Java: how to abort a thread reading from

Heinz Kabutz’s newsletter shows how to abort reads:

import java.util.concurrent.*;

class ConsoleInputReadTask implements Callable<String> {
  public String call() throws IOException {
    BufferedReader br = new BufferedReader(
        new InputStreamReader(;
    System.out.println("ConsoleInputReadTask run() called.");
    String input;
    do {
      System.out.println("Please type something: ");
      try {
        // wait until we have data to complete a readLine()
        while (!br.ready()) {
        input = br.readLine();
      } catch (InterruptedException e) {
        System.out.println("ConsoleInputReadTask() cancelled");
        return null;
    } while ("".equals(input));
    System.out.println("Thank You for providing input!");
    return input;

public class ConsoleInput {
  private final int tries;
  private final int timeout;
  private final TimeUnit unit;

  public ConsoleInput(int tries, int timeout, TimeUnit unit) {
    this.tries = tries;
    this.timeout = timeout;
    this.unit = unit;

  public String readLine() throws InterruptedException {
    ExecutorService ex = Executors.newSingleThreadExecutor();
    String input = null;
    try {
      // start working
      for (int i = 0; i < tries; i++) {
        System.out.println(String.valueOf(i + 1) + ". loop");
        Future<String> result = ex.submit(
            new ConsoleInputReadTask());
        try {
          input = result.get(timeout, unit);
        } catch (ExecutionException e) {
        } catch (TimeoutException e) {
          System.out.println("Cancelling reading task");
          System.out.println("\nThread cancelled. input is null");
    } finally {
    return input;

Now, I don’t know whether this approach leaks, isn’t portable or has any non-obvious side-effects. Personally, I would be reluctant to use it.

You might be able to do something with NIO channels and file descriptors – my own experiments with them didn’t yield any results.

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