我写了这个程序来寻找一个新号码。问题是我的程序没有停止。我知道我必须用线程做点什么，但我不知道。
Primes class（main）：
public class Primes {
/**
* The queue holding candidates we want to check for primality.
*/
private BlockingQueue<Integer> candidateQueue;
/**
* The queue holding primes we want to print before inserting into the result set.
*/
private BlockingQueue<Integer> primesQueue;
/**
* The set holding the numbers that we have determined are prime.
*/
private Set<Integer> primeNumbers;
/**
* Create a new instance of the Primes checker program.
*/
public Primes() {
// TODO: If this the best type of BlockingQueue to use, and is this the best size?
// Feel free to change both.
candidateQueue = new LinkedBlockingQueue<Integer>();
// TODO: If this the best type of BlockingQueue to use, and is this the best size?
// Feel free to change both.
primesQueue = new LinkedBlockingQueue<Integer>();
// TODO: Is a HashSet the best option here, and are there any options that would
// help make it perform better? Feel free to change to a different type of Set or
// to add parameters to the constructor.
primeNumbers = new HashSet<Integer>();
}
/**
* Actually run the primes finder, looking for primes between smallest and biggest (inclusive).
*
* @param smallest the smallest number to check
* @param biggest the biggest number to check
*
* @return a {@link Set} containing the prime numbers we have found
*/
public Set<Integer> findPrimesInRange(int smallest, int biggest) {
// TODO: You should create the number generator and primes printer, as well
// as some number of primality checkers. You should create these all as
// threads that you can run to look for prime numbers. You should have at least
// two instances of {@link PrimalityChecker}, but could have more if this makes
// your program faster.
// TODO: This is just here to make the compiler happy, you should return something real...
NumberGenerator a = new NumberGenerator( smallest,biggest,candidateQueue);
new Thread(a).start();
PrimalityChecker p1 = new PrimalityChecker(candidateQueue,primesQueue);
new Thread(p1).start();
PrimalityChecker p2 = new PrimalityChecker(candidateQueue,primesQueue);
new Thread(p2).start();
PrimesPrinter pp = new PrimesPrinter(primesQueue,primeNumbers);
Thread t1= new Thread(pp);
t1.start();
// t1.interrupt();
return primeNumbers;
}
public static void main(String[] args) {
Primes p = new Primes();
// Remember, 1 is not prime! http://en.wikipedia.org/wiki/Prime_number
p.findPrimesInRange(2, 100);
}
}
NumberGenerator上课：
public class NumberGenerator implements Runnable {
/** The biggest number we plan to check */
private final int biggestNumberToCheck;
/** A queue where we will place the numbers that we generate, which need to be checked */
private final BlockingQueue<Integer> candidateQueue;
private final int smallestNumberStart;
// TODO: What other state do we need?
/**
* Create a new instance of the NumberGenerator class, which will hand out numbers
* that need to be checked.
*
* @param smallest the smallest number to check
* @param biggest the biggest number to check
* @param queue the queue that we will put numbers to check into
*/
public NumberGenerator(int smallest, int biggest, BlockingQueue<Integer> queue) {
biggestNumberToCheck = biggest;
candidateQueue = queue;
smallestNumberStart = smallest;
}
public void run(){
for(int i=smallestNumberStart; i<=biggestNumberToCheck; i++){
//int rand= ThreadLocalRandom.current().nextInt(smallestNumberStart, biggestNumberToCheck);
candidateQueue.add(i);
}
}
// TODO: You can decide how you want to turn this into something runnable as a thread.
// Please look at the code examples we've discussed in class and at the lecture slides,
// as well as at the Concurrency tutorial: http://docs.oracle.com/javase/tutorial/essential/concurrency/
}
PrimalityChecker：
public class PrimalityChecker implements Runnable {
/** A queue that holds generated numbers that we have not yet checked */
private final BlockingQueue<Integer> candidateQueue;
/** A queue where we place numbers when we determine they are prime */
private final BlockingQueue<Integer> primesQueue;
// TODO: What other state do we need?
/**
* Create an instance of the PrimalityChecker class, which will check numbers to see if
* they are prime and then insert them into a result queue.
*
* @param candidates queue that holds the candidates to check
* @param primes queue that holds prime numbers we have found
*/
public PrimalityChecker(BlockingQueue<Integer> candidates, BlockingQueue<Integer> primes) {
candidateQueue = candidates;
primesQueue = primes;
}
public void run(){
Iterator<Integer> itr = candidateQueue.iterator();
while(itr.hasNext()){
Integer Queue = null;
try {
Queue = candidateQueue.take();
} catch (InterruptedException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
if (isPrime(Queue))
{
primesQueue.add(Queue);
// try {
// System.out.println(primesQueue.take());
// } catch (InterruptedException e) {
// TODO Auto-generated catch block
// e.printStackTrace();
//}
}
}
//catch (InterruptedException e) {
// TODO Auto-generated catch block
// e.printStackTrace();
//}
//
}
public static boolean isPrime(int number){
for(int i=2; i<number; i++){
if(number%i == 0){
return false;
}
}
return true;
}
// TODO: You can decide how you want to turn this into something runnable as a thread.
// Please look at the code examples we've discussed in class and at the lecture slides,
// as well as at the Concurrency tutorial: http://docs.oracle.com/javase/tutorial/essential/concurrency/
}
PrimePrinter：
public class PrimesPrinter implements Runnable {
/** A queue that holds numbers we have determined to be prime but have not yet processed */
private final BlockingQueue<Integer> primesQueue;
/** A set that holds all the prime numbers we have found */
private final Set<Integer> primesSet;
// TODO: What other state do we need?
/**
* Create an instance of the PrimesPrinter class, which will print any numbers that
* come in on the primes queue and then place them in the primes set.
*
* @param primes queue that holds prime numbers we have found but not yet processed
* @param primesSet set that holds all the prime numbers we have found
*/
public PrimesPrinter(BlockingQueue<Integer> primes, Set<Integer> primesSet) {
primesQueue = primes;
this.primesSet = primesSet;
}
@Override
public void run() {
// Iterator<Integer> itr = primesQueue.iterator();
// while (!Thread.currentThread().isInterrupted()){
while(primesQueue.size()>=0){
Integer Queue;
try {
Queue=primesQueue.take();
//Queue = primesQueue.poll(100, TimeUnit.MILLISECONDS);
//if(Queue==null){
// break;
//}
System.out.println(Queue);
primesSet.add(Queue);
}
catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
答案 0 :(得分：3)
只要至少有一个非守护程序线程处于活动状态，JVM就不会终止。
所以基本上你有两个选项，一个是mark your processing thread as daemon，所以它不会让Java退出。另一个选择是你实现某种信号机制，这样一个主线程可以在其工作结束时发出所有其他信号停止信号。
在这两种情况下，您都需要确定待处理的工作是否要阻止您的关闭。在您将处理嵌套到各种线程的情况下，您可能希望在排队特殊的“shutdown”元素时使所有队列处理线程终止（保留run()方法）。
// this is how you start a runable with a daemon thread
Thread t1 = new Thread(r1);
t1.setDaemon(true);
t1.start();
这是一个允许停止的示例（不完整）可运行：
public class PrimesPrinter implements Runnable {
public static final Integer LAST = new Integer(0); // values doesnt matter
private final BlockingQueue<Integer> primesQueue;
private int lastCount = 0;
public void run() {
while (true) {
Integer i = primesQueue.take(); // blocks
if (i == LAST) {
lastCount++; // wait for 2 checkers
if (lastCount == 2)
return;
else
continue; // next might be last or other result
}
System.out.println(i);
}
}
}
和
public class PrimalityChecker implements Runnable {
public static final Integer LAST = new Integer(42);
public void run() {
while (true) {
Integer i = candidateQueue.take();
if (i == PrimalityChecker.LAST) break;
if (isPrime(Queue))
primesQueue.add(Queue);
}
primesQueue.add(PrimesPrinter.LAST);
}
}
这就是你如何使初始线程将足够的LAST元素排入队列以便工作者终止：
public NumberGenerator(int smallest, int biggest, BlockingQueue<Integer> queue) {
public void run(){
for(int i=smallestNumberStart; i<=biggestNumberToCheck; i++){
candidateQueue.add(i);
}
candidateQueue.add(PrimalityChecker.LAST);
candidateQueue.add(PrimalityChecker.LAST);
}
}
这当然要求生产者线程NumberGenerator向候选队列添加LAST元素，候选队列将最后一个元素添加到primesQueue，依此类推。
答案 1 :(得分：0)
正如@Eckes所建议的，要发出其他线程停止的信号。您可以检查candidateQueue和primesQueue的大小，并中断正在运行的线程并退出程序。 我做了一些代码更改，现在程序正在退出。如果这有帮助，请告诉我。
import java.util.concurrent.BlockingQueue;
public class NumberGenerator implements Runnable {
/** The biggest number we plan to check */
private final int biggestNumberToCheck;
/** A queue where we will place the numbers that we generate, which need to be checked */
private final BlockingQueue<Integer> candidateQueue;
private final int smallestNumberStart;
// TODO: What other state do we need?
/**
* Create a new instance of the NumberGenerator class, which will hand out numbers
* that need to be checked.
*
* @param smallest the smallest number to check
* @param biggest the biggest number to check
* @param queue the queue that we will put numbers to check into
*/
public NumberGenerator(int smallest, int biggest, BlockingQueue<Integer> queue) {
biggestNumberToCheck = biggest;
candidateQueue = queue;
smallestNumberStart = smallest;
}
public void run(){
for(int i=smallestNumberStart; i<=biggestNumberToCheck; i++){
//int rand= ThreadLocalRandom.current().nextInt(smallestNumberStart, biggestNumberToCheck);
candidateQueue.add(i);
}
}
// TODO: You can decide how you want to turn this into something runnable as a thread.
// Please look at the code examples we've discussed in class and at the lecture slides,
// as well as at the Concurrency tutorial: http://docs.oracle.com/javase/tutorial/essential/concurrency/
}
import java.util.Iterator;
import java.util.concurrent.BlockingQueue;
public class PrimalityChecker implements Runnable {
/** A queue that holds generated numbers that we have not yet checked */
private final BlockingQueue<Integer> candidateQueue;
/** A queue where we place numbers when we determine they are prime */
private final BlockingQueue<Integer> primesQueue;
// TODO: What other state do we need?
/**
* Create an instance of the PrimalityChecker class, which will check numbers to see if
* they are prime and then insert them into a result queue.
*
* @param candidates queue that holds the candidates to check
* @param primes queue that holds prime numbers we have found
*/
public PrimalityChecker(BlockingQueue<Integer> candidates, BlockingQueue<Integer> primes) {
candidateQueue = candidates;
primesQueue = primes;
}
public void run() {
Iterator<Integer> itr = candidateQueue.iterator();
while (itr.hasNext()) {
Integer Queue = null;
try {
Queue = candidateQueue.take();
} catch (InterruptedException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
return;
}
if (isPrime(Queue)) {
primesQueue.add(Queue);
// try {
// System.out.println(primesQueue.take());
// } catch (InterruptedException e) {
// TODO Auto-generated catch block
// e.printStackTrace();
// }
}
}
// catch (InterruptedException e) {
// TODO Auto-generated catch block
// e.printStackTrace();
// }
//
}
public static boolean isPrime(int number){
for(int i=2; i<number; i++){
if(number%i == 0){
return false;
}
}
return true;
}
// TODO: You can decide how you want to turn this into something runnable as a thread.
// Please look at the code examples we've discussed in class and at the lecture slides,
// as well as at the Concurrency tutorial: http://docs.oracle.com/javase/tutorial/essential/concurrency/
}
import java.util.Set;
import java.util.concurrent.BlockingQueue;
public class PrimesPrinter implements Runnable {
/** A queue that holds numbers we have determined to be prime but have not yet processed */
private final BlockingQueue<Integer> primesQueue;
/** A set that holds all the prime numbers we have found */
private final Set<Integer> primesSet;
// TODO: What other state do we need?
/**
* Create an instance of the PrimesPrinter class, which will print any numbers that
* come in on the primes queue and then place them in the primes set.
*
* @param primes queue that holds prime numbers we have found but not yet processed
* @param primesSet set that holds all the prime numbers we have found
*/
public PrimesPrinter(BlockingQueue<Integer> primes, Set<Integer> primesSet) {
primesQueue = primes;
this.primesSet = primesSet;
}
@Override
public void run() {
// Iterator<Integer> itr = primesQueue.iterator();
while (!Thread.currentThread().isInterrupted()) {
while (primesQueue.size() > 0) {
Integer Queue;
try {
Queue = primesQueue.take();
// Queue = primesQueue.poll(100, TimeUnit.MILLISECONDS);
// if(Queue==null){
// break;
// }
System.out.println(Queue);
primesSet.add(Queue);
}
catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
public class Primes {
/**
* The queue holding candidates we want to check for primality.
*/
private BlockingQueue<Integer> candidateQueue;
/**
* The queue holding primes we want to print before inserting into the result set.
*/
private BlockingQueue<Integer> primesQueue;
/**
* The set holding the numbers that we have determined are prime.
*/
private Set<Integer> primeNumbers;
/**
* Create a new instance of the Primes checker program.
*/
public Primes() {
// TODO: If this the best type of BlockingQueue to use, and is this the best size?
// Feel free to change both.
candidateQueue = new LinkedBlockingQueue<Integer>();
// TODO: If this the best type of BlockingQueue to use, and is this the best size?
// Feel free to change both.
primesQueue = new LinkedBlockingQueue<Integer>();
// TODO: Is a HashSet the best option here, and are there any options that would
// help make it perform better? Feel free to change to a different type of Set or
// to add parameters to the constructor.
primeNumbers = new HashSet<Integer>();
}
/**
* Actually run the primes finder, looking for primes between smallest and biggest (inclusive).
*
* @param smallest the smallest number to check
* @param biggest the biggest number to check
*/
public void findPrimesInRange(int smallest, int biggest) {
// TODO: You should create the number generator and primes printer, as well
// as some number of primality checkers. You should create these all as
// threads that you can run to look for prime numbers. You should have at least
// two instances of {@link PrimalityChecker}, but could have more if this makes
// your program faster.
// TODO: This is just here to make the compiler happy, you should return something real...
NumberGenerator a = new NumberGenerator( smallest,biggest,candidateQueue);
Thread threadA= new Thread(a);
threadA.start();
PrimalityChecker p1 = new PrimalityChecker(candidateQueue,primesQueue);
Thread threadP1= new Thread(p1);
threadP1.start();
PrimalityChecker p2 = new PrimalityChecker(candidateQueue,primesQueue);
Thread threadP2= new Thread(p2);
threadP2.start();
PrimesPrinter pp = new PrimesPrinter(primesQueue,primeNumbers);
Thread threadPP= new Thread(pp);
threadPP.start();
while(true){
try {
Thread.sleep(1000);
if(candidateQueue.size() == 0 && primesQueue.size() ==0){
threadA.interrupt();
threadP1.interrupt();
threadP2.interrupt();
threadPP.interrupt();
break;
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
// t1.interrupt();
//System.out.println("T");
}
public static void main(String[] args) {
Primes p = new Primes();
// Remember, 1 is not prime! http://en.wikipedia.org/wiki/Prime_number
p.findPrimesInRange(2, 100);
}
}
答案 2 :(得分：0)
以下是更新的代码，如果有帮助请告诉我。
import java.util.concurrent.BlockingQueue;
public class NumberGenerator implements Runnable {
private final int biggestNumberToCheck;
private final BlockingQueue<Integer> candidateQueue;
private final int smallestNumberStart;
public NumberGenerator(int smallest, int biggest,
BlockingQueue<Integer> queue) {
biggestNumberToCheck = biggest;
candidateQueue = queue;
smallestNumberStart = smallest;
}
public void run() {
for (int i = smallestNumberStart; i <= biggestNumberToCheck; i++) {
candidateQueue.add(i);
}
}
}
PrimalityChecker
import java.util.Iterator;
import java.util.concurrent.BlockingQueue;
public class PrimalityChecker implements Runnable {
private final BlockingQueue<Integer> candidateQueue;
private final BlockingQueue<Integer> primesQueue;
public PrimalityChecker(BlockingQueue<Integer> candidates,
BlockingQueue<Integer> primes) {
candidateQueue = candidates;
primesQueue = primes;
}
public void run() {
Iterator<Integer> itr = candidateQueue.iterator();
while (itr.hasNext()) {
Integer Queue = null;
try {
Queue = candidateQueue.take();
} catch (InterruptedException e1) {
System.out.println("PrimalityChecker Thread interruped");
return;
}
if (isPrime(Queue)) {
primesQueue.add(Queue);
}
}
}
public static boolean isPrime(int number) {
for (int i = 2; i < number; i++) {
if (number % i == 0) {
return false;
}
}
return true;
}
}
PrimesPrinter
import java.util.Set;
import java.util.concurrent.BlockingQueue;
public class PrimesPrinter implements Runnable {
private final BlockingQueue<Integer> primesQueue;
private final Set<Integer> primesSet;
public PrimesPrinter(BlockingQueue<Integer> primes, Set<Integer> primesSet) {
primesQueue = primes;
this.primesSet = primesSet;
}
@Override
public void run() {
while (!Thread.currentThread().isInterrupted()) {
while (primesQueue.size() > 0) {
Integer Queue;
try {
Queue = primesQueue.take();
System.out.println(Queue);
primesSet.add(Queue);
}
catch (InterruptedException e) {
System.out.println("Primes Printer Interrupted");
e.printStackTrace();
}
}
}
}
}
素数
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
public class Primes {
private BlockingQueue<Integer> candidateQueue;
private BlockingQueue<Integer> primesQueue;
private Set<Integer> primeNumbers;
public Primes() {
candidateQueue = new LinkedBlockingQueue<Integer>();
primesQueue = new LinkedBlockingQueue<Integer>();
primeNumbers = new HashSet<Integer>();
}
public void findPrimesInRange(int smallest, int biggest) {
NumberGenerator a = new NumberGenerator(smallest, biggest,
candidateQueue);
Thread threadA = new Thread(a);
threadA.start();
PrimalityChecker p1 = new PrimalityChecker(candidateQueue, primesQueue);
Thread threadP1 = new Thread(p1);
threadP1.start();
PrimalityChecker p2 = new PrimalityChecker(candidateQueue, primesQueue);
Thread threadP2 = new Thread(p2);
threadP2.start();
PrimesPrinter pp = new PrimesPrinter(primesQueue, primeNumbers);
Thread threadPP = new Thread(pp);
threadPP.start();
while (true) {
try {
Thread.sleep(1000);
if (candidateQueue.size() == 0 && primesQueue.size() == 0) {
threadA.interrupt();
threadP1.interrupt();
threadP2.interrupt();
threadPP.interrupt();
break;
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
Primes p = new Primes();
p.findPrimesInRange(2, 100);
}
}