Question

I’m following the excellent tutorial on Android login and register at http://www.androidhive.info/2012/01/android-login-and-registration-with-php-mysql-and-sqlite/

I’ve implemented the code into my own project but i kept on getting errors. So I decided to try if his code was working and it did just fine. After many hours of searching what was wrong i just decided to copy his code and go from there. But even after just copy-pasting his code into my project I still keep on getting errors.

Here’s my logcat error, if anyone could point me in the right direction I would be very glad.

01-15 10:12:26.822: E/AndroidRuntime(1935): FATAL EXCEPTION: main
01-15 10:12:26.822: E/AndroidRuntime(1935): android.os.NetworkOnMainThreadException
01-15 10:12:26.822: E/AndroidRuntime(1935): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)                                        
01-15 10:12:26.822: E/AndroidRuntime(1935):     at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at libcore.io.IoBridge.connect(IoBridge.java:112)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at java.net.Socket.connect(Socket.java:842)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at com.example.androidbasic12.library.JSONParser.getJSONFromUrl(JSONParser.java:42)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at com.example.androidbasic12.library.UserFunctions.loginUser(UserFunctions.java:38)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at com.example.androidbasic12.MainActivity$1.onClick(MainActivity.java:57)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at android.view.View.performClick(View.java:4202)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at android.view.View$PerformClick.run(View.java:17340)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at android.os.Handler.handleCallback(Handler.java:725)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at android.os.Handler.dispatchMessage(Handler.java:92)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at android.os.Looper.loop(Looper.java:137)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at android.app.ActivityThread.main(ActivityThread.java:5039)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at java.lang.reflect.Method.invokeNative(Native Method)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at java.lang.reflect.Method.invoke(Method.java:511)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
01-15 10:12:26.822: E/AndroidRuntime(1935):     at dalvik.system.NativeStart.main(Native Method)`

JSONParser.class:

public class JSONParser {

static InputStream is = null;
static JSONObject jObj = null;
static String json = "";

// constructor
public JSONParser() {

}

public JSONObject getJSONFromUrl(String url, List<NameValuePair> params) {

    // Making HTTP request
    try {
        // defaultHttpClient
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);
        httpPost.setEntity(new UrlEncodedFormEntity(params));

        HttpResponse httpResponse = httpClient.execute(httpPost);
        HttpEntity httpEntity = httpResponse.getEntity();
        is = httpEntity.getContent();

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    try {
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                is, "iso-8859-1"), 8);
        StringBuilder sb = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
        }
        is.close();
        json = sb.toString();
        Log.e("JSON", json);
    } catch (Exception e) {
        Log.e("Buffer Error", "Error converting result " + e.toString());
    }

    // try parse the string to a JSON object
    try {
        jObj = new JSONObject(json);            
    } catch (JSONException e) {
        Log.e("JSON Parser", "Error parsing data " + e.toString());
    }

    // return JSON String
    return jObj;

}

}

Answer 1

You’re performing a network operation in your main UI thread. If your target SDK is 11 (Honeycomb) or higher this will throw a NetworkOnMainThreadException because this behaviour can block the UI and lead to an unresponsive app.

You have to use an AsyncTask to get avoid this, by loading the data in its doInBackground(..) method.