Why is this do-while loop not stopping?

Question

The purpose of this loop is to stop as soon as a period key is typed, but it is not working and I did not understand why.

import java.io.IOException;


public class ControlFlowTest {

public static void main(String[] args) throws java.io.IOException {
    char ch ;

    do{
        ch = (char) System.in.read();
    }while(ch != '.');

}

https://ericlippert.com/2014/03/05/how-to-debug-small-programs/ — , Aug 18 '17 at 19:21
I think the OP's problem is that the `read()` call is blocking until an EOL is given, which is not what they're expecting to happen. — azurefrog, Aug 18 '17 at 19:24
Possible duplicate of [Why can't we read one character at a time from System.in?](https://stackoverflow.com/questions/4007534/why-cant-we-read-one-character-at-a-time-from-system-in) — shmosel, Aug 18 '17 at 19:26

gyleg5 · Accepted Answer · 2017-08-18T23:58:10.767

0

You will want to use Scanner as System.in.read() will block until a carriage return is entered. Try this:

import java.io.IOException;

public class ControlFlowTest {
    public static void main(String[] args) throws java.io.IOException {
        char ch ;

        Scanner scanner= new Scanner(System.in);
        do {
            ch = scanner.next().charAt(0);
        } while(ch != '.');
    }
}

edited Aug 18 '17 at 23:58

answered Aug 18 '17 at 19:33

gyleg5

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This will do the same thing, only worse. With your solution entering "abc." and pressing enter will not exit the loop. – Oleg Aug 19 '17 at 00:21

Why is this do-while loop not stopping?

1 Answers1