Unsafe lazy initialization of 'static' field

Reports static variables that are lazily initialized in a non-thread-safe manner.

Lazy initialization of static variables should be done with an appropriate synchronization construct to prevent different threads from performing conflicting initialization.

When applicable, a quick-fix, which introduces the lazy initialization holder class idiom, is suggested. This idiom makes use of the fact that the JVM guarantees that a class will not be initialized until it is used.

Example:

class X {
  private static List<String> list;

  public List<String> getList() {
    if (list == null) {
      list = List.of("one", "two", "tree");
    }
    return list;
  }
}

After the quick-fix is applied:

class X {
  private static final class ListHolder {
    static final List<String> list = List.of("one", "two", "tree");
  }

  public List<String> getList() {
    return ListHolder.list;
  }
}

Inspection Details
Available in:	IntelliJ IDEA 2023.3, Qodana for JVM 2023.3
Plugin:	Java, 233.SNAPSHOT

Last modified: 13 July 2023