"volatile" variables should not be used with compound operators

Using compound operators as well as increments and decrements (and toggling, in the case of boolean}}s) on primitive fields are not atomic operations. That is, they don't happen in a single step. For instance, when a {{volatile primitive field is incremented or decremented you run the risk of data loss if threads interleave in the steps of the update. Instead, use a guaranteed-atomic class such as AtomicInteger, or synchronize the access.

Noncompliant Code Example

private volatile int count = 0;
private volatile boolean boo = false;

public void incrementCount() {
  count++;  // Noncompliant
}

public void toggleBoo(){
  boo = !boo;  // Noncompliant
}

Compliant Solution

private AtomicInteger count = 0;
private boolean boo = false;

public void incrementCount() {
  count.incrementAndGet(); 
}

public synchronized void toggleBoo() {
  boo = !boo;
}

See

• CERT, VNA02-J. - Ensure that compound operations on shared variables are atomic