要实现并发哈希映射的线程安全性和发生顺序关系,可以使用以下方法:
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
public class ConcurrentHashMapExample {
public static void main(String[] args) {
Map concurrentHashMap = new ConcurrentHashMap<>();
// 同时启动多个线程来操作并发哈希映射
Runnable task = () -> {
for (int i = 0; i < 100; i++) {
concurrentHashMap.put(Thread.currentThread().getName() + "-" + i, "value");
}
};
// 创建并启动多个线程
Thread thread1 = new Thread(task);
Thread thread2 = new Thread(task);
thread1.start();
thread2.start();
// 等待线程执行完毕
try {
thread1.join();
thread2.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
// 打印并发哈希映射的内容
for (String key : concurrentHashMap.keySet()) {
System.out.println(key + ": " + concurrentHashMap.get(key));
}
}
}
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class ConcurrentHashmapWithLockExample {
private final Lock lock = new ReentrantLock();
private final Map hashMap = new HashMap<>();
private final Condition condition = lock.newCondition();
public void put(String key, String value) {
lock.lock();
try {
hashMap.put(key, value);
condition.signalAll(); // 通知其他等待线程
} finally {
lock.unlock();
}
}
public String get(String key) {
lock.lock();
try {
while (!hashMap.containsKey(key)) {
condition.await(); // 等待key被放入映射中
}
return hashMap.get(key);
} catch (InterruptedException e) {
e.printStackTrace();
return null;
} finally {
lock.unlock();
}
}
public static void main(String[] args) {
ConcurrentHashmapWithLockExample concurrentHashmap = new ConcurrentHashmapWithLockExample();
// 同时启动多个线程来操作并发哈希映射
Runnable task = () -> {
for (int i = 0; i < 100; i++) {
concurrentHashmap.put(Thread.currentThread().getName() + "-" + i, "value");
}
};
// 创建并启动多个线程
Thread thread1 = new Thread(task);
Thread thread2 = new Thread(task);
thread1.start();
thread2.start();
// 等待线程执行完毕
try {
thread1.join();
thread2.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
// 打印并发哈希映射的内容
for (String key : concurrentHashmap.hashMap.keySet()) {
System.out.println(key + ": " + concurrentHashmap.get(key));
}
}
}
以上示例代码展示了使用同步容器类和显式锁来实现并发哈希映射的线程安全性和发生顺序关系的解决方法。
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