error while connecting to sql db from android

Question

I have made database and table at byethost server, generated apk of the code i saw from a tutorial(http://www.androidhive.info/2012/01/android-login-and-registration-with-php-mysql-and-sqlite/) and then installed it on my device. but whenever i try to register, i only get an error message that is a part of UI. and when i try to click the login button in the login page, the app crashes.

code for layout:

<LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:padding="10dip" >
    <!--  View Title Label -->
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="10dip"
        android:text="LOGIN"
        android:textSize="25dip"
        android:textStyle="bold" />
    <!--  Email Label -->
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Email" />
    <!--  Email TextField -->
    <EditText
        android:id="@+id/loginEmail"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />

    <!--  Password Label -->
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="15dip"
        android:text="Password" />
    <!--  Password TextField -->
    <EditText
        android:id="@+id/loginPassword"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:password="true" />

    <!--  Error message -->
    <TextView android:id="@+id/login_error"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:textColor="#e30000"
                android:padding="10dip"
                android:textStyle="bold"/>
    <!--  Login Button -->        
    <Button
        android:id="@+id/btnLogin"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dip"
        android:text="Login" />
     <!--  Link to Registration Screen -->
     <Button
        android:id="@+id/btnLinkToRegisterScreen"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="40dip"
        android:background="@null"
        android:text="I don&apos;t have account. Register Me!"
        android:textColor="#21dbd4"
        android:textStyle="bold" />
     </LinearLayout>

    </ScrollView>

the code for the java file :

import java.util.HashMap;

import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
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.TextView;

import com.example.androidhive.library.DatabaseHandler;
 import com.example.androidhive.library.UserFunctions;

public class LoginActivity extends Activity {
Button btnLogin;
Button btnLinkToRegister;
EditText inputEmail;
EditText inputPassword;
TextView loginErrorMsg;

// JSON Response node names
private static String KEY_SUCCESS = "success";
private static String KEY_ERROR = "error";
private static String KEY_ERROR_MSG = "error_msg";
private static String KEY_UID = "uid";
private static String KEY_NAME = "name";
private static String KEY_EMAIL = "email";
private static String KEY_CREATED_AT = "created_at";

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login);

    // Importing all assets like buttons, text fields
    inputEmail = (EditText) findViewById(R.id.loginEmail);
    inputPassword = (EditText) findViewById(R.id.loginPassword);
    btnLogin = (Button) findViewById(R.id.btnLogin);
    btnLinkToRegister = (Button) findViewById(R.id.btnLinkToRegisterScreen);
    loginErrorMsg = (TextView) findViewById(R.id.login_error);

    // Login button Click Event
    btnLogin.setOnClickListener(new View.OnClickListener() {

        public void onClick(View view) {
            String email = inputEmail.getText().toString();
            String password = inputPassword.getText().toString();
            UserFunctions userFunction = new UserFunctions();
            Log.d("Button", "Login");
            JSONObject json = userFunction.loginUser(email, password);

            // check for login response
            try {
                if (json.getString(KEY_SUCCESS) != null) {
                    loginErrorMsg.setText("");
                    String res = json.getString(KEY_SUCCESS); 
                    if(Integer.parseInt(res) == 1){
                        // user successfully logged in
                        // Store user details in SQLite Database
                        DatabaseHandler db = new DatabaseHandler(getApplicationContext());
                        JSONObject json_user = json.getJSONObject("user");

                        // Clear all previous data in database
                        userFunction.logoutUser(getApplicationContext());
                        db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));                                                                                  // Launch Dashboard Screen
                        Intent dashboard = new Intent(getApplicationContext(), DashboardActivity.class);

                        // Close all views before launching Dashboard
                        dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                        startActivity(dashboard);

                        // Close Login Screen
                        finish();
                    }else{
                        // Error in login
                        loginErrorMsg.setText("Incorrect username/password");
                    }
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    });

    // Link to Register Screen
    btnLinkToRegister.setOnClickListener(new View.OnClickListener() {

        public void onClick(View view) {
            Intent i = new Intent(getApplicationContext(),
                    RegisterActivity.class);
            startActivity(i);
            finish();
        }
    });
   }
  }

edit : logcat when i press login button

07-30 15:32:15.488: I/Choreographer(867): Skipped 81 frames!  The application may be doing too much work on its main thread.
07-30 15:32:31.938: D/Button(867): Login
07-30 15:32:35.650: E/JSON(867): No database selected
07-30 15:32:35.670: E/JSON Parser(867): Error parsing data org.json.JSONException: Value No of type java.lang.String cannot be converted to JSONObject
07-30 15:32:35.679: D/AndroidRuntime(867): Shutting down VM
07-30 15:32:35.690: W/dalvikvm(867): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
07-30 15:32:35.753: E/AndroidRuntime(867): FATAL EXCEPTION: main
07-30 15:32:35.753: E/AndroidRuntime(867): java.lang.NullPointerException
07-30 15:32:35.753: E/AndroidRuntime(867):  at com.example.androidhive.LoginActivity$1.onClick(LoginActivity.java:65)
07-30 15:32:35.753: E/AndroidRuntime(867):  at android.view.View.performClick(View.java:4204)
07-30 15:32:35.753: E/AndroidRuntime(867):  at android.view.View$PerformClick.run(View.java:17355)
07-30 15:32:35.753: E/AndroidRuntime(867):  at android.os.Handler.handleCallback(Handler.java:725)
07-30 15:32:35.753: E/AndroidRuntime(867):  at android.os.Handler.dispatchMessage(Handler.java:92)
07-30 15:32:35.753: E/AndroidRuntime(867):  at android.os.Looper.loop(Looper.java:137)
07-30 15:32:35.753: E/AndroidRuntime(867):  at android.app.ActivityThread.main(ActivityThread.java:5041)
07-30 15:32:35.753: E/AndroidRuntime(867):  at java.lang.reflect.Method.invokeNative(Native Method)
07-30 15:32:35.753: E/AndroidRuntime(867):  at java.lang.reflect.Method.invoke(Method.java:511)
07-30 15:32:35.753: E/AndroidRuntime(867):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
07-30 15:32:35.753: E/AndroidRuntime(867):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
07-30 15:32:35.753: E/AndroidRuntime(867):  at dalvik.system.NativeStart.main(Native Method)

tutorial i referred : http://www.androidhive.info/2012/01/android-login-and-registration-with-php-mysql-and-sqlite/ — Akash, Jul 30 '14 at 15:24
i tried it on a device after building it, does it also give an error log? or should i run it in an emulator? — Akash, Jul 30 '14 at 15:26
Are you doing USB emulation from Eclipse? If yes, in Eclipse go in Window > Show View > Others > LogCat. When something happens while you app is running it'll be show in the LogCat. — Jonas452, Jul 30 '14 at 15:28
i can run it on a VM, but i am unsure if it can connect to the database froma VM. can it connect? — Akash, Jul 30 '14 at 15:29
Do the USB Emulation from Eclipse, it's easer and better them generating the apk, so you can use the LogCat. And I don't think that'll connect. — Jonas452, Jul 30 '14 at 15:32
Here is a tutorial of USB Emulation: http://developer.android.com/tools/building/building-eclipse.html — Jonas452, Jul 30 '14 at 15:33
Use the USB Emulation and the LogCat and make the error happens so he can return you a exception, and then we can help you. — Jonas452, Jul 30 '14 at 15:33

score 0 · Answer 1 · answered Jul 30 '14 at 15:43

First, you should learn more about AsyncTask. Here is a tutorial: http://www.vogella.com/tutorials/AndroidBackgroundProcessing/article.html

Is not good to do that kind of work at the UI Thread.

And your JSON code has to improve. Here is other tutorial: http://www.vogella.com/tutorials/AndroidJSON/article.html

Try to create a class that'll make the connections for your and get the JSONObject from the URL that you pass. You have to deal with the exception.

error while connecting to sql db from android

1 Answers1