Question

I have written some code to do a httpGet and then return the JSON back to the main thread. Sometimes though the server is down and I want to report back to the main thread that the server is down but don’t know how to do it properly using the handler.

My code looks like this:

public class httpGet implements Runnable {

    private final Handler replyTo;
    private final String url;

    public httpGet(Handler replyTo, String url, String path, String params) {
        this.replyTo = replyTo;
        this.url = url;
    }

    @Override
    public void run() {
         try {
             // do http stuff //
         } catch (ClientProtocolException e) {
            Log.e("Uh oh", e);
            //how can I report back with the handler about the 
            //error so I can update the UI 
         }
    }
}

Answer 1

Send a message to the handler, with some error code, for example:

Message msg = new Message();
Bundle data = new Bundle();
data.putString("Error", e.toString());
msg.setData(data);
replyTo.sendMessage(msg);

In the handler’s handleMessage implementation handle this message.

The handler should look like this:

Handler handler = new Handler() {
     @Override
     public void handleMessage(Message msg) {
         Bundle data = msg.getData();
         if (data != null) {
              String error = data.getString("Error");
              if (error != null) {
                  // do what you want with it
              }
         }
     }
};