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📜  Java并发-AtomicBoolean类

📅  最后修改于: 2020-11-15 03:54:37             🧑  作者: Mango

java.util.concurrent.atomic.AtomicBoolean类提供了对基础布尔值的操作，这些值可以原子方式读写，并且还包含高级原子操作。 AtomicBoolean支持对基础布尔变量的原子操作。它具有get和set方法，它们的工作方式类似于对易失性变量的读写。也就是说，一个集合与该变量的任何后续get都具有事前发生的关系。原子compareAndSet方法还具有这些内存一致性功能。

原子布尔方法

以下是AtomicBoolean类中可用的重要方法的列表。

Sr.No. Method & Description
1

public boolean compareAndSet(boolean expect, boolean update)

Atomically sets the value to the given updated value if the current value == the expected value.
2

public boolean get()

Returns the current value.
3

public boolean getAndSet(boolean newValue)

Atomically sets to the given value and returns the previous value.
4

public void lazySet(boolean newValue)

Eventually sets to the given value.
5

public void set(boolean newValue)

Unconditionally sets to the given value.
6

public StringtoString()

Returns the String representation of the current value.
7

public boolean weakCompareAndSet(boolean expect, boolean update)

Atomically sets the value to the given updated value if the current value == the expected value.

例

以下TestThread程序显示了在基于线程的环境中AtomicBoolean变量的用法。

现场演示
import java.util.concurrent.atomic.AtomicBoolean;

public class TestThread {

   public static void main(final String[] arguments) throws InterruptedException {
      final AtomicBoolean atomicBoolean = new AtomicBoolean(false);

      new Thread("Thread 1") {

         public void run() {

            while(true) {
               System.out.println(Thread.currentThread().getName() 
                  +" Waiting for Thread 2 to set Atomic variable to true. Current value is "
                  + atomicBoolean.get());

               if(atomicBoolean.compareAndSet(true, false)) {
                  System.out.println("Done!");
                  break;
               }
            }
         };
      }.start();

      new Thread("Thread 2") {

         public void run() {
            System.out.println(Thread.currentThread().getName() +
               ", Atomic Variable: " +atomicBoolean.get()); 
            System.out.println(Thread.currentThread().getName() +
               " is setting the variable to true ");
            atomicBoolean.set(true);
            System.out.println(Thread.currentThread().getName() +
               ", Atomic Variable: " +atomicBoolean.get()); 
         };
      }.start();
   }
}

这将产生以下结果。

输出

Thread 1 Waiting for Thread 2 to set Atomic variable to true. Current value is false
Thread 1 Waiting for Thread 2 to set Atomic variable to true. Current value is false
Thread 1 Waiting for Thread 2 to set Atomic variable to true. Current value is false
Thread 2, Atomic Variable: false
Thread 1 Waiting for Thread 2 to set Atomic variable to true. Current value is false
Thread 2 is setting the variable to true
Thread 2, Atomic Variable: true
Thread 1 Waiting for Thread 2 to set Atomic variable to true. Current value is false
Done!