IssueTracker

javac will add synthetic accessor methods when calling private methods on inner classes and it will also add synthetic constructors when calling private constructors (and it adds an empty class to disambiguate the overload). While small, these synthetic methods (and classes) can add up towards the dex method count–especially for libraries which should be striving to have the smallest impact possible.

A lint check could detect these situations and recommend that the private method/ctor had its visibility increased to package-scope to avoid the need for the synthetics.

Specifically, for this test code:

    public class Test {
      public static void main(String... args) {
        TestInner inner = new TestInner();
        inner.run();
        inner.bye();
      }

      private static final class TestInner implements Runnable {
        private TestInner() {}
        @Override public void run() {
          System.out.println("Hello, world!");
        }
        private void bye() {
          System.out.println("Goodbye, world!");
        }
      }
    }

The `new TestInner()` should be flagged and `inner.bye()` should be flagged.

If you wanted, you could instead flag the private constructor and private method directly and then list the call sites which are accessing them from outside the private scope, but I think that would be harder to do.