Autocomplete

Additional

Language
Java
Version
v1.1.0 (Apr 19, 2018)
Created
Apr 21, 2017
Updated
Apr 19, 2018
Owner
Mattia Iavarone (natario1)
Contributor
Mattia Iavarone (natario1)
1
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Autocomplete

Simple yet powerful autocomplete behavior for EditTexts, to avoid working with MultiAutoCompleteTextView APIs.

implementation 'com.otaliastudios:autocomplete:1.1.0'

To see it in action, take a look at the sample app in the sample module.

Usage

Autocomplete let's you add autocomplete behavior to any EditText of your choice. The workflow is as follows:

  • User types stuff into the edit text
  • AutocompletePolicy detects if typed text should trigger the autocomplete popup
  • If yes, the popup is shown
  • AutocompletePolicy extracts the query string from text. For instance, if text is Look at this @john, you might want to look for john users in your database
  • The query string is passed to AutocompletePresenter, that shows a list of items for that query
  • When some item is clicked, AutocompleteCallback is notified and tells whether the popup should be dismissed or not.

These are the base components of the library. You will build an Autocomplete instance passing each component you need, and that's it.

Autocomplete.on(editText)
  .with(autocompletePolicy)
  .with(autocompleteCallback)
  .with(autocompletePresenter)
  .with(popupBackground)
  .with(popupElevation)
  .build();

AutocompletePolicy

This is an interface that controls when to show/hide the popup. For simple cases (single autocompletion, with just one result, similar to AutocompleteTextView) you can leave this unspecified. The library will fallback to Autocomplete.SimplePolicy:

public class SimplePolicy implements AutocompletePolicy {
    @Override
    public boolean shouldShowPopup(Spannable text, int cursorPos) {
        return text.length() > 0;
    }

    @Override
    public boolean shouldDismissPopup(Spannable text, int cursorPos) {
        return text.length() == 0;
    }

    @Override
    public CharSequence getQuery(Spannable text) {
        return text;
    }

    @Override
    public void onDismiss(Spannable text) {}
}

For more complex situations, you can go implementing the methods:

  • shouldShowPopup(Spannable, int): called to understand whether the popup should be shown. For instance, you might want to trigger the popup only when the hashtag character '#' is typed.
  • shouldDismissPopup(Spannable, int): whether the popup should be hidden. The typical implementation would simply be to return !shouldShowPopup(), but that is up to you.
  • getQuery(Spannable): called to understand which part of the text should be passed to presenters. For instance, user might have typed @john but you want to query for john of course.
  • onDismiss(Spannable): this is the moment you should clear any span you have added to the text.

For the typical case of #hashtags, @usernames or whatever is triggered by a certain character, the library provides the CharPolicy class. It works as multi-autocomplete as well (e.g. for texts like you should see this @john @pete).

Autocomplete.on(editText)
  .with(new CharPolicy('#'))
  .with(autocompletePresenter)
  .build();

AutocompletePresenter

The presenter controls the display of items and their filtering when a query is selected. It is recommended to extend RecyclerViewPresenter, which shows a RecyclerView list. For more complex needs, look at the base AutocompletePresenter class and its comments.

Note: starting from 1.1.0, if the view returned by AutocompletePresenter has 0 height, this is read as a no-data signal and the popup will be dismissed. Not doing so would cause drawing artifacts, by leaving the popup in a weird state.

If you are performing asynchronous loading, make sure to give some height to your view, for example by returning a 'loading' item from your adapter, or adding vertical padding.

RecyclerViewPresenter

This automatically inflates a RecyclerView into the popup. Some relevant callbacks to be overriden:

  • instantiateAdapter(): you should provide an adapter for the recycler here.
  • instantiateLayoutManager(): same for the layout manager. Defaults to vertical LinearLayoutManager. Complex managers might lead to UI inconsistencies.
  • getPopupDimensions(): return dimensions for the popup (width, height, maxWidth, maxHeight).
  • onViewShown(): you can perform further initialization on the recycler. The list now is about to be requested.
  • onQuery(CharSequence): we have a query from the edit text, as returned by AutocompletePolicy. This is the time to display a list of results corresponding to this filter.
  • onViewHidden(): release resources here if needed.

When a list item is clicked, please ensure you are calling dispatchClick(item) to dispatch the click event to the AutocompleteCallback, if present.

AutocompleteCallback

public interface AutocompleteCallback<T> {
    boolean onPopupItemClicked(Editable editable, T item);
    void onPopupVisibilityChanged(boolean shown);
}

AutocompleteCallback controls what happens when either the popup visibility changes, or when an item is selected. Typically at this point you might want to insert a String related to that item into the EditText.

This should be done by acting on the Editable interface that you should already know, using methods like editable.insert() or editable.replace().

Contributing

You are welcome to contribute with issues, PRs or suggestions.