chapter 3

how do you format a parameter in a uml?

( name : type)

in a UML, if the instance variable private, you put a...

- (minus)

what are all the primitive types?

Boolean, byte, char, short, int, long, float, and double.

explain what is going on in this statement Gradebook myGradeBook = new GradeBook(); go left to right

Gradebook declares what type of variable myGradeBook will be, myGradeBook names the variable, "=" initializes myGradeBook with the result of the class instance creation expression of new GradeBook(), new creates a new object of the class specified, and the () are just there for now.

each parameter must specify...

a type and variable name.

keyword "public" is an...

access modifier

private is a...

access modifier

variables or methods declared with access modifier private are....

accessible only to methods of the class in which they're declared.

main methods are...

always called on by the JVM when program is exe.d

a client of an object is..

any class that calls the objects methods

the parameter list may contain....

any number of parameters.

what are reference types?

anything that not a primitive type. classes which specify the types of objects

why is java known as a extensible language?

because each new class you make becomes a new type that can be used to declare variables and create objects.

even though a constructor is a method, why can't it even have void?

because it can never be able to return values.

a constructor must have the ____ ____ as the class.

same name

classes often provide public methods to allow clients to ____ or ____ private instance variables.

set; get

float represents... (digits too)

single-precision floating-point numbers and can represent up to seven significant digits

return type (provide an example)

specifies the type of data the method gives back to it's caller after performing it's task. VOID

what does method setCourseName do in the gradebook?

stores a course name in a gradebook

the empty parentheses after the method name indicate what?

that it is a method and that it doesn't need any extra info to complete its task.

the parentheses after the method name indicate what?

that it is a method.

return type void means....

that method will perform a task but will not return (give back) any info to its calling method. It instead gives it to the program for use.

no parameters indicate...

the method doesn't need any parameters at all

do the argument and parameters names always have to match?

the name has to match

%.2f means...

the number of decimal places (in this case 2) that should output to the right of the decimal point in the floating point number. it rounds if it needs to

the number of decimal places that should output to the right of the decimal point in the floating point number.

the numbers precision

you put : String after the () in a UML when...

the return type is a string

what does "+" mean in a UML?

the the operation is a public operation. basically, additional info

a client of an object call the class's public methods...

to manipulate the private fields of an object of the class.

arguments

values that are supplied by a method call for each of the method's parameters.

in a class declaration, attributes are represented as....

variables

local variables

variables declared in the body of a particular method

what is a field

variables declared inside a class but outside methods.

What do we do to test classes without a main method?

we make a driver class, one that has a main method

when is a case where you don't have to declare the variable?

when it is the instance variable of the class

when can you not create a Gradebook object with new Gradebook()? why? (hint class GradeBook has a constructor)

when you've declared any constructors for a class. because now there is no default to go to any more; since you've declared a constructor, one have to enter in a name yoursel.

how do you put a construct with it's class, type, and name of that type in a uml?

«constructor» Account( typename : type )

what should a parameter list look like?

comma separated list inside the parentheses.

declaring instance variables with access modifier private is known as...

data hiding or information hiding.

what two primitive types store floating point numbers?

float and double

decimal numbers in source code are known as...

floating-point literals

%f is for...

floats and doubles

when you put a constructor in a uml, you put ____ around it.

guillemets « »

where do constructors go in a uml diagram?

in the third box, at the top

primitive-type instance variables are.... (initialization)

initialized by default

local variable are not... (initialization)

initialized by default.

public means...

it can be called from methods of other classes

what are some properties of local variables?

it can only be used in the method it is declared in, when the method terminates, the local variable terminates

what does it mean for a displayMessage to have a empty parameter? ()

it does not require any additional information to perform it's task

Method nextLine reads characters typed by the user until....

it encounters the newline character, then returns a String containing the characters up to, but not including, the new line. Newline is discarded.

double is preferred because....

it is more accurate

what does method getCourseName do in the gradebook?

it obtains the course name

in public String getCourseName() { return courseName; } what does "String" represent?

it's return type

parameter

its value helps the car to determine how fast to accelerate

how do you use a Scanner without importing?

java.util.Scanner input = new java.util.Scanner( System.in );

encapsulating is basically...

making something private.

myGradeBook.displayMessage(); is an example of a...

method call

String courseName = input.nextLine(); what does next do?

next reads individual words.

floating-point number

number w/ decimal point

one meaning of get.

obtain values of

what does a UML class diagram look like and what are the different slots for?

one big rect. with 3 smaller rects in it. the top has class name, middle has attributes, and bottom has methods.

a methods can require... (something about parameters)

one or more parameters that rep. additional info it needs to perform its task.

a primitive-type variable can store exactly...

one value of its declared type at a time

Java's types are divided into ________ and _________.

primitive types; reference types.

most instance-variable declarations are preceded with the keyword...

privatE

how do you declare an instance variable?

private String Name; put it outside of any method statement bodies.

if you want to add a custom initialization to an object you create, you must...

provide a special method called a constructor.

the access modifier of a constructor is normally...

public

When you use an object of another class, a ______ to the object is required to ____ (call) its methods.

reference; invoke

what are reference types normally called?

references

1. Programs use variables of reference types to... 2.Such a variable is said to...

1. store the locations of objects in the computers memory. 2.refer to an object in the program.

how do you write a constructor?

[access modifier] [class name]( [type] [variable] )

how do you initialize objects with multiple data items? (constructor)

[access modifier] [object name]( [type 1] [name], [type 2] [name] )

the constructor of an object with custom initialization needs to have...

a parameter with it's type.

one meaning of set.

assign values to

fields are (variables)

attributes that are represented as variables in a class declaration. however they are outside the bodies of the class's method declarations.

how do double and float differ?

double can store larger values than float, and also with finer detail (more digits to right of decimal)

double represents.... (amt of memory and digits)

double-precision floating-point numbers and they need twice the amount of memory that floats and provide up to 15 digits

a call to the constructor is indicated by the....

parentheses after the class name during object declaration

in order to initialize the name the objects of the class, you must specify it in the....

parentheses after the class name during the declaration of the object ex. GradeBook myGradeBook = new GradeBook( "INSET NAME HERE")