The purpose and function of the JSR 166 frame retrospective version in the Java class library
JSR 166 (Java Specification Request 166) is a standardized specification for concurrent tools in the Java library. It provides a series of tools for processing multi -threaded and concurrent programming.In the early version of Java, concurrent programming is not a task that is easy to achieve and control. Therefore, the emergence of JSR 166 fills the deficiencies of the Java class library in this regard, making concurrent programming simpler and efficient.
In the retrospective version of the JSR 166 framework, the following key components and functions mainly include:
1. Executor framework: Executor framework provides a thread pool to handle the execution and scheduling of tasks.Through this framework, the execution of the task can be decoupled from the creation and management of threads to better control the use of threads and resource scheduling.
Below is a simple Executor framework sample code:
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class ExecutorExample {
public static void main(String[] args) {
ExecutorService executor = Executors.newFixedThreadPool(5);
for (int i = 0; i < 10; i++) {
Runnable task = new Task(i);
executor.execute(task);
}
executor.shutdown();
}
}
class Task implements Runnable {
private int taskId;
public Task(int taskId) {
this.taskId = taskId;
}
@Override
public void run() {
System.out.println("Task " + taskId + " is executing.");
}
}
2. Parallel collection: The JSR 166 framework provides a series of threaded sets of safe set class, such as ConcurrenThashmap, ConcurrentlinkedQueue, etc.These concurrent sets use some efficient concurrency control technology to make the operation of the collection more efficient and secure in the multi -threaded environment.
The following is an example code using ConcurrenThashMap:
import java.util.concurrent.ConcurrentHashMap;
public class ConcurrentHashMapExample {
public static void main(String[] args) {
ConcurrentHashMap<String, Integer> map = new ConcurrentHashMap<>();
map.put("A", 1);
map.put("B", 2);
map.put("C", 3);
int value = map.get("B");
System.out.println("Value of key 'B' is " + value);
}
}
3. Synchronous tool class: The JSR 166 framework also provides some synchronous tool classes, such as Countdownlatch, SEMAPHORE, CyclicBarrier, etc.These tools can help us better control the execution order and collaboration of threads, making the task scheduling in the multi -threaded environment simpler and reliable.
Below is an example code using countdownlatch:
import java.util.concurrent.CountDownLatch;
public class CountDownLatchExample {
public static void main(String[] args) {
final int NUM_THREADS = 5;
final CountDownLatch startSignal = new CountDownLatch(1);
final CountDownLatch doneSignal = new CountDownLatch(NUM_THREADS);
for (int i = 0; i < NUM_THREADS; i++) {
Thread thread = new Thread(() -> {
try {
startSignal.await();
System.out.println("Thread " + Thread.currentThread().getId() + " is executing.");
doneSignal.countDown();
} catch (InterruptedException e) {
e.printStackTrace();
}
});
thread.start();
}
System.out.println("Waiting for threads to start.");
startSignal.countDown();
try {
doneSignal.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("All threads have finished executing.");
}
}
The retrospective version of the JSR 166 framework provides a reliable and efficient solution for Java concurrent programming, making the task scheduling and concurrency operation in the multi -threaded environment easier and easier.
