Linkify() - activating links

Question

I have added links to text that is surrounded by [square brackets] in a popup dialog box. The links however, are not clickable (nothing happens when they are pressed). I can't work out why(!)

Here is my dialog box activity:

public void popupDefinition(CharSequence term, LinkedHashMap<String, String> dictionaryMap){
    SpannableString definition = new SpannableString(dictionaryMap.get(term)); // grab the definition by checking against the dictionary map hash
    Linkify.addLinks(definition, pattern, scheme); // find text in square brackets, add links

    AlertDialog alertDialog = new AlertDialog.Builder(ListProjectActivity.this).create(); // create a dialog box
    alertDialog.setMessage(definitionFormatted); // set dialog box message
    alertDialog.show(); // actually display the dialog box
    }

'scheme' and 'pattern' are defined earlier, as follows:

final static Pattern pattern = Pattern.compile("\\[[^]]*]"); // defines the fact that links are bound by [square brackets]
final String scheme = "http://example.com/"; // THIS IS NOT WORKING

Why, when I tap the links that appear (they appear nicely underlined in blue), do they not cause any response?

I'm not actually trying to launch URL links (I'll be redirecting the ACTION_VIEW intent when it does occur), but I need to confirm that some sort of response is happening before I get to that...

Answer 1

I'm not actually trying to launch URL links

Since you don't need to use URLs, don't bother with trying to create a custom Linkify scheme since it only creates URLSpans. You simply want to start an Activity from a keyword in a TextView. As I stated in one of your similar, but not duplicate, questions I would use a custom span, introducing ActivitySpan:

public class ActivitySpan extends ClickableSpan {
    String keyword;
    public ActivitySpan(String keyword) {
        super();
        this.keyword = keyword;
    }

    @Override
    public void onClick(View v) {
        Context context = v.getContext();
        Intent intent = new Intent(context, AnotherActivity.class);
        intent.putExtra("keyword", keyword);
        context.startActivity(intent);
    }
}

There are no bells or whistles here, this span takes a [keyword] that you surrounded in brackets and passes it to the another Activity.

While I don't like the idea of using Linkify because of URLSpans, its pattern matching and span creation is great, so I copied and modified it:

private void addLinks(TextView textView, Pattern pattern) {
    SpannableString spannable = SpannableString.valueOf(textView.getText());
    Matcher matcher = pattern.matcher(spannable);

    // Create ActivitySpans for each match
    while (matcher.find())
        spannable.setSpan(new ActivitySpan(matcher.group()), matcher.start(), matcher.end(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

    // Set new spans in TextView
    textView.setText(spannable);

    // Listen for spannable clicks, if not already
    MovementMethod m = textView.getMovementMethod();
    if ((m == null) || !(m instanceof LinkMovementMethod)) {
        if (textView.getLinksClickable()) {
            textView.setMovementMethod(LinkMovementMethod.getInstance());
        }
    }
}

As a note, this method doesn't remove the [brackets] surrounding each keyword, but you can easily do this in the while-loop.

To use this, simply pass a TextView and Pattern to addLinks() in onCreate() and Voila!

---

A working example for you:

public class Example extends Activity {
    Pattern pattern = Pattern.compile("\\[[^]]*]");

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        popupDefinition("Example: A [pattern] or [model], as of something to be [imitated] or [avoided]");
    }

    // It seems like you can call "popupDefinition(dictionaryMap.get(term));" rather than pass both.  
    public void popupDefinition(String string){
        SpannableString spannable = new SpannableString(string);
        Matcher matcher = pattern.matcher(spannable);

        // Create ActivitySpans for each match
        while (matcher.find())
            spannable.setSpan(new ActivitySpan(matcher.group()), matcher.start(), matcher.end(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

        // Create a new TextView with these spans and enable the clickable links
        TextView textView = new TextView(this);
        textView.setText(spannable);
        textView.setMovementMethod(LinkMovementMethod.getInstance());

        // Create and display an AlertDialog with this TextView
        AlertDialog alertDialog = new AlertDialog.Builder(this)
                .setView(textView)
                .create(); 
        alertDialog.show(); 
    }


    public class ActivitySpan extends ClickableSpan {
        String keyword;
        public ActivitySpan(String keyword) {
            super();
            this.keyword = keyword;
        }

        @Override
        public void onClick(View v) {
            Context context = v.getContext();
            Toast.makeText(context, keyword, Toast.LENGTH_SHORT).show();
        }
    }
}