Reading from terminal without waiting for "newline" with Java

Asked Apr 14 '13 at 09:54

Active Apr 14 '13 at 09:59

Viewed 241 times

I'm trying to read every character that user inputs without waiting for a "newline".

This code doesn't work, as AFAIK Scanner waits for the newline character before sending input to the application

Scanner s = new Scanner(System.in);
if(s.hasNext()){
    char c = s.next().charAt(0);
}

I also tried with BufferedReader:

System.out.println("Input something: ");
BufferedReader b = new BufferedReader(new InputStreamReader(System.in));
while(!b.ready()){
    try {
        Thread.sleep(100);
    } catch (Exception e) {
    }
}
System.out.println("Now it's ready, i'm reading the first char");
char c = (char)b.read();

But the output is:

Input something:
> abcde
Now it's ready, i'm reading the first char

So it is always waiting for the newline character.

Is there any way to read user input without waiting for newline with Java?

Thanks, any help would be appreciated

asked Apr 14 '13 at 09:54

BackSlash

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why don't you just use `System.in.read()` ? – drone.ah Apr 14 '13 at 10:22
Because it waits for the newline character. – BackSlash Apr 14 '13 at 10:26
What about using a `BufferedInputStream` and checking if characters are `available()` ? – drone.ah Apr 14 '13 at 11:01
@drone.ah It also waits for newline character. – BackSlash Apr 14 '13 at 11:03
You need to put the console in raw mode, which isn't cross-platform. Maybe try jreadline or whatever the interface to deadline is. – Dave Newton Apr 14 '13 at 11:50

Reading from terminal without waiting for "newline" with Java

0 Answers0