"Invalid IP address" error caught in android-JSON- MySQL

Question

I am trying to make an app that connects to a MySQL database and queries for data. I don't want to insert any data, just search for a keyword in the given entries. I found a couple of tutorials on Google, and this one worked for me.

The layout looks fine, and the app launched well (I tested the app on my actual Nexus 5). But every time I click the button, whether or not there is data in the text box, it just shows "Invalid IP address" in a toast, which I assume is the error caught. My PHP looks like this :

$host='*****';
$uname='*****';
$pwd='*****';
$db="*****";
$con = mysql_connect($host,$uname,$pwd) or die("connection failed");
mysql_select_db($db,$con) or die("db selection failed");
$id=$_REQUEST['id'];
$r=mysql_query("select * from ***** where id='$id'",$con);
while($row=mysql_fetch_array($r))
{
$flag[name]=$row[name];
}
print(json_encode($flag));
mysql_close($con);

Why am I getting this error? And how do I get this to work? Any additional data needed can be provided.

EDIT

Android code

public class MainActivity extends Activity {  
    String id;  
    String name;  
    InputStream is=null;  
    String result=null;  
    String line=null;  
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
        final EditText e_id=(EditText) findViewById(R.id.editText1);  
        Button select=(Button)findViewById(R.id.button1);  
        select.setOnClickListener(new View.OnClickListener() {  
    @Override  
        public void onClick(View v) {  
            // TODO Auto-generated method stub  
            id=e_id.getText().toString();  
            select();  
        }  
    });  
    }  
    public void select()  
    {  
        ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();  
    nameValuePairs.add(new BasicNameValuePair("id",id));  
        try  
        {  
        HttpClient httpclient = new DefaultHttpClient();  
            HttpPost httppost = new   HttpPost("http://kanurajb.co.nf/php/search.php");  
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));  
            HttpResponse response = httpclient.execute(httppost);   
            HttpEntity entity = response.getEntity();  
            is = entity.getContent();  
            Log.e("pass 1", "connection success ");  
    }  
        catch(Exception e) 
    {  
            Log.e("Fail 1", e.toString());  
            Toast.makeText(getApplicationContext(), "Invalid IP Address",  
            Toast.LENGTH_LONG).show();  
    }  
        try
        {  
            BufferedReader reader = new BufferedReader  
                (new InputStreamReader(is,"iso-8859-1"),8);  
                StringBuilder sb = new StringBuilder();  
                while ((line = reader.readLine()) != null)  
        {  
                sb.append(line + "\n");  
            }  
                is.close();  
result = sb.toString();  
            Log.e("pass 2", "connection success ");   
    }  
        catch(Exception e)  
        {  
        Log.e("Fail 2", e.toString());   
    }  
    try  
        {  
            JSONObject json_data = new JSONObject(result);  
            name=(json_data.getString("name"));  
        Toast.makeText(getBaseContext(), "Name : "+name,  
            Toast.LENGTH_SHORT).show();  
        }    
        catch(Exception e)   
        {  
            Log.e("Fail 3", e.toString());    
        }   
    }  
    @Override  
    public boolean onCreateOptionsMenu(Menu menu) {  
        getMenuInflater().inflate(R.menu.main, menu);  
        return true;  
    }  
}

Answer 1

See the answer here..It correctly tells you how to deal with the exception. It says..

This exception is thrown when an application attempts to perform a networking operation on its main thread. Run your code in AsyncTask:

Chenge your code as follows..I have changed your select() as follows..This is just for you to get a better understanding about AsyncTask.

class RetrieveFeedTask extends AsyncTask<Void, Void, Boolean> {

  private Exception exception;

  protected Boolean doInBackground(String... urls) {
      try {
        Boolean failedflag=false;
        ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();  
        nameValuePairs.add(new BasicNameValuePair("id",id));  
        try  
        {  
            HttpClient httpclient = new DefaultHttpClient();  
            HttpPost httppost = new   HttpPost("http://kanurajb.co.nf/php/search.php");  
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));  
            HttpResponse response = httpclient.execute(httppost);   
            HttpEntity entity = response.getEntity();  
            is = entity.getContent();  
            Log.e("pass 1", "connection success ");  
        }  
        catch(Exception e) 
        {  
            failedflag=true;
            Log.e("Fail 1", e.toString());           
        }  
        try
        {  
            BufferedReader reader = new BufferedReader  
                (new InputStreamReader(is,"iso-8859-1"),8);  
                StringBuilder sb = new StringBuilder();  
                while ((line = reader.readLine()) != null)  
                {  
                    sb.append(line + "\n");  
                }  
                is.close();  
                result = sb.toString();  
                Log.e("pass 2", "connection success ");   
        }  
        catch(Exception e)  
        {  
            failedflag=true;
            Log.e("Fail 2", e.toString());   
        }  
        try  
        {  
            JSONObject json_data = new JSONObject(result);  
            name=(json_data.getString("name"));   
        }    
        catch(Exception e)   
        {  
            failedflag=true;
            Log.e("Fail 3", e.toString());    
        }   
        return failedflag;
  }

  protected void onPostExecute(Boolean flag) { 
      // TODO: do something with the flag
      if(!flag){
          Toast.makeText(getApplicationContext(), "Failed",  
        Toast.LENGTH_LONG).show();
      }
  }
}

How to execute the task: In MainActivity.java file you can add this line within your oncreate() method

new RetrieveFeedTask().execute();

Don't forget to add this to AndroidManifest.xml file:

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