Pattern: Wait outside of while loop
Issue: -
Calls to Object.wait() must be within a while loop. This ensures that the awaited condition has not already been satisfied by another thread before the wait() is invoked. It also ensures that the proper thread was resumed and guards against incorrect notification.
As a more modern and flexible alternative, consider using the Java concurrency utilities instead of wait() and notify().
Example of violation:
class SomeClass {
private data
void processData()
synchronized(data) {
if (!data.isReady()) {
data.wait()
}
data.calculateStatistics()
}
}
}Example of correct usage:
class SomeClass {
private data
void processData()
synchronized(data) {
while (!data.isReady()) {
data.wait()
}
data.calculateStatistics()
}
}
}