Computer Science Java

Front 1

method call

Back 1

command that sends the computer to another method

Front 2

parameters

Back 2

- statements that appear in the ( ) following the name of a method

Front 3

formal parameters

Back 3

appears in ( ) after the method name- identifies the name and type of variables used in the method

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actual parameters

Back 4

gives value to formal parameters

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return

Back 5

specifies the value to be returned by a method, a command that causes the method to end immediately

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Top-down Design

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Problem solving strategy that breaks down each step into smaller steps

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Array

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a big variable that combines multiple elements all having the same type and same name; we distinguish among the elements using their position in the array

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Object

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an instance of the class

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New

Back 9

keyword that initializes objects, new says an instance has been created

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Public

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can only be assigned to one class per program

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Constructor

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a method whose name is the same as the class, it is called automatically when a new instance of the class is created

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where does the program begin?

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the program will begin at which ever method is called main

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2 reasons for methods

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They shorten programs
They break large programs into bite size pieces

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What does it mean to call or invoke a method?

Back 14

to make it go to another method

Front 15

Paramters are passed by ______. what does that mean?

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value. This means that the actual parameters are copied into parameters when a method is called

Front 16

How do you declare an array?

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type[]name;
a= new type[number of slots in the array]

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Code to determine the capacity of an array?

Back 17

Arrayname.length

Front 18

code to find the smallest value in an array?

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Assume first array element is the smallest
Smallest= a[0]
Use a for loop to compare each element to the smallest

Front 19

code to find the sum of the numbers in an array?

Back 19

Total= 0
For loop adding each element in array to total

Front 20

3 steps to using a file

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Open, Use, Close

Front 21

code to open a file

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scanner= name;
name=new scanner(new file(“name of file”)

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code to close a file

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name.close

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code to determine if there is more info in the file

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name.hasnextline()

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Problems with files

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Must import file class:
import java.io.File;
public static void main (String [] args) throws IOexception
Must handle possible IO exceptions:
import java.io.IOExceptions

Front 25

what type of design does structured programing use?

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Uses top-down design

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what are the basic building blocks for structured programming?

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Methods are the basic building blocks for designing and writing programs

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How are classes used in structured programming?

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Classes are viewed as a convient way to way to combine multiple elements having different types

Front 28

what type of design does object oriented programing use?

Back 28

uses object oriented design

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What are the basic building blocks in object oriented design?

Back 29

classes are the basic building blocks

Front 30

how are methods used in object oriented design?

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methods are used to perform actions within a class

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what is the focus of object oriented design?

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focuses on noun- things they know and things they can do

Front 32

how can a class be used with in other classes?

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a class can be used as a variable type in other classes

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instances can be passed as_____.
whenever an instance is changed in a method, it is_________.

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parameter.
it is changed in main - the reference is created and destroyed

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purpose of a constructor

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to initialize variables in a class (with values rather than the default 0 and null) as soon as they are created

Front 35

Constructors are _________(3)

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always public, never static, and it has no return type

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purpose of a toString

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whenever an object is printed, this method returns info rather than reference

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toString Format

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public String toString()
return (“blah blah blah”)

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%s

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place holder for string

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%d

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place holder for int

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%f

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place holder for float/ double

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code to introduce formatted print statement

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System.out.printf

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code to justify right

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% field width .number of decimal places type (justifies right)

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code to justify left

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%- field width .number of decimal places type (justifies left)