Package nz.org.riskscape.engine.cli

Class InterruptibleReadline

java.lang.Object

nz.org.riskscape.engine.cli.InterruptibleReadline

public class InterruptibleReadline
extends Object

Has a routine for reading a line of input from the console in a way that shouldn't block, even though it uses blocking I/O calls. That allows the reading thread to be interrupted, which we can use to support ctrl-c while a user is entering input.

This is implemented by checking InputStream.available() and then sleeping for a small interval when nothing can be read. A human shouldn't be able to detect the pause, but it's still long enough to avoid spin-locking a CPU.

Constructor Summary

Constructors

Constructor	Description
InterruptibleReadline()

Method Summary

Modifier and Type	Method	Description
static String	readline(InputStream stdin)	Read a line of input from an input stream, presumably stdin.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

InterruptibleReadline

public InterruptibleReadline()

Method Details

readline

public static String readline(InputStream stdin)
                       throws IOException,
InterruptedException

Read a line of input from an input stream, presumably stdin.

Parameters:

stdin - An InputStream to read a line from. Note that if stdin doesn't support mark (InputStream#markSupported returns true), and it is wrapped to force it to support it, then you must make sure all other users or stdin use the wrapped/buffered version, or they may miss the first character after a call to readline if '\r's appear in the stream.

Returns:

the string that was read, with the line terminator removed.

Throws:

IOException - if there was an io error reading from stdin

InterruptedException - if the thread was interrupted while waiting to receive keypresses