Clickable URLs in Android TextViews

http://blog.elsdoerfer.name/2009/10/29/clickable-urls-in-android-textviews/

Android’s TextView widget can contain clickable URLs. It can easily make web addresses open in the browser, or connect phone numbers with the dialer. All that is amazing compared to the last GUI framework I used, Delphi’s once greatVCL).

Unfortunately, both TextView and the Linkify utility it uses basically hardcode URL click handling to Intents, by way of theURLSpans they create. What if we want the link to affect something within your own Activity, say, display a dialog, or enable a filter?

For example, in Autostarts, if the user’s filters cause the application list to be empty, I wanted to display an explanatory message, and provide a quick and easy way for the user to rectify the situation, i.e. lead him towards the filter selection dialog. Making the whole text clickable is hard to get right visually, and I didn’t like the idea of a button too much. A link within the text seemed perfect.

Now, we could just use a custom URL scheme of course, and register our Activity to handle Intents for that scheme, but that seemed much too heavy, if not hacky. Why shouldn’t we be able to just hook up an onClick handler?

As mentioned, URLSpan doesn’t allow us to change the way it handles clicks (it always sends off an Intent), but we can create a subclass:

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1. static class InternalURLSpan extends ClickableSpan {  
2.     OnClickListener mListener;  
3.   
4.     public InternalURLSpan(OnClickListener listener) {  
5.         mListener = listener;  
6.     }  
7.   
8.     @Override  
9.     public void onClick(View widget) {  
10.         mListener.onClick(widget);  
11.     }  
12. }  

That looks pretty decent. Actually using that class it is tougher. There is no way to tellTextView or Linkify to use our custom span. In fact, Linkify actually hasa method (applyLink) that would be nearly perfect to override, but declares it final.

So, we end up having to generate the spans manually; note nice, but hey, it works.

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1. SpannableString f = new SpannableString("....")  
2. f.setSpan(new InternalURLSpan(new OnClickListener() {  
3.         public void onClick(View v) {  
4.             showDialog(DIALOG_VIEW_OPTIONS);  
5.         }  
6.     }), x, y, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);  

We probably also want the user to jump to your link my moving the focus (e.g. using the trackball), which we can do by setting the proper movement method:

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1. MovementMethod m = emptyText.getMovementMethod();  
2. if ((m == null) || !(m instanceof LinkMovementMethod)) {  
3.     if (textView.getLinksClickable()) {  
4.         textView.setMovementMethod(LinkMovementMethod.getInstance());  
5.     }  
6. }  

This entry was posted by admin on 05:28, Oct 29th 2009 and filed inAndroid.

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Why did you have to create a custom subclass of ClickableSpan. Instead you can create a ClickableSpan variable:

ClickableSpan clickable = new ClickableSpan() {@Overridepublic void onClick(View widget) {            Log.e("select text", "hi");}};SpannableString f = new SpannableString("....") ;f.setSpan(clickable,  x, y, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);