Android How can I Convert a String to a Editable

Use Editable.Factory.getInstance().newEditable(str) From the android documentation:

Returns a new SpannedStringBuilder from the specified CharSequence. You can override this to provide a different kind of Spanned.

As you probably found out, Editable is an interface so you cannot call new Editable().
However an Editable is nothing more than a String with Spannables, so use SpannableStringBuilder:

Editable editable = new SpannableStringBuilder("Pass a string here");

If you only want to change the Spannables, never the text itself, you can use a basic SpannableString.