AtomicInteger的实际用法

本文介绍了AtomicInteger的实际用法的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

作为支持指令（ compareAndSet（））来实现非阻塞算法。

下面是：

  public class AtomicPseudoRandom extends PseudoRandom {
 private AtomicInteger seed; 
 AtomicPseudoRandom（int seed）{
 this.seed = new AtomicInteger（seed）; 
} 
 
 public int nextInt（int n）{
 while（true）{
 int s = seed.get（）; 
 int nextSeed = calculateNext（s）; 
 if（seed.compareAndSet（s，nextSeed））{
 int remainder = s％n; 
 return remaining> 0？余数：余数+ n; 
} 
} 
} 
 ... 
} 
  

b $ b

可以看到，它基本上与 incrementAndGet（）几乎相同，但执行任意计算（ calculateNext

I sort of understand that AtomicInteger and other Atomic variables allow concurrent accesses. In what cases is this class typically used though?

解决方案

There are two main uses of AtomicInteger:

• As an atomic counter (incrementAndGet(), etc) that can be used by many threads concurrently

• As a primitive that supports compare-and-swap instruction (compareAndSet()) to implement non-blocking algorithms.

  Here is an example of non-blocking random number generator from Brian Göetz's Java Concurrency In Practice:

  public class AtomicPseudoRandom extends PseudoRandom {
      private AtomicInteger seed;
      AtomicPseudoRandom(int seed) {
          this.seed = new AtomicInteger(seed);
      }
  
      public int nextInt(int n) {
          while (true) {
              int s = seed.get();
              int nextSeed = calculateNext(s);
              if (seed.compareAndSet(s, nextSeed)) {
                  int remainder = s % n;
                  return remainder > 0 ? remainder : remainder + n;
              }
          }
      }
      ...
  }
  

  As you can see, it basically works almost the same way as incrementAndGet(), but performs arbitrary calculation (calculateNext()) instead of increment (and processes the result before return).

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