DoubleBraceInitialization

Reports Double Brace Initialization.

Compared to regular initialization, double brace initialization provides worse performance since it requires loading an additional class.

It may also cause failure of equals() comparisons if the equals() method doesn't accept subclasses as parameters.

Double brace initialization may cause memory leaks when used in a non-static context. This is because it defines an anonymous class that will reference the surrounding object, when compiled with javac from before Java 18.

In addition, before Java 9, double brace initialization couldn't be combined with the diamond operator since it was incompatible with anonymous classes.

Example:

List<Integer> list = new ArrayList<>() {{
    add(1);
    add(2);
  }};

After the quick-fix is applied:

List<Integer> list = new ArrayList<>();
  list.add(1);
  list.add(2);