarations

Answer 11

statements, so must end in semicolons

int blah;

double aVariable;

String porty;

int ting, roo;

Question 12

assignments/statements

Answer 12

putting a value into a variable for storage

=

blah = 10;

aVariable = 0.6;

porty = “Teapot”;

ting = 10 / 5;

roo = blah / ting; can use other variables in math expression and assignment statements

Question 13

combining declarations & assignments

Answer 13

int abc = 12, def = 801;

double xyz = 10.5;

String ijk = “pointy hat”;

Question 14

self assignments

Answer 14

can use a variable on the right hand side of its own assignment

int fumu = 10;

fumu = fumu + 3;

fumu = fumu - 5;

Question 15

type mismatch

Answer 15

when variables r assigned values that don’t match their type

int abc = 10.0;

double def = 3; this works tho cuz Java can turn integers into doubles when necessary

Question 16

name conflict

Answer 16

w/in a Java program, no 2 variables can be declared w/ the same name, even if they r dif types

int neato;

String neato;

Question 17

import

Answer 17

brings in a class from Java’s class library, a large # of classes & methods written by the poeple who made Java, 2 help ppl use Java

Question 18

javax.swing.JOptionPane

Answer 18

a collection of useful methods that can pop up diff windows 2 do stuff

Question 19

showInputDialog

Answer 19

a method inside of JOptionPane

pops up a window tht lets the user type a string

will then assign the string tht was typed to the variable on the left side of the =

only works for Strings

Question 20

Integer.parseInt

Double.parseDouble

Answer 20

takes any String in the parenthesis & tries to turn it itno an integer(or double)

Question 21

condition

Answer 21

an expression that compares 2 values & gives a Boolean result(true/false)

5 > 12 (true)

3 > 7 (false)

6 >= 6 (true)

Question 22

conditional operators

Answer 22

< less than

> greater than

<= less than/equal to

>= greater than/equal to

== equal to

!= not equal to

don’t work w/ strings

Question 23

.equals()

Answer 23

bah.equals(wip) would give true if both bah & wip r the same string

Question 24

if

Answer 24

if (a < b) {

System.out.println("blah");

}

if the condition inside the parenthesis is true, then Jaca will do the code inside the curly braces. otherwise, skips it.

Question 25

else

Answer 25

if (a < b) {

System.out.println("blah");

} else {

a = a + 10;

}

The code inside the curly braces after the else keyword will be done if the condition turns out to be false

Question 26

else if

Answer 26

if (a < b) {

a = a - 5;

} else if (b > c) {

b = b + 9;

}

If 1st condition is false but 2nd is ture, will do 2nd code.

If 1st is true, then will do 1st code & skip else if

Question 27

if-else chains

Answer 27

You can put an if, lots of else ifs, and an else together in a “chain” of conditions

can have as many else ifs as u want, but only one if @ beginning and 1 else @ end

Java will work its way down the “chain” & do the code inside the curly braces for the 1st condition which is true

exclusive, so will only actually do the code b/w 1 set of curly braces

Question 28

branching

Answer 28

refers to the ability of the program to do diff things under diff conditions

Question 29

Boolean operators

Answer 29

&& and

|| or

! not

used only with conditions

Question 30

boolean order of operations

Answer 30

AND always before ORs unless parenthesis

math operators ALWAYS take precedence over Boolean operators

(x - 5 < 2) will do x - 5 first