Cannot connect to PHP using android application

Question

Now I was developing an application which requires connection to a database, I tried to connect the android application directly to MYSQL but I failed and alot of people said that I should do it through PHP. So in the mean time I am trying this code to connect to a PHP.

package com.climacon.androidapp;



import java.io.BufferedReader;
import java.io.InputStream;

import java.io.InputStreamReader;


import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;

import android.util.Log;

public class Phpmysql {
  public static JSONObject connections (String url) {
    InputStream is = null;
    String result = "";
    JSONObject jArray = null;

    // Download JSON data from URL
    try {
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("http://192.168.1.20/Project/");
        HttpResponse response = httpclient.execute(httppost);
        HttpEntity entity = response.getEntity();
        is = entity.getContent();

    } catch (Exception e) {
        Log.e("log_tag", "Error in http connection " + e.toString());
    }

    // Convert response to string
    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 + "
");
        }
        is.close();
        result = sb.toString();
    } catch (Exception e) {
        Log.e("log_tag", "Error converting result " + e.toString());
    }

    try {

        jArray = new JSONObject(result);
    } catch (JSONException e) {
        Log.e("log_tag", "Error parsing data " + e.toString());
    }

    return jArray;
  }
}

And I call this function (connections()) from another class but it doesn't work and it gives me the following error message

Error in http connection android.os.NetworkOnMainThreadException
Error converting result java.lang.NullPointerException: lock == null
Error parsing data org.json.JSONException: End of input at character 0 of 

and I added

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

Now it is working using the ASYNC task but when i try

NNode node = null;
node.set_temp(jObject.length());    
value4.setText(String.valueOf(tempprogress))

i get the following error

E/JSON Parser(3336): Error parsing data org.json.JSONException: Value <!DOCTYPE of type     java.lang.String cannot be converted to JSONObject
E/ActivityManager(714): App crashed! Process: com.climacon.androidapp
E/AndroidRuntime(3336): FATAL EXCEPTION: main
E/AndroidRuntime(3336): Process: com.climacon.androidapp, PID: 3336
E/AndroidRuntime(3336): java.lang.NullPointerException
E/AndroidRuntime(3336):     at   com.climacon.androidapp.climatemonitor$ConnectToPHP.onPostExecute(climatemonitor.java:83)
E/AndroidRuntime(3336):     at com.climacon.androidapp.climatemonitor$ConnectToPHP.onPostExecute(climatemonitor.java:1)
E/AndroidRuntime(3336):     at android.os.AsyncTask.finish(AsyncTask.java:632)
E/AndroidRuntime(3336):     at android.os.AsyncTask.access$600(AsyncTask.java:177)
E/AndroidRuntime(3336):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
E/AndroidRuntime(3336):     at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime(3336):     at android.os.Looper.loop(Looper.java:157)
E/AndroidRuntime(3336):     at android.app.ActivityThread.main(ActivityThread.java:5872)
E/AndroidRuntime(3336):     at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(3336):     at java.lang.reflect.Method.invoke(Method.java:515)
E/AndroidRuntime(3336):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1069)
E/AndroidRuntime(3336):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:885)
E/AndroidRuntime(3336):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

Error in http connection android.os.NetworkOnMainThreadException

Above exception state that you are doing network calling on main thread, you have to do it in asynctask or handler. Have a look at below class:

class ConnectToPHP extends AsyncTask<String, String, String>
{
    @Override
    protected void onPreExecute()
    {
        // TODO Auto-generated method stub
        // show progress dialog here
        super.onPreExecute();
    }

    @Override
    protected String doInBackground(String... params)
    {
       // TODO Auto-generated method stub
       JSONObject jObject = Phpmysql.connections(params[0]);
       System.out.println(jObject.toString());
       // do your code here
       return null;
    }

    @Override
    protected void onPostExecute(String result)
    {
        // TODO Auto-generated method stub
        // dismiss progress dialog here
        super.onPostExecute(result);
    }

}

Call this asynctask class in onCreate() of activity like below:

String my_url = "192.168.1.20/Project/index.php";
new ConnectToPHP.execute(my_url);