In single-threaded environments, the use of this in constructors is normal, and expected. But in multi-threaded environments, it could
expose partially-constructed objects to other threads, and should be used with caution.
The classic example is a class with a static list of its instances. If the constructor stores this in the list, another
thread could access the object before it’s fully-formed. Even when the storage of this is the last instruction in the constructor,
there’s still a danger if the class is not final. In that case, the initialization of subclasses won’t be complete before
this is exposed.
This rule raises an issue when this is assigned to any globally-visible object in a constructor, and when it is passed to the method
of another object in a constructor
Noncompliant code example
public class Monument {
public static final List<Monument> ALL_MONUMENTS = new ArrayList()<>;
// ...
public Monument(String location, ...) {
ALL_MONUMENTS.add(this); // Noncompliant; passed to a method of another object
this.location = location;
// ...
}
}
Exceptions
This rule ignores instances of assigning this directly to a static field of the same class because that case is covered
by S3010 .
