Threading and concurrent programming in the "core" framework of Java class libraries refer to
Guidelines for Threading and Concurrent Programming in the "Core" Framework of Java Class Libraries
Introduction
Java is a widely used programming language with rich class libraries and frameworks, including powerful threading and concurrent programming support. This article will introduce threading and concurrent programming in the "core" framework of Java class libraries, aiming to help developers leverage Java's powerful capabilities to write efficient and scalable concurrent applications.
1、 Thread Model
Java uses a thread based concurrency model, where each thread is an independent execution unit. Threads can execute multiple tasks simultaneously, achieving parallel processing of multiple tasks. In Java, threads are supported by the Thread class and the Runnable interface.
Example code:
class MyRunnable implements Runnable {
public void run() {
//Code executed by threads
}
}
public class MyThreadDemo {
public static void main(String[] args) {
MyRunnable myRunnable = new MyRunnable();
Thread myThread = new Thread(myRunnable);
myThread.start();
}
}
2、 Thread lifecycle
Threads have different lifecycle stages in Java, including creation, running, blocking, and termination. Understanding the lifecycle of threads is crucial for writing concurrent programs.
Example code:
class MyRunnable implements Runnable {
public void run() {
System. out. println ("thread execution in progress");
}
}
public class ThreadLifecycleDemo {
public static void main(String[] args) {
MyRunnable myRunnable = new MyRunnable();
Thread myThread = new Thread(myRunnable);
System. out. println ("Thread State:"+myThread. getState())// Print Thread Status
myThread.start();
System. out. println ("Thread State:"+myThread. getState())// Print Thread Status
//Terminate Thread
try {
Thread. sleep (1000)// Let the main thread sleep for 1 second
} catch (InterruptedException e) {
e.printStackTrace();
}
System. out. println ("Thread State:"+myThread. getState())// Print Thread Status
}
}
3、 Thread synchronization
In concurrent programming, thread synchronization is a key technique used to ensure correct interaction between multiple threads. Java provides multiple mechanisms to achieve thread synchronization, including the synchronized keyword, Lock interface, and Condition interface.
Example code:
class Counter {
private int count = 0;
private Object lock = new Object();
public void increment() {
synchronized (lock) {
count++;
}
}
public void decrement() {
synchronized (lock) {
count--;
}
}
public int getCount() {
synchronized (lock) {
return count;
}
}
}
public class ThreadSyncDemo {
public static void main(String[] args) {
Counter counter = new Counter();
//Create and start multiple threads
for (int i = 0; i < 10; i++) {
new Thread(() -> {
counter.increment();
counter.decrement();
System.out.println("Count: " + counter.getCount());
}).start();
}
}
}
4、 Inter thread communication
It is common for multiple threads to require data sharing and communication. Java provides waiting, notification, and wake-up mechanisms for objects to achieve communication between threads.
Example code:
class Message {
private String content;
private boolean empty = true;
public synchronized String read() {
while (empty) {
try {
Wait()// Wait until the message is not empty
} catch (InterruptedException e) {
e.printStackTrace();
}
}
empty = true;
NotifyAll()// Wake up other waiting threads
return content;
}
public synchronized void write(String content) {
while (!empty) {
try {
Wait()// Wait until the message is empty
} catch (InterruptedException e) {
e.printStackTrace();
}
}
empty = false;
this.content = content;
NotifyAll()// Wake up other waiting threads
}
}
public class ThreadCommunicationDemo {
public static void main(String[] args) {
Message message = new Message();
//Create and start multiple read threads
for (int i = 0; i < 5; i++) {
new Thread(() -> {
String content = message.read();
System.out.println("Read: " + content);
}).start();
}
//Create and start multiple write threads
for (int i = 0; i < 5; i++) {
new Thread(() -> {
message.write("Hello World");
System.out.println("Write: " + "Hello World");
}).start();
}
}
}
summary
This article introduces threading and concurrent programming in the "core" framework of Java class libraries. We learned about the concepts and usage of thread models, thread lifecycles, thread synchronization, and inter thread communication, and demonstrated their specific applications through example code. By utilizing the functions provided by the Java class library in a reasonable manner, we can write efficient and scalable concurrent applications.
