Java new feature: threading
/*
License for Java 1.5 'Tiger': A Developer's Notebook
(O'Reilly) example package
Java 1.5 'Tiger': A Developer's Notebook (O'Reilly)
by Brett McLaughlin and David Flanagan.
ISBN: 0-596-00738-8
You can use the examples and the source code any way you want, but
please include a reference to where it comes from if you use it in
your own products or services. Also note that this software is
provided by the author "as is", with no expressed or implied warranties.
In no event shall the author be liable for any direct or indirect
damages arising in any way out of the use of this software.
*/
import java.io.IOException;
import java.io.PrintStream;
import java.math.BigInteger;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.Date;
import java.security.SecureRandom;
import java.util.Random;
import java.util.concurrent.Callable;
import static java.util.concurrent.TimeUnit.*;
public class ThreadTester {
private int[] posArray = new int[] {1, 3, 6, 3, 4, 2, 5};
private int[] negArray = new int[] {-2, -8, -3, -9, -10};
public ThreadTester() {
}
public void testBubbleSort(PrintStream out) throws IOException {
Thread t1 = new BubbleSortThread(posArray);
t1.start();
out.println("Testing with postive numbers...");
// Wait for the thread to complete
try {
t1.join();
printArray(posArray, out);
} catch (InterruptedException ignored) { }
Thread t2 = new BubbleSortThread(negArray);
t2.start();
out.println("Testing with negative numbers...");
try {
t2.join();
printArray(negArray, out);
} catch (InterruptedException ignored) { }
}
private void printArray(int[] a, PrintStream out) throws IOException {
for (int n : a) {
out.println(n);
}
out.println();
}
public void testQueue(PrintStream out) throws IOException {
BlockingQueue queue = new LinkedBlockingQueue(10);
Producer p = new Producer(queue, out);
Consumer c1 = new Consumer("Consumer 1", queue, out);
Consumer c2 = new Consumer("Consumer 2", queue, out);
Consumer c3 = new Consumer("Consumer 3", queue, out);
Consumer c4 = new Consumer("Consumer 4", queue, out);
p.start(); c1.start(); c2.start(); c3.start(); c4.start();
try {
MILLISECONDS.sleep(100);
} catch (InterruptedException ignored) { }
// Finish up with these threads
p.stop();
c1.stop(); c2.stop(); c3.stop(); c4.stop();
}
public void testCallable(PrintStream out) throws IOException {
ExecutorService service = Executors.newFixedThreadPool(5);
Future<BigInteger> prime1 = service.submit(new RandomPrimeSearch(512));
Future<BigInteger> prime2 = service.submit(new RandomPrimeSearch(512));
Future<BigInteger> prime3 = service.submit(new RandomPrimeSearch(512));
try {
BigInteger bigger = (prime1.get().multiply(prime2.get())).multiply(prime3.get());
out.println(bigger);
} catch (InterruptedException e) {
e.printStackTrace(out);
} catch (ExecutionException e) {
e.printStackTrace(out);
}
}
public static void main(String[] args) {
ThreadTester tester = new ThreadTester();
try {
tester.testBubbleSort(System.out);
tester.testQueue(System.out);
tester.testCallable(System.out);
} catch (Exception e) {
e.printStackTrace();
}
}
}
class BubbleSortThread extends Thread {
private int[] numbers;
public BubbleSortThread(int[] numbers) {
setName("Simple Thread");
setUncaughtExceptionHandler(
new SimpleThreadExceptionHandler());
this.numbers = numbers;
}
public void run() {
int index = numbers.length;
boolean finished = false;
while (!finished) {
index--;
finished = true;
for (int i=0; i<index; i++) {
// Create error condition
if (numbers[i+1] < 0) {
throw new IllegalArgumentException(
"Cannot pass negative numbers into this thread!");
}
if (numbers[i] > numbers[i+1]) {
// swap
int temp = numbers[i];
numbers[i] = numbers[i+1];
numbers[i+1] = temp;
finished = false;
}
}
}
}
}
class SimpleThreadExceptionHandler implements
Thread.UncaughtExceptionHandler {
public void uncaughtException(Thread t, Throwable e) {
System.err.printf("%s: %s at line %d of %s%n",
t.getName(),
e.toString(),
e.getStackTrace()[0].getLineNumber(),
e.getStackTrace()[0].getFileName());
}
}
class Consumer extends Thread {
private BlockingQueue q;
private PrintStream out;
public Consumer(String name, BlockingQueue q,
PrintStream out) {
setName(name);
this.q = q;
this.out = out;
}
public void run() {
try {
while (true) {
process(q.take());
}
} catch (InterruptedException e) {
out.printf("%s interrupted: %s", getName(), e.getMessage());
}
}
private void process(Object obj) {
out.printf("%s processing object:%n '%s'%n",
getName(), obj.toString());
}
}
class Producer extends Thread {
private BlockingQueue q;
private PrintStream out;
public Producer(BlockingQueue q, PrintStream out) {
setName("Producer");
this.q = q;
this.out = out;
}
public void run() {
try {
while (true) {
q.put(produce());
}
} catch (InterruptedException e) {
out.printf("%s interrupted: %s", getName(), e.getMessage());
}
}
private String produce() {
while (true) {
double r = Math.random();
// Only goes forward 1/10 of the time
if ((r*100) < 10) {
String s = String.format("Inserted at %tc", new Date());
return s;
}
}
}
}
class RandomPrimeSearch implements Callable<BigInteger> {
private static final Random prng = new SecureRandom();
private int bitSize;
public RandomPrimeSearch(int bitSize) {
this.bitSize = bitSize;
}
public BigInteger call() {
return BigInteger.probablePrime(bitSize, prng);
}
}
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