starting with java chapter 5
while loop
1. boolean expression that is tested for a true or false value 2. statement or block of statements that is repeated as long as the expression is true (repeats until boolean expression is false) pretest loop, which means that it tests its expression before each iteration
nested loop
a loop that is inside another loop
count-controlled loop
a loop that repeats a specific number of times
user-controlled loop
allows the user to decide he number of iterations
test expression
boolean expression that controls the execution of the loop
continue statement
causes a loop to stop its current iteration and begin the next one
break statement
causes a loop to terminate early
loop header
consists of the key word while followed by a boolean expression enclosed in parentheses
text file
contains plain text may be opened in a text editor such as Notepad
binary file
contains unformatted binary data, you cannot view its contents with a text editor
loop control variable
controls the number of times that the loop iterates
iteration
each repetition of a loop
conditional loop
executes as a long as a particular condition exists
update expression
executes at the end of each iteration
input file
file from which a program reads data
output file
file to which program writes data called an output file because the program stores output in the file
for loop
ideal for performing a known number of iterations pretest loop, tests its boolean expression before it performs an iteration
delimiter
item that separates other items
counter variable
keeps a count of the number of iterations
initialization expression
normally used to initialize a control variable to its starting value
postfix mode
operator is placed after the variable
prefix mode
operator is placed before the variable name
++ and--
operators that add and subtract one from their operands
loop
part of a program that repeats control structure that causes a statement or group of statements to repeat
the do-while loop
posttest loop ideal in situations where you always want the loop to iterate at least once
do-while loop
posttest loop, which means its boolean expression is tested after each iteration must be terminated with a semicolon
the while loop
pretest loop ideal in situation where you do not want the loop to iterate if the condition is false from the beginning. ideal if you want to use a sentinel value to terminate the loop
the for loop
pretest loop that has built-in expressions for initializing, testing, and updating these expressions make it very convenient to use a loop control variable as a counter. for loop is ideal in situations where the exact number of iterations is known
input validation
process of inspecting data given to a program by the user and determining if its valid
Java API
provides several classes that you can use for writing data to a file and reading data from a file
priming read
read operation that takes place just before the loop
exception
signal indicating that the program cannot continue until the unexpected event has been dealt with
buffer
small holding section of memory
read position
special value is internally maintained for that file
running total
sum of numbers that accumulates with each iteration
any method that uses a PrintWriter object must have a
throws IOException clause in its header
Scanner class and the File class
to read data from a file
PrintWriter class optionally FileWriter Class
to write data to a file
sentinel
value that signals when the end of a list of values has been reached
accumulator
variable used to keep the running total variable initialized with a starting value
can be used to create input routines that repeat until acceptable data is entered
while loop