The application scenario and case analysis of the "Concurrent" framework in the Java class library
The application scenario and case analysis of the "Concurrent" framework in the Java class library
Introduction: In today's software development, handling multiple tasks in parallel is a common demand.In order to achieve efficient concurrency processing, Java provides a powerful concurrent programming framework- "Concurrent", which can help developers simplify the complexity of concurrent programming.This article will introduce the application scenarios of the "Concurrent" framework in the Java class library and some practical cases.
1. Application scenario
1. Parallel cycle: In some scenarios, the elements in a collection need to be processed parallel.The "Concurrent" framework in the Java class library provides Parallelstream parallel support, which can easily achieve parallel cycling.For example, for a list containing a large amount of integer, we can use the Foreach method of ParallelStream to implement parallel calculation.
List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
AtomicInteger sum = new AtomicInteger(0);
numbers.parallelStream()
.forEach(num -> sum.addAndGet(num));
System.out.println (sum.get ()); // Output 55, accumulation and
2. Thread security set: When multiple -threaded access access, the set of thread security needs to ensure the consistency and correctness of the data.The "Concurrent" framework in the Java class library provides some thread -safe set classes, such as ConcurrenThashmap and ConcurrentLinkedQueue.For example, using ConcurrenThashMap to store the counter sharing multiple threads.
ConcurrentHashMap<String, Integer> counter = new ConcurrentHashMap<>();
// thread 1, increase counter value
counter.compute("key1", (key, value) -> (value == null) ? 1 : value + 1);
// thread 2, increase counter value
counter.compute("key1", (key, value) -> (value == null) ? 1 : value + 1);
System.out.println (counter.get ("key1"); // Output 2, the counter increased twice by the counter
3. Thread pool: In high concurrency scenes, the creation and destruction of manual management threads is very cumbersome and easy to make mistakes.The "Concurrent" framework in the Java class library provides classes such as ExecutorService and ThreadPoolexecutor, which can easily create and manage thread pools to help achieve efficient concurrency processing.For example, create a fixed -size thread pool to handle multiple tasks at the same time.
ExecutorService executor = Executors.newFixedThreadPool(5);
for (int i = 0; i < 10; i++) {
final int taskId = i;
executor.execute(() -> {
System.out.println("Task " + taskId + " is processing.");
// Specific logic of executing tasks
});
}
executor.shutdown();
2. Case analysis
1. Parallel calculation PI value: The use of the "Concurrent" framework can easily implement parallel calculation of PI values.Below is a PI value calculation example based on the MONTE Carlo method.
int samplePoints = 1000000;
AtomicInteger insidePoints = new AtomicInteger(0);
IntStream.range(0, samplePoints)
.parallel()
.forEach(i -> {
double x = Math.random();
double y = Math.random();
if (x * x + y * y <= 1) {
insidePoints.incrementAndGet();
}
});
double pi = 4.0 * insidePoints.get() / samplePoints;
System.out.println("Calculated Pi: " + pi);
2. Parallel download file: Use the "Concurrent" framework to easily implement the concurrency download of the file.Below is an example of using a thread pool concurrent download file.
ExecutorService executor = Executors.newFixedThreadPool(5);
List<String> fileUrls = Arrays.asList("http://example.com/file1.txt",
"http://example.com/file2.txt",
"http://example.com/file3.txt",
"http://example.com/file4.txt",
"http://example.com/file5.txt");
for (String url : fileUrls) {
executor.execute(() -> {
System.out.println("Start downloading " + url);
// Execute file download logic
});
}
executor.shutdown();
Conclusion: The "CONCURRENT" framework in the Java class library provides developers with strong concurrent programming support, which can help simplify the complexity of concise concurrent processing.By reasonable application of the "Concurrent" framework, we can realize functions such as parallel computing, thread security set and thread pool, thereby improving the performance and reliability of the software.
references:
-JAVA official document: https://docs.oracle.com/en/java/javase/14/docs/api/index.html
