How to subscript a text on a spinner in Android?

Question

I am using a spinner with some text (String) and I would like to write the chemical expression MgCl2 with the number 2 subscripted. How can I do it?

I have seen some posts telling about to use Html.fromHtml() but AndroidStudio says this method is deprecated. You can see my code below.

Spinner spinner1 = (Spinner) findViewById(R.id.spinner1);

List<String> list = new ArrayList<String>();
list.add("MgCl2");

ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_item, list);

dataAdapter.setDropDownViewResource(android.R.layout.simple_expandable_list_item_1);
spinner1.setAdapter(dataAdapter);

Answer 1

You can do this directly with a SpannableString.

SpannableString s = new SpannableString("MgCl2");
s.setSpan(new SubscriptSpan(), 5, 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

Your ArrayAdapter can be typed as <CharSequence>. Any downstream setText calls can take a CharSequence argument (instead of the String you're using now).

Note that SpannableString is immutable. For more complex constructions, you may want SpannableStringBuilder.

Probably, you should be aware of the set of CharacterStyle subclasses. They represent all the effects you can apply to a Spanned of any concrete type.

Answer 2

You can use SpannableStringBuilder to create text with a subscript. Something along the lines of:

SpannableStringBuilder span = new SpannableStringBuilder("MgCl2");
span.setSpan(new SubscriptSpan(), 4, 5, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

This will make the 2 a subscript, however it will retain it's size. To make it smaller add a RelativeSizeSpan as well like this:

span.setSpan(new RelativeSizeSpan(0.75f), 3, 4, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

You'll have to change your ArrayList type though, to either CharSequence or StringBuilder