Wait until the user stops typing before executing a heavy search in searchview

Question

Search is central in my app and I need it to work well. Right now I have a SearchView. I need to display the results inline, so I'm using this code.

    searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
        @Override
        public boolean onQueryTextSubmit(String query) {
            srl.setVisibility(View.GONE);
            return false;
        }

        @Override
        public boolean onQueryTextChange(String query) {
            currentQuery = query;
            if (query.length()>= 3) {
                searchFor(currentQuery);
            } else {
                srl.setVisibility(View.GONE);
            }
            return false;
        }
    });

The problem may be obvious. Because I use firebase, my searchFor() function is rather heavy and I don't need it to be executed for every single letter. This not only destroys the user experience, it sometimes literally crashes my app if you write down longer words.

What I want is to search when the user stops typing. I guess I need to have a handler that delays it by a second and then cancel that handler everytime a letter key is pressed and set a new one. This theoretically makes sense. I just haven't been able to pull this off myself for a searchView.

Help would be appreciated!

Answer 1

The easiest way to achieve that is RxJava's debounce operator.

With combination of Jake Wharton's RxBinding you'll end up with something like this:

RxSearchView.queryTextChanges(searchView)
        .debounce(1, TimeUnit.SECONDS) // stream will go down after 1 second inactivity of user
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(new Consumer<CharSequence>() {
            @Override
            public void accept(@NonNull CharSequence charSequence) throws Exception {
                // perform necessary operation with `charSequence`
            }
        });

Answer 2

For those who do not want to use RxJava :

final Handler handler = new Handler();
SearchView searchView = (SearchView) findViewById(R.id.search_view);

searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {

        public boolean onQueryTextChange(final String query) {
            handler.removeCallbacksAndMessages(null);
            handler.postDelayed(new Runnable() {
                @Override
                public void run() {
                    // do stuff
                }
            }, 400);
            return false;
        }
});