CSCE 111
nested loops
- a loop that is inside another loop - necessary when a task performs a repetitive operation and that task itself must be repeated
while loop
- has two main parts: 1) a Boolean expression that is tested for a true or false value 2) a statement or block of statements that is repeated as long as the expression is true - pretest loop
++ and --
- operators that add and subtract one from their operands - can work in prefix and postfix mode
loop
- part of a program that repeats - control structure that causes a statement or group of statements to repeat
for loop
- pretest loop - this loop is ideal for performing a known number of iterations - count-controlled loop
while loop, do-while loop, and for loop
Java's three looping control structures
throws IOException
PrintWriter objects are capable of throwing exceptions, which clause is written in the header
objects
Scanner object, Random object, and PrintWriter object are al examples of _______
println
The PrintWriter class's _______ method writes data to a file
inner, outer
______ loops complete their iterations before _______ loops do
running total
a sum of numbers that accumulates with each iteration of a loop
sentinel
a value that signals when the end of a list of values has been reached
copy
all arguments of the primitive data types are passed by value, meaning that only a ______ of an argument's value is passed into a parameter value
user controlled loop
allows user to decide the number of iterations
created in memory, class
before a specific type of object can be used by a program, that object has to be ___________, and before that you must have a _____ for that object
class
code that describes a particular type of object, specifies the data that an object can hold (fields) and the actions that an object can perform (methods)
method name
descriptive name for a method
data type
each parameter variable in a parameter list must have its ________ listed before its name
iteration
each repetition of a loop
instance
each time you create a Scanner object, you are creating a(n) _______ of the Scanner class
object
has two general capabilities: 1) it can store data (fields) 2) it can perform operations (methods)
same throws clause
if a method calls another method that has a throws clause in its header, then the calling method should have _________
return type
key word void, means the method is a void method and does not return a value
semicolons
method headers are never terminated with ________
@param tag
provides a description of each parameter
@return tag
provides a description of the return value
--
the decrement operator
if(file.exists())
this creates a File object representing the file
update expression
this expression executes at the end of each iteration, a statement that increments the loop's control variable
initialization expression
this expression is used to initialize a control variable to its starting value
while(inputFile.hasNext())
this expression reads lines from the file until no more are left
do-while loop
this loop always performs at least one iteration, even if the boolean expression is false to begin with
while loop
this looping control structure works like an if statement that executes over and over
continue statement
this statement causes a loop to stop its current iteration and begin the next one
break statement
this statement causes a loop to terminate early
count-controlled loop
this type of loop must possess three elements: 1) it must initialize a control variable to a starting value 2) it must test the control variable by comparing it to a max value 3) it must update the control variable during each iteration, usually done by incrementing the value
parameters
variables that receive argument values that have been passed to a method
instance
when a program is running, it can use the class to create, in memory, as many objects of a specified type as needed - each object that is created from this class is called a(n) _________ of the class
throws an exception
when an unexpected event occurs in a Java program, it is said that the program _________
parenthesis
when passing a variable as an argument, write the variable name inside __________ of a method call
local variable
when this is declared inside a method, it is not accessible outside the method
value-returning method
when writing this type of method, you must include its data type in the method header public static int sum(int num1, int num2)
while loop
while(BooleanExpression) Statement;
appending to a file
writing new data to the end of the data that already exists in the file
local variable
you may use a parameter variable to initialize a _________, but they must be given a value first before they can be used
do-while loop
- posttest loop - its boolean expression is tested after each expression - inverted while loop - terminated with a semicolon
accumulator
- the variable used to keep the running total - initialized with a starting value of 0
Random class
- this class provided by Java is used to generate random numbers - part of the java.util package
methods
- used to break a complex program into small, manageable pieces - a collection of statements that perform a specific task
arguments
- values that are sent into a method - can pass contents of variables and values of expressions as these
infinite loop
- you can create this kind of loop by accidentally placing a semicolon after the first line of a while loop
do not, do
______ place semicolons at the end of while and for loops, but _____ place a semicolon at the end of do-while loops
hasNext
a Scanner class method that can be used to determine whether the file has more data that can be read
test expression
a boolean expression that controls the execution loop, as long as this expression is true, the body of the for loop will repeat
input file
a file that a program reads data from
output file
a file that a program writes data to, program stores output in the file
text file
a file that contains data that has been encoded as text, using a scheme such as unicode
binary file
a file that contains data that has not been converted to text
call statements
a method is executed by _________
executing
a method's local variables only exist while the method is ________, once the method is done doing this, the local variables are destroyed
scope
a parameter variable's _______ is the method in which the parameter is declared, no statement outside the method can access the parameter variable by its name
exception
a signal indicating that the program cannot continue until the unexpected event has been dealt with
object
a software component that exists in the computer's memory and performs a specific task
parameter variable
a special variable that holds a value being passed into a method
parenthesis
in while and do-while loops, you must close the boolean expressions in ________
method calls
method headers and return types are written in method headers, but never in __________
hierarchal
methods can be called in this type of layered fashion
PrintWriter
pass the name of a file you wish to open as a string to this class's constructor
nextLine method
the Scanner class's ______ method reads a line of input, and returns the line as a string
object's method
the actions that an object can perform
data type
the argument's _________ must be compatible with the parameter variable's ________
object's field
the data that an object can hold
++
the increment operator
method modifiers
the key words public and class
functional decomposition
the process of breaking down a problem into smaller pieces, instead of writing one long method that contains all of the statements necessary to solve a problem, small methods are written, which each solace a specific part of the problem
input validation
the process of inspecting data given to a program by the user and determining whether its valid
priming read
the read operation that takes place just before the loop
header and a body
the two parts needed to create a method
String objects
these objects are immutable in the Java language, meaning they cannot be changed
control variable
this controls the number of time the loop iterates
conditional loop
this type of loops executes as long as a particular condition exists
value-returning method
this type of method returns a value to the statement that called it ex: the Random class's nextInt method
void method
this type of method simply executes a group of statements and then terminates ex: System.out.println
write data to
to __________ a file, you create an instance of the PrintWriter class
methodName();
to call a method, you must write a call statement, which is formatted like __________
&& and ||
to connect multiple boolean expressions in the test expression use ________
Random rand = new Random();
to create an object from the Random class
append data to an existing file
to do this, you must first create an instance of the FileWriter class, pass two arguments to the FileWriter constructor: a string containing the name of the file and the Boolean value true
commas
to execute more that one statement in the initialization expression and the update expression you separate the statements by _______
String friendName = inputFile.nextLine();
to read strings from a file
semicolons
to separate the initialization, test, and update expressions in a for loop, place _______ in between them
import statement
to use classes that work with files, you will place a _________ near the top of your program
exists method
use the File class's ________ method to determine whether a file exists
FileWriter and Scanner
use these class's to read data from a file
PrintWriter and FileWriter
use these class's to write data to a file
cast operator
use this operator to convert a value manually to a lower-ranking data type
comments
you must always document a method by writing _______ that appear just before the method's definition, which provides a brief explanation of the method's purpose
return statement
you must have this statement in a value-returning method because is causes the method to end execution and return a value to the statement that called the method
throws IOException
you must write this clause in the header of any method that passes a File object reference to the Scanner class constructor
Scanner class
you use this class to read input from a file, to do this, pass a reference to a File object