select from a small amount of options in spring shell

Question

I am currently trying to make an cli app with Spring Shell.

I want the user to able to fast pick one of 2-3 options. My current code works fine in eclipse but when I sta

Answer 1

I use TextIO for this to do something similar. More specifically, I use the read method on [IntInputReader][2] which is handy as according to its docs:

Reads a value of type T. It repeatedly prompts the users to enter the value, until they provide a valid input string.

As I've needed this functionality many times in my Spring Shell application (for users to select from different types of objects), I wrote a generic method which

Presents the user with a list of items of a given type {@code T} and prompts them to select one or more. Optionally, once selection is complete, the user is presented with a summary of their selection for their confirmation.

Unfortunately StackOverflow is playing havoc with my Javadoc, so I've created a Gist with the full documented method.

  public  List cliObjectSelector(List items, boolean allowMultiple, 
  boolean requireConfirmation, @Nullable String customPromptMessage,
  Function f) throws OperationCancelledException {

if(items == null || items.isEmpty()) {
  textIO.getTextTerminal().print("No items found.  Cannot continue");
  throw new OperationCancelledException("The provided list of items is empty");
}

String userPrompt = (customPromptMessage != null) ? customPromptMessage + ":\n" : 
  String.format("Please select one of the %d items from the list:\n", items.size());

List optionsList = items.stream()
    .map(item -> {
      return String.format("[%d] - %s", items.indexOf(item), f.apply(item));
    }).collect(Collectors.toList());

List selectedItems = new ArrayList<>();

optionsList.add(0, userPrompt);

while(true) {
  textIO.getTextTerminal().println(optionsList);

  T selected = items.get(
      textIO.newIntInputReader()
      .withMinVal(0)
      .withMaxVal(items.size() - 1)
      .read("Option number"));

  selectedItems.add(selected);

  if(allowMultiple == false) {
    break;
  }

  if( ! askYesNo("Select another item?")) {
    break;
  }
}

if(requireConfirmation == false) {
  return selectedItems;
}

if(confirmSelection(selectedItems.stream()
    .map(item -> f.apply(item))
    .collect(Collectors.toList()))) {
  return selectedItems;
} else {
  throw new OperationCancelledException();
}
}

Sample usage:

  @ShellMethod(
  key = "select-something",
  value = "Select something")
public void select() {
    Instance selected = cliObjectSelector(instances, false, requireConfirmation,
        "Please select one of the " + instances.size() + " instances from the list",
        instance -> instance.getX().getName()).get(0);
  }