public Coder getDefaultOutputCoder()

in sdk/src/main/java/com/google/cloud/dataflow/sdk/transforms/Create.java [245:295]
44 lines of code
12 McCabe index (conditional complexity)

    public Coder<T> getDefaultOutputCoder(PInput input) throws CannotProvideCoderException {
      if (coder.isPresent()) {
        return coder.get();
      }
      // First try to deduce a coder using the types of the elements.
      Class<?> elementClazz = Void.class;
      for (T elem : elems) {
        if (elem == null) {
          continue;
        }
        Class<?> clazz = elem.getClass();
        if (elementClazz.equals(Void.class)) {
          elementClazz = clazz;
        } else if (!elementClazz.equals(clazz)) {
          // Elements are not the same type, require a user-specified coder.
          throw new CannotProvideCoderException(
              "Cannot provide coder for Create: The elements are not all of the same class.");
        }
      }

      if (elementClazz.getTypeParameters().length == 0) {
        try {
          @SuppressWarnings("unchecked") // elementClazz is a wildcard type
          Coder<T> coder = (Coder<T>) input.getPipeline().getCoderRegistry()
              .getDefaultCoder(TypeDescriptor.of(elementClazz));
          return coder;
        } catch (CannotProvideCoderException exc) {
          // let the next stage try
        }
      }

      // If that fails, try to deduce a coder using the elements themselves
      Optional<Coder<T>> coder = Optional.absent();
      for (T elem : elems) {
        Coder<T> c = input.getPipeline().getCoderRegistry().getDefaultCoder(elem);
        if (!coder.isPresent()) {
          coder = Optional.of(c);
        } else if (!Objects.equals(c, coder.get())) {
          throw new CannotProvideCoderException(
              "Cannot provide coder for elements of " + Create.class.getSimpleName() + ":"
              + " For their common class, no coder could be provided."
              + " Based on their values, they do not all default to the same Coder.");
        }
      }

      if (!coder.isPresent()) {
        throw new CannotProvideCoderException("Unable to infer a coder. Please register "
            + "a coder for ");
      }
      return coder.get();
    }