I'm creating a user login and registration application with Android Studio but I'm a beginner and getting a JSONException.
I used this tutorial to put together my code.
Here's the error information:
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ org.json.JSONException: Value <!DOCTYPE of type java.lang.String cannot be converted to JSONObject
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at org.json.JSON.typeMismatch(JSON.java:111)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at org.json.JSONObject.<init>(JSONObject.java:159)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at org.json.JSONObject.<init>(JSONObject.java:172)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.example.dev5.registration.app.RegisterActivity$3.onResponse(RegisterActivity.java:119)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.example.dev5.registration.app.RegisterActivity$3.onResponse(RegisterActivity.java:110)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:60)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:30)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:99)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at android.os.Handler.handleCallback(Handler.java:733)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at android.os.Handler.dispatchMessage(Handler.java:95)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at android.os.Looper.loop(Looper.java:136)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at android.app.ActivityThread.main(ActivityThread.java:5001)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at java.lang.reflect.Method.invokeNative(Native Method)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at java.lang.reflect.Method.invoke(Method.java:515)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at dalvik.system.NativeStart.main(Native Method)
And here's my code:
package com.example.dev5.registration.app;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import com.android.volley.Request.Method;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.example.dev5.registration.app.helper.SQLiteHandler;
import com.example.dev5.registration.app.helper.SessionManager;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.HashMap;
import java.util.Map;
public class RegisterActivity extends Activity {
private static final String TAG = RegisterActivity.class.getSimpleName();
private Button btnRegister;
private Button btnLinkToLogin;
private EditText inputFullName;
private EditText inputEmail;
private EditText inputPassword;
private ProgressDialog pDialog;
private SessionManager session;
private SQLiteHandler db;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_register);
inputFullName = (EditText) findViewById(R.id.name);
inputEmail = (EditText) findViewById(R.id.email);
inputPassword = (EditText) findViewById(R.id.password);
btnRegister = (Button) findViewById(R.id.btnRegister);
btnLinkToLogin = (Button) findViewById(R.id.btnLinkToLoginScreen);
// Progress dialog
pDialog = new ProgressDialog(this);
pDialog.setCancelable(false);
// Session manager
session = new SessionManager(getApplicationContext());
// SQLite database handler
db = new SQLiteHandler(getApplicationContext());
// Check if user is already logged in or not
if (session.isLoggedIn()) {
// User is already logged in. Take him to main activity
Intent intent = new Intent(RegisterActivity.this,
MainActivity.class);
startActivity(intent);
finish();
}
// Register Button Click event
btnRegister.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
String name = inputFullName.getText().toString();
String email = inputEmail.getText().toString();
String password = inputPassword.getText().toString();
if (!name.isEmpty() && !email.isEmpty() && !password.isEmpty()) {
registerUser(name, email, password);
} else {
Toast.makeText(getApplicationContext(),
"Please enter your details!", Toast.LENGTH_LONG)
.show();
}
}
});
// Link to Login Screen
btnLinkToLogin.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(),
LoginActivity.class);
startActivity(i);
finish();
}
});
}
/**
* Function to store user in MySQL database will post params(tag, name,
* email, password) to register url
* */
private void registerUser(final String name, final String email,
final String password) {
// Tag used to cancel the request
String tag_string_req = "req_register";
pDialog.setMessage("Registering ...");
showDialog();
StringRequest strReq = new StringRequest(Method.POST,
AppConfig.URL_REGISTER, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
Log.d(TAG, "Register Response: " + response);
hideDialog();
try {
JSONObject jObj = new JSONObject(response);
boolean error = jObj.getBoolean("error");
if (!error) {
// User successfully stored in MySQL
// Now store the user in sqlite
String uid = jObj.getString("uid");
JSONObject user = jObj.getJSONObject("user");
String name = user.getString("name");
String email = user.getString("email");
String created_at = user
.getString("created_at");
// Inserting row in users table
db.addUser(name, email, uid, created_at);
// Launch login activity
Intent intent = new Intent(
RegisterActivity.this,
LoginActivity.class);
startActivity(intent);
finish();
} else {
// Error occurred in registration. Get the error
// message
String errorMsg = jObj.getString("error_msg");
Toast.makeText(getApplicationContext(),
errorMsg, Toast.LENGTH_LONG).show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.e(TAG, "Registration Error: " + error.getMessage());
Toast.makeText(getApplicationContext(),
error.getMessage(), Toast.LENGTH_LONG).show();
hideDialog();
}
}) {
@Override
protected Map<String, String> getParams() {
// Posting params to register url
Map<String, String> params = new HashMap<String, String>();
params.put("tag", "register");
params.put("name", name);
params.put("email", email);
params.put("password", password);
return params;
}
};
// Adding request to request queue
AppController.getInstance().addToRequestQueue(strReq, tag_string_req);
}
private void showDialog() {
if (!pDialog.isShowing())
pDialog.show();
}
private void hideDialog() {
if (pDialog.isShowing())
pDialog.dismiss();
}
}
Can anyone help explain it?
This error happens for multiple reasons. One example is here. If suppose the server returns the error Page not found - 404. Then there is a HTML page. So your json not able to parse it.
The solution is you need to check your response returns from the server.
Edit 1:
You need to check your response before you parse your json there is one tool called POSTMAN try this.