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Conditional expressions

Concept A conditional expression is a shorthand for an if-statement that assigns different values to one variable:

if (expression) var = value1; else var = value2;

This can be rewritten more concisely as:

var = (expression) ? value1 : value2;

The boolean-valued expression is evaluated: If the result is true, value1 is assigned to var ; if not, value2 is assign to var .

Program: Control02.java

// Learning Object Control02 //    conditional expressionspublic class Control02 {     public static void main(/*String[] args*/) {         int year = 2001;        int month = 2;         int days;        if (month == 2)             days = (year % 4 == 0) ? 28 : 29;        else if (month == 4 || month == 6 ||                 month == 9 || month == 11)            days = 30;         else            days = 31;         System.out.println(days);    } }

The program computes the number of days in a month taking leap years into account.

  • The variables are allocated and the first two, year and month , are given initial values.
  • The expression month == 2 evaluates to true, so the statement following the expression is executed. Jeliot will display Choosing then-branch to emphasize this.
  • The inner statement is an assignment statement with a conditional expression. The expression is evaluatedand its result is false, so the value after the colon is assigned to the variable. Jeliot will display Choosing else-branch .
  • The value of days is printed.

Exercise Complete the program with the correct computation for leap years: a year divisible by 100 is not a leap year unless itis divisible by 400.

Exercise Rewrite the entire if-statement as nested conditional expressions.

While loops

Concept A loop enables the execution of a statement (including a block of statements within braces) an arbitrary number of times.This statement is called the loop body . In a while loop, an expression is evaluated before each execution of the loop body,and loop body is executed if and only if the expression evaluates to true.

Program: Control03.java

// Learning Object Control03 //    while loopspublic class Control03 {     static int LIMIT = 100;    public static void main(/*String[] args*/) {        int factorial = 1;         int n = 1;        while (factorial < LIMIT) {             System.out.println(factorial);            n++;             factorial = factorial * n;        }     }}

This program prints all factorials less than LIMIT = 100 , namely, 1 ! = 1 , 2 ! = 2 , 3 ! = 6 , 4 ! = 24 .

  • The static constant and the two variables are allocated and initialized.
  • Then, and each time the keyword while is reached, the expression is evaluated. If it is true, execution proceeds with the loop body, andJeliot displays Entering the while loop the first time and Continuing the while loop on subsequent occasions.
  • The statements of the loop body are executed. They print the value of the current factorial, increment the counterand compute the new factorial; then, control returns to the while-expression.
  • If and when the expression evaluates to false, execution proceeds with the statement following the loop body.Jeliot displays Exiting the while loop .

Questions & Answers

what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Learning objects for java (with jeliot). OpenStax CNX. Dec 28, 2009 Download for free at http://cnx.org/content/col10915/1.2
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