import org.jetbrains.annotations.Nullable; class Test { String foo(int i, boolean flag) { String xxx = newMethod(i, flag); if (xxx == null) return null; System.out.println(xxx); return null; } @Nullable private String newMethod(int i, boolean flag) { String xxx = ""; if (flag) { for (int j = 0; j < 100; j++) { if (i == j) { return null; } } } return xxx; } }