I was wondering if I could make it so a loop can end with typing in a command like end or -1. What I have now is
while ( gradeCounter <= 10 ) // loop 10 times
I would like to know how to have it loop infinitely till I end it.
3 Answers
Simply create a while loop and a condition to break it
while(true){
String inputString = //Get user input here
if(inputString.equals("Your Termination Text"))
break;
}
If you want to know how to get console input here is one method Java: How to get input from System.console()
Edit per comments below
double grades = 0;
int entries = 0;
while(true){
String inputString = //Get user input here
if(inputString.equals("Your Termination Text"))
break;
else{
grades += Double.parseDouble(inputString);
entries++;
}
}
double averageGrade = grades / entries;
Please keep in mind that this does not account for text that is not a number and also not your termination text. From the question it sounds like a low level CIS class and I don't think this will be an issue. If it is however you need to learn how to do try catch and some more input validation.
15 Comments
nhgrif
It's worth mention that the same thing can be done with all of the loops. Put the above loop body into
for(;;){//loop body from above} or do{//loop body from above}while(true); Just a matter of personal preference.
Joyal
If I have average = total / 10 How do I do average for infinite loop?
nhgrif
If you need to average, the
for loop is actually pretty good method. for(int i=0;;i++){//find sum, divide by i}
DotNetRussell
You can also use a less clean but just as effective counter declared outside of your loop then just increment it each iteration with counter++
nhgrif
@SamYonnou That concept is probably a bit to advanced for someone who would even post this original question...
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While(true) {} creates an infinite loop. A break command inside the loop breaks out of it. You'll have to detect whatever sort of event will occur inside the loop to determine if you should break.
I don't know what you're doing on a larger scale, but it could be a better idea to use Threads which don't loop infinitely and suck up processing power.
Comments
Yes, it is possible. Just make sure, there is a different thread that can handle some kind of input...
public class MyBreakableInfiniteLoop
public static void main(String[] args) {
MyRunnable r = new MyRunnable();
new Thread(r).start();
System.out.println("Press Enter to stop thread");
new Scanner(System.in).readLine();
r.stop = true;
}
public static class MyRunnable extends Runnable {
public volatile boolean stop = false;
public void run() {
while(!stop) {
//do nothing, preferably in a meaningful way
}
}
}
}
(aLso, I didn't take into count kill -9 as "input that breaks the infinite loop"...)
Scannerusage and compare the String/input to break the condition.