http get request from Button onclick function.

Question

I am trying to run http get request on my onclick function from button, I have edittext where in need to supply by user the edittext contain the url to be use on http get request.

my button is :

<Button
        android:id="@+id/mybutton"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="button" 
        android:onClick="Functionbtn"/>

and in my activity I got

public void Functionbtn(View view) {
    Toast.makeText(getApplicationContext(), "this is my toast",
            Toast.LENGTH_LONG).show();

    // Creating JSON Parser instance
    JSONParser jParser = new JSONParser();

    // getting JSON string from URL
    JSONObject json = jParser.getJSONFromUrl(url);

    try {
        // Getting Array of Contacts
        contacts = json.getJSONArray(TAG_CONTACTS);

        // looping through All Contacts
        for (int i = 0; i < contacts.length(); i++) {
            JSONObject c = contacts.getJSONObject(i);

            // Storing each json item in variable
            String id = c.getString(TAG_ID);
            String name = c.getString(TAG_NAME);

            Toast.makeText(getApplicationContext(), id + " = " + name,
                    Toast.LENGTH_LONG).show();

        }
    } catch (JSONException e) {
        e.printStackTrace();
    }

}

and I got an error like :

08-12 18:01:21.353: E/AndroidRuntime(10940): Caused by: android.os.NetworkOnMainThreadException
08-12 18:01:21.353: E/AndroidRuntime(10940):    at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1133)
08-12 18:01:21.353: E/AndroidRuntime(10940):    at java.net.InetAddress.lookupHostByName(InetAddress.java:385)

Some say put my target sdk to 9 but I don't think that is the best practice for this.

Could anyone help me not really sure what to do. Thanks in advance.

Do not do network operation in UI thread. Use async task to achieve your task. — Tarun, Aug 12 '13 at 10:12
Use of [AsyncTask](http://developer.android.com/reference/android/os/AsyncTask.html) is best practice.. — user370305, Aug 12 '13 at 10:12
use async task, follow below link http://stackoverflow.com/questions/17938420/how-to-use-httpget-in-my-app/17938774#17938774 — Gangadhar Nimballi, Aug 12 '13 at 10:18

Kaidul · Accepted Answer · 2013-08-12T10:32:01.383

2

Don't do such network related work inside UI thread. Always do network based work inside AsyncTask anc call it from UI thread.

public void Functionbtn(View view) {
   new GetTaskDone().execute();
}

And:

protected class GetTaskDone extends AsyncTask<Void, Void, String> {

     @Override
     protected void onPreExecute() {
          super.onPreExecute();
          Toast.makeText(getApplicationContext(), "this is my toast",
          Toast.LENGTH_LONG).show();
     }

    protected String doInBackground(Void... params) {

    // Creating JSON Parser instance
    JSONParser jParser = new JSONParser();

    // getting JSON string from URL
    JSONObject json = jParser.getJSONFromUrl(url);

    try {
        // Getting Array of Contacts
        contacts = json.getJSONArray(TAG_CONTACTS);

        // looping through All Contacts
        for (int i = 0; i < contacts.length(); i++) {
            JSONObject c = contacts.getJSONObject(i);

            // Storing each json item in variable
            String id = c.getString(TAG_ID);
            String name = c.getString(TAG_NAME);
            return id + " = " + name;
        }
    } catch (JSONException e) {
        e.printStackTrace();
        return null;
    }
    }

    @Override
    protected void onPostExecute(String result) {
          super.onPostExecute(result);
          Toast.makeText(getApplicationContext(), result,
                    Toast.LENGTH_LONG).show();
    }

}

edited Aug 12 '13 at 10:32

answered Aug 12 '13 at 10:16

Kaidul

15,409
15
81
150

I think you can't call `Toasts` from the background thread. You should do it in the UI Thread. Try implementing `onPreExecute` and `onPostExecute`. – Miro Markaravanes Aug 12 '13 at 10:18
yes, Sir! I didn't notice it. I am fixing it! – Kaidul Aug 12 '13 at 10:19
maybe log can do. thanks for this, got better perspective now. – CaffeineShots Aug 12 '13 at 10:26
1

yes, `Log` can do it. Though I also show as `Toast` :) The summary is you have to do `network` oriented work inside `AsyncTask` – Kaidul Aug 12 '13 at 10:30
it works! thanks. got some modifications to do. thanks thanks big help! – CaffeineShots Aug 12 '13 at 10:38
I think return must be on after catch. – CaffeineShots Aug 12 '13 at 10:51
you can do. I did both inside `try` and `catch` to avoid problems – Kaidul Aug 12 '13 at 10:56

score 1 · Answer 2 · answered Aug 12 '13 at 10:16

Because of android's strict rules, you can't and you shouldn't run network tasks (or similar tasks that take time to complete) on the UI Thread.

Instead you should achieve it by running the tasks in a background thread using AsyncTask or Simple Java Threads.

score 1 · Answer 3 · answered Aug 12 '13 at 11:16

1

Allways remember to run network calls either in a thread or in a asynctask class. preferably asynctask.

answered Aug 12 '13 at 11:16

Udit Kapahi

2,277
1
27
25

If you get any problem regarding geting result from asynctask notify me here. I have a cool techniq . :D – Udit Kapahi Aug 15 '13 at 07:12

http get request from Button onclick function.

3 Answers3