Unknown Vocab Lessons #1-14

Question 1

indices

Answer 1

plural form of index, referring to the numbers that begin to be counted up from zero, like those used with substring

Question 2

what are the two methods that will turn everything lower/upper case?

Answer 2

toUpperCase() and toLowerCase()

Question 3

in increment, what is the difference between x++ and ++X

Answer 3

x++ increments x AFTER the whole statement has been read whereas ++x increments it immediately. The same applies for decrement (x–, –x)

Question 4

truncation

Answer 4

when the program throws away the fractional part of an integer division, so 7/2 is not 3.5, it is 3. It always rounds down.

Question 5

what does Math.ceil(double x); do?

Answer 5

rounds up to the nearest whole number (so if x = 57.2, then Math.ceil(x) = 58.0

Question 6

what does Math.floor(double x) do?

Answer 6

rounds down to the nearest whole number so if

x = 57.2 then Math.ceil(x) = 57.0

Question 7

what does Math.pow(double b, double e); do?

Answer 7

does b to the power of e

Question 8

what does Math.random() do for doubles?

Answer 8

returns a random value in the range of 0

Question 9

what does Math.round(double x) do?

Answer 9

rounds to the NEAREST whole number (does not simply round down).

Question 10

how else can you assign a value to a boolean besides saying boolean x = true/false; ?

Answer 10

You can set the boolean equal to a operation that will either be true or false
ex: boolean dave = true; //OR
boolean dave = 3>2; //true

Question 11

how can you compare two Strings without caring about upper or lower case??

Answer 11

String y = “fUnKyTOWN”;
if(y.equalsIgnoreCase(“funkytown”){
…………………………….
}

Question 12

what does continue; do?

Answer 12

all code after the continue statement is skipped for that particular iteration in the loop, though the increments still continue as normal

Question 13

is it legal to convert a String to a char?

Answer 13

Not without using a method besides pure assignment (‘A’ is illegal but “A” is legal)

Question 14

what kinds of quotes do chars use?

Answer 14

‘single quotes’ not “double”

Question 15

Is it legal to store type char in an int? If so, why?

Is it legal to store type int in char?

Answer 15

Yes, because the char letters will be read as ASCII hexadecimal letters. It is illegal to store ints in chars (but you can cast to char)

Question 16

how to convert from char to String

Answer 16

concatenate empty “” quotes with the char variable
ex:
char amy = ‘D’;
String jake = ““+amy;

Question 17

how to convert from String to char

Answer 17

String sam = “T”;

char bob = sam.charAt(0); //bob now equals T

Question 18

list the commands used to identify the properties of char values (there are 6)

Answer 18

Character.isLetter(char)
Character.isDigit(char)
Character.isLowerCase(char)
Character.isUpperCase(char)
Character.isWhitespace(char) //WHITESPACE IS ONE WORD
Character.isLetterOrDigit(char)

Question 19

what are the two commands used to convert chars to upper and lowercase?

Answer 19

Character.toUpperCase(char)

Character.toLowerCase(char)

Question 20

what leading characters indicates that a number is in hex format?

Answer 20

0x

Question 21

what leading characters indicates that a number is in binary form?

Answer 21

0b

Question 22

what leading character indicates an octal number?

Answer 22

0

Question 23

how to convert integers into binary, hexadecimal, and octal?

Answer 23

Integer.toHexString(int x)
Integer.toBinaryString(int x)
Integer.toOctalString(int x)

Question 24

what is the alternate method of converting numbers to hex, octal, etc. ?

Answer 24

Integer.toString(int x, base #);

ex: Integer.toString(675, 16);

Question 25

how to use parseInt to convert from a strange base back to decimal??

Answer 25

Integer.parseInt(“123kn23”, 35);

^ converts “123kn23” in base 35 back to decimal