我有下一个代码：
public class App
{
public static void main( String[] args )
{
NewSmartThread n = new NewSmartThread("ST");
try{
n.join();
}catch(InterruptedException e){
System.out.println( "Умный поток был прерван" );
}
System.out.println( "Hello World!" );
}
}
class NewSimpleThread extends Thread {
public NewSimpleThread(String name){
super(name);
}
public void run(){
try {
for(int i =1; i<6; i++)
{
System.out.println("Thread " + this.getName() + " : " + i);
Thread.sleep(500);
}
} catch (InterruptedException e) {
System.out.println("Thread " + this.getName() + "был прерван.");
}
System.out.println("Thread " + this.getName() + " closed.");
}
}
class NewSmartThread extends Thread {
//final CountDownLatch start = new CountDownLatch(1);
//final CountDownLatch finish = new CountDownLatch(2);
public NewSmartThread(String name) {
super(name);
start();
}
public void run(){
//s1.split("(?<=\\G..)")
NewSimpleThread n1 = new NewSimpleThread("1");
NewSimpleThread n2 = new NewSimpleThread("2");
NewSimpleThread n3 = new NewSimpleThread("3");
n1.start();
n2.start();
n3.start();
try{
Thread.sleep(3000);
n1.join();
n2.join();
n3.join();
}catch(InterruptedException e){
System.out.println("Thread " + "broke.");
}
System.out.println("Smart thread " + this.getName() + " closed.");
}
}
我有下一个结果：
> Thread 2 : 1
> Thread 3 : 1
> Thread 1 : 1
> Thread 3 : 2
> Thread 1 : 2
> Thread 2 : 2
> Thread 2 : 3
> Thread 1 : 3
> Thread 3 : 3
> Thread 2 : 4
> Thread 1 : 4
> Thread 3 : 4
> Thread 1 : 5
> Thread 2 : 5
> Thread 3 : 5
> Thread 1 closed.
> Thread 2 closed.
> Thread 3 closed.
> Smart thread ST closed.
> Hello World!
但是如果我在下一个代码中使用block synchronized：
public class App
{
public static void main( String[] args )
{
NewSmartThread n = new NewSmartThread("ST");
try{
n.join();
}catch(InterruptedException e){
System.out.println( "Умный поток был прерван" );
}
System.out.println( "Hello World!" );
}
}
class NewSimpleThread extends Thread {
private static final Object monitor = new Object();
public NewSimpleThread(String name){
super(name);
}
public void run(){
synchronized (monitor) {
try {
monitor.wait();
for(int i =1; i<6; i++)
{
System.out.println("Thread " + this.getName() + " : " + i);
Thread.sleep(500);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("Thread " + this.getName() + " closed.");
}
}
public static void doNotifyAll(){
synchronized (monitor) {
monitor.notifyAll();
}
}
}
class NewSmartThread extends Thread {
public NewSmartThread(String name) {
super(name);
start();
}
public void run(){
NewSimpleThread n1 = new NewSimpleThread("1");
NewSimpleThread n2 = new NewSimpleThread("2");
NewSimpleThread n3 = new NewSimpleThread("3");
n1.start();
n2.start();
n3.start();
try{
Thread.sleep(3000);
NewSimpleThread.doNotifyAll();
n1.join();
n2.join();
n3.join();
}catch(InterruptedException e){
System.out.println("Thread " + "broke.");
}
System.out.println("Smart thread " + this.getName() + " closed.");
}
}
得到下一个结果：
Thread 3 : 1 Thread 3 : 2 Thread 3 : 3 Thread 3 : 4 Thread 3 : 5 Thread 3 closed. Thread 2 : 1 Thread 2 : 2 Thread 2 : 3 Thread 2 : 4 Thread 2 : 5 Thread 2 closed. Thread 1 : 1 Thread 1 : 2 Thread 1 : 3 Thread 1 : 4 Thread 1 : 5 Thread 1 closed. Smart thread ST closed. Hello World!
但我需要像第一个例子中那样的结果。并且不能使用像CountDownLatch这样的功能 - 只有同步块（这是实验室实验，这是一个要求）
有谁知道怎么做？
答案 0 :(得分：2)
如果我正确理解了这个问题，那么问题在于你在第二个例子中如何使用synchronized块。
你有synchronized整个逻辑，包括同步块内的for循环。虽然正确的方法是保持
synchronized(monitor){
monitor.wait(); //excluding exception handling
}
//for loop logic
因为你只是希望线程等待主线程的点头开始工作，一旦他们收到通知你不希望逻辑以synchronized的方式执行，所以释放显示器。因为在for循环时保持监视器，所以没有其他线程能够继续进行，直到持有它的那个完成。
答案 1 :(得分：0)
感谢Narendra Pathai。
我的代码的结束变体是下一个：
public class App
{
public static void main( String[] args )
{
NewSmartThread n = new NewSmartThread("ST");
try{
n.join();
}catch(InterruptedException e){
System.out.println( "Умный поток был прерван" );
}
System.out.println( "Hello World!" );
}
}
class NewSimpleThread extends Thread {
private static final Object monitor = new Object();
public NewSimpleThread(String name){
super(name);
}
public void run(){
try {
Latch.awaitZero();
for(int i =1; i<6; i++)
{
System.out.println("Thread " + this.getName() + " : " + i);
Thread.sleep(500);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("Thread " + this.getName() + " closed.");
}
public static void doNotifyAll(){
synchronized (monitor) {
monitor.notifyAll();
}
}
}
class NewSmartThread extends Thread {
public NewSmartThread(String name) {
super(name);
start();
}
public void run(){
NewSimpleThread n1 = new NewSimpleThread("1");
NewSimpleThread n2 = new NewSimpleThread("2");
NewSimpleThread n3 = new NewSimpleThread("3");
n1.start();
n2.start();
n3.start();
try{
Thread.sleep(3000);
Latch.doNotifyAll();
n1.join();
n2.join();
n3.join();
}catch(InterruptedException e){
System.out.println("Thread " + "broke.");
}
System.out.println("Smart thread " + this.getName() + " closed.");
}
}
class Latch {
private static final Object synchObj = new Object();
public static void awaitZero() throws InterruptedException {
synchronized (synchObj) {
synchObj.wait();
}
}
public static void doNotifyAll() {
synchronized (synchObj) {
synchObj.notifyAll();
}
}
}
我添加了课程：
class Latch {
private static final Object synchObj = new Object();
public static void awaitZero() throws InterruptedException {
synchronized (synchObj) {
synchObj.wait();
}
}
public static void doNotifyAll() {
synchronized (synchObj) {
synchObj.notifyAll();
}
}
}
代替
class NewSimpleThread extends Thread {
private static final Object monitor = new Object();