Unit 2: Using Objects

Question 1

A _____ is an instance of a class with defined ______

Answer 1

object, attributes

Question 2

A _____ is the formal implementation, or blueprint, of the attributes and behaviors of an object

Answer 2

class

Question 3

Used to initialize the attributes of an object

Answer 3

constructor

Question 4

information passed/declared for a constructor within its parentheses

ex. public Person (int height, String name, boolean home)

Answer 4

formal parameters

Question 5

keyword used to make a new object

Answer 5

new

Question 6

A ____ has no parameters and sets the instance variables for the object to default values

Answer 6

no-argument constructor

ex. Dog ted = new Dog();

Question 7

The value an initialized variable has, or can be as a placeholder

Answer 7

null

Question 8

Define the behaviors for all objects of a class and consist of a set of instructions for executing the behavior

Answer 8

methods

Question 9

Methods that don’t have return values, so they just perform a action

Answer 9

void methods

Question 10

constructors with the same name, but different parameters

Answer 10

overloading constructors
(CANNOT have two with the exact same parameters and name)

Question 11

Methods that return a value that is the same type as the value given to manipulate (saved as variable, DOES NOT print calculation)

Answer 11

non-void methods

ex. average = calculation for average;
return average;

Question 12

String objects are _____.

Answer 12

immutable (no method can change the value of that particular String object)

Question 13

command to print a new line in java in a string

Answer 13

\n

Question 14

value returned by indexOf() method if string doesn’t contain letter/phrase

Answer 14

-1

Question 15

String method that returns a substring from the first index value to the last index value minus 1

Answer 15

String substring(int from, int to)

Question 16

String method that returns a substring from the index value to the end of the string

Answer 16

String substring(int from)

( returns substring(from, length) )

Question 17

method that tests if strings are the exact same letters in the exact same order

Answer 17

word1.equals(word2);

(note: put boolean in front to return true or false if they equal/don’t equal)

Question 18

String .compareTo Values (tests which strings come before another by length)

> 0 :
= 0 :
< 0 :

Answer 18

> 0 : longer than other string
= 0 : equal to other string
< 0 : shorter than other string

(note: all in reference to 1st string)

Question 19

methods that belong to a class instead of objects of a class

Answer 19

static methods

Question 20

Math.random() returns ____.

Answer 20

A double that is between 0.0 inclusive and less than 1.0

Question 21

Basic format for making a new object:

Answer 21

className objectName = new className(parameters);

Question 22

The first index of a string is ___.

Answer 22

0

Question 23

line of code used to make a substring:
What index values does the substring take?

Answer 23

str.substring(x, y);
from x to the index value before y

Question 24

line of code to tell you length of substring:

Answer 24

str.length();

Question 24

function to get a random number:
what values does it make?
what do you have to do to make them whole values?

Answer 24

• Math.random();
• random number including 0 but less than 1.0
• usually gets cast to (int)

Question 24

function to take absolute value:
function to take square root:
function to use exponent:

Answer 24

• Math.abs(num);
• Math.sqrt(num);
• Math.pow(num, exponent);

Question 25

formula to know range of numbers for Math.random()

Answer 25

(max number - min number + 1)
add the first number in range, multiply math by the parentheses