Even if the PHP file in the browser chrome is normal, the JSON object is empty when Android is logged in.

Follow my course

public class fetchUserDataAsyncTask extends AsyncTask {
 User user;
 GetUserCallback userCallBack;

 public fetchUserDataAsyncTask(User user, GetUserCallback userCallBack) {
 this.user = user;
 this.userCallBack = userCallBack;
 }

 @Override
 protected User doInBackground(Void ... params) {
 ArrayList dataToSend = new ArrayList<>();
 dataToSend.add(new BasicNameValuePair("username", user.username));
 dataToSend. add(new BasicNameValuePair("password", user.password));

 HttpParams httpRequestParams = new BasicHttpParams();
 HttpConnectionParams.setConnectionTimeout(httpRequestParams,
 CONNECTION_TIMEOUT);
 HttpConnectionParams.setSoTimeout(httpRequestParams,
 CONNECTION_TIMEOUT);

 HttpClient client = new DefaultHttpClient(httpRequestParams);
 HttpPost post = new HttpPost(SERVER_ADDRESS
 + "FetchUserData.php");

 User returnedUser = null;

 try {
 post.setEntity(new UrlEncodedFormEntity(dataToSend));
 HttpResponse httpResponse = client.execute(post);
< br /> HttpEntity entity = httpResponse.getEntity();
 String result = EntityUtils.toString(entity);
 JSONObject jObject = new JSONObject(result);

 if (jObject .length() != 0){
 Log.v("happened", "2");
 String name = jObject.getString("name");
 int age = jObject .getInt("age");

 returnedUser = new User(name, age, user.username, user.password);
 }



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

 return returnedUser;
 }

 @Override
 protected void onPostExecute(User returnedUser) {< br /> super.onPostExecute(returnedUser);
 progressDialog.dismiss();
 userCallBack.done(returnedUser);
 }
}

Get Php File Fetch_User_Data.php

$con=mysqli_connect("localhost","root","","loginregister"); 

if (mysqli_connect_errno($con))
{
 echo "Failed to connect to MySQL: ", mysqli_connect_error();
}

if (isset($_POST["password"])) {$password = $_POST

["password"];}else $password ='bimbomix';
if ( isset($_POST["username"])) {$username = $_POST

["username"];}else $username ='bimbomix';



$statement = mysqli_prepare($con, "SELECT * FROM user WHERE 

username =? AND password = ?");
mysqli_stmt_bind_param($statement, "ss" , $username, 

$password);
mysqli_stmt_execute($statement);
mysqli_stmt_store_result($statement);
mysqli_stmt_bind_result($statement, $user_id, $name, $age, 

$username, $password);

$user = array();

while(mysqli_stmt_fetch($statement)){
 $user ['name'] = $name; 
 $user['age'] = $age;
 $user['username'] = $username;
 $user['password'] = $password; 
}

echo json_encode($user);


mysqli_close($con);

 ?>

Hard coded test

User returnedUser=null;
 try {

 post.setEntity(new UrlEncodedFormEntity(dataToSend));

 HttpResponse httpResponse = client.execute(post);

 HttpEntity entity = httpResponse.getEntity();

 String result = EntityUtils.toString(entity);
//until here hardcoding fills correctly returnedUser
 JSONObject jObject = new JSONObject(result) ;
returnedUser = new User("hello", 42, user.username, user.password);
// this is hardcoded string that let returnedUser ==null
// so perhaps problem is in jObject 

if (jObject.length() != 0){
 Log.v("happened", "2");
 String name = jObject.getString ("name");
 int age = jObject.getInt("age");

 // returnedUser = new User(name, age, user.username, user.password); 
 }



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

 return returnedUser;
 }

I’m sorry. The problem is simple, even if it drives me crazy for a week! Check the fetch file “Fetch_User_Data.php”, then check the string, I will call it “FetchUserData.php”, you will be done…