11.10 Map

src/concurrency/IntGenerator.java

@@ -0,0 +1,9 @@
+package concurrency;//: concurrency/IntGenerator.java
+
+public abstract class IntGenerator {
+  private volatile boolean canceled = false;
+  public abstract int next();
+  // Allow this to be canceled:
+  public void cancel() { canceled = true; }
+  public boolean isCanceled() { return canceled; }
+} ///:~