Multi -threaded programming guide in Java core framework
Multi -threaded programming guide in Java core framework
Multi -threaded programming is very important in the Java core framework.Multi -threading can perform multiple tasks at the same time to improve the performance and efficiency of the program.However, multi -threaded programming will also bring some challenges, such as thread security, dead locks, live locks and other issues.This article will introduce the guidelines for multi -thread programming in the core framework of the Java and provide some example code.
1. The method of creating a thread in Java
Java provides two methods to create threads: inherit the Thread class and implement the Runnable interface.Inheriting the Thread class requires rewriting the run () method, and the Runnable interface needs to implement the RUN () method.The following is a sample code for two methods:
Inherit the example code of Thread class:
class MyThread extends Thread {
public void run() {
// The execution logic of the thread
}
}
public class Main {
public static void main(String args[]) {
MyThread thread = new MyThread();
thread.start();
}
}
Example code to implement the Runnable interface:
class MyRunnable implements Runnable {
public void run() {
// The execution logic of the thread
}
}
public class Main {
public static void main(String args[]) {
Thread thread = new Thread(new MyRunnable());
thread.start();
}
}
2. thread security
In a multi -threaded environment, multiple threads may access and modify the shared data at the same time, which can easily lead to data inconsistent problems.In order to achieve thread security, the synchronized keyword or LOCK interface can be used to synchronize the key code block or method.The following is a sample code that uses synchronized to implement thread security:
class Counter {
private int count = 0;
public synchronized void increment() {
count++;
}
public synchronized int getCount() {
return count;
}
}
public class Main {
public static void main(String args[]) {
Counter counter = new Counter();
Thread thread1 = new Thread(() -> {
for (int i = 0; i < 1000; i++) {
counter.increment();
}
});
Thread thread2 = new Thread(() -> {
for (int i = 0; i < 1000; i++) {
counter.increment();
}
});
thread1.start();
thread2.start();
try {
thread1.join();
thread2.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println (counter.getCount ()); // The output result is 2000 as 2000
}
}
3. Dead lock and live lock
Dead locks and live locks are common problems in multi -threaded programming.Dead lock finger two or more threads wait for the other party to release the resources with each other, so that the program cannot continue to execute.The live lock finger thread constantly modify its own state to avoid dead locks, but it cannot continue to be executed.In order to avoid dead and alive locks, the logic of multi -threaded synchronization should be designed reasonably, and the strategy of "avoiding, detecting and lifting" strategies should be used.
The following is a dead lock sample code:
class Deadlock {
private final Object lock1 = new Object();
private final Object lock2 = new Object();
public void method1() {
synchronized (lock1) {
synchronized (lock2) {
// Execute operations
}
}
}
public void method2() {
synchronized (lock2) {
synchronized (lock1) {
// Execute operations
}
}
}
}
In order to avoid dead locks, you can adjust the order order or use the Thread.sleep () and other methods to increase the interval between threads.
The above is some guidelines and example code of multi -threaded programming in the core framework of Java.I hope this article will help you understand and use multi -threaded programming.
