如何让 AtomicInteger 在 Runnable 类中工作

Question

我用Java编写了这段代码作为Runnable，但我的教授希望我添加AtomicInteger，这样就不会有线程干扰。我该怎么做呢？我尝试查找如何在代码中使用它的示例，但我不知道在这种情况下该怎么做。

public class GarageWorker {
public static void main(String[] args) {
System.out.println("We are going to count the vehicles in the garage");
System.out.println();
System.out.println("There are 50 vehicles in the garage to start with!");
System.out.println();
GarageWorker garage = new GarageWorker(50);
Runnable vehicleEnter = garage.new Enter();
Runnable vehicleExit = garage.new Exit();
Thread thread1 = new Thread(vehicleEnter);
Thread thread2 = new Thread(vehicleExit);
thread1.start();
thread2.start();
}
public GarageWorker(int initialCarCount) {
counter = initialCarCount;
}
public int counter;
public class Enter implements Runnable {
public Enter() {
}
public int increaseVehicleCount() {
return ++counter;
}
public void run() {
while (counter < 100) {
System.out.println("One vehicle entered the garage now there are " + increaseVehicleCount());
}
}
}
public class Exit implements Runnable {
public Exit() {
}
public int decreaseVehicleCount() {
return --counter;
}
public void run() {
while (counter > 0) {
System.out.println("One vehicle left the garage now there are " + decreaseVehicleCount());
}
}
}
}

代码运行良好，但我的教授希望我将AtomicInteger类实现到代码中。

Answer 1

我假设你的教授希望你把counter改成AtomicInteger。首先，您要导入AtomicInteger并更改counter声明和构造函数以反映这一点。

import java.util.concurrent.atomic.AtomicInteger;

public GarageWorker(int initialCarCount) {
counter = new AtomicInteger(initialCarCount);
}
public AtomicInteger counter;

此外，您希望更改increaseVehicleCount和decreaseVehicleCount方法，以便使用AtomicInteger而不是int。

public int increaseVehicleCount() {
return counter.incrementAndGet();
}

public int decreaseVehicleCount() {
return counter.decrementAndGet();
}

incrementAndGet和decrementAndGet就像他们所说的那样：它们递增(或递减(，随后返回新值。有关更多信息，请查看 Javadoc。

干杯！