Android app crashes pressing login button

Question

I am trying to make a simple login screen, which is being loaded correctly is user isn't already logged in. However - pressing "LOGIN" button, crashes the app.

LoginActivity.java

package com.atsdata.flldk;

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.atsdata.flldk.library.DatabaseHandler;
import com.atsdata.flldk.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);
        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();
                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(), MainActivity.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();
                }
            }
        });


    }
}

UserFunctions.java

package com.atsdata.flldk.library;

import java.util.ArrayList;
import java.util.List;

import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONObject;

import android.content.Context;

public class UserFunctions {

    private JSONParser jsonParser;

    // Testing in localhost using wamp or xampp 
    // use http://10.0.2.2/ to connect to your localhost ie http://localhost/
    private static String loginURL = "http://<url-removed>";
    private static String registerURL = "http://<url-removed>";

    private static String login_tag = "login";
    private static String register_tag = "register";

    // constructor
    public UserFunctions(){
        jsonParser = new JSONParser();
    }

    /**
     * function make Login Request
     * @param email
     * @param password
     * */
    public JSONObject loginUser(String email, String password){
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("tag", login_tag));
        params.add(new BasicNameValuePair("email", email));
        params.add(new BasicNameValuePair("password", password));
        JSONObject json = jsonParser.getJSONFromUrl(loginURL, params);
        // return json
        // Log.e("JSON", json.toString());
        return json;
    }

    /**
     * function make Login Request
     * @param name
     * @param email
     * @param password
     * */
    public JSONObject registerUser(String name, String email, String password){
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("tag", register_tag));
        params.add(new BasicNameValuePair("name", name));
        params.add(new BasicNameValuePair("email", email));
        params.add(new BasicNameValuePair("password", password));

        // getting JSON Object
        JSONObject json = jsonParser.getJSONFromUrl(registerURL, params);
        // return json
        return json;
    }

    /**
     * Function get Login status
     * */
    public boolean isUserLoggedIn(Context context){
        DatabaseHandler db = new DatabaseHandler(context);
        int count = db.getRowCount();
        if(count > 0){
            // user logged in
            return true;
        }
        return false;
    }

    /**
     * Function to logout user
     * Reset Database
     * */
    public boolean logoutUser(Context context){
        DatabaseHandler db = new DatabaseHandler(context);
        db.resetTables();
        return true;
    }

}

log cat

03-07 06:58:40.212: D/AndroidRuntime(1440): Shutting down VM
03-07 06:58:40.212: W/dalvikvm(1440): threadid=1: thread exiting with uncaught exception (group=0xb1aa3b90)
03-07 06:58:40.222: E/AndroidRuntime(1440): FATAL EXCEPTION: main
03-07 06:58:40.222: E/AndroidRuntime(1440): Process: com.atsdata.flldk, PID: 1440
03-07 06:58:40.222: E/AndroidRuntime(1440): android.os.NetworkOnMainThreadException
03-07 06:58:40.222: E/AndroidRuntime(1440):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1145)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at java.net.InetAddress.getAllByName(InetAddress.java:214)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at com.atsdata.flldk.library.JSONParser.getJSONFromUrl(JSONParser.java:43)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at com.atsdata.flldk.library.UserFunctions.loginUser(UserFunctions.java:40)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at com.atsdata.flldk.LoginActivity$1.onClick(LoginActivity.java:54)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at android.view.View.performClick(View.java:4424)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at android.view.View$PerformClick.run(View.java:18383)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at android.os.Handler.handleCallback(Handler.java:733)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at android.os.Handler.dispatchMessage(Handler.java:95)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at android.os.Looper.loop(Looper.java:137)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at android.app.ActivityThread.main(ActivityThread.java:4998)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at java.lang.reflect.Method.invokeNative(Native Method)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at java.lang.reflect.Method.invoke(Method.java:515)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
03-07 06:58:40.222: E/AndroidRuntime(1440):     at dalvik.system.NativeStart.main(Native Method)

If anyone can point me in the right direction it would be great. Thanks.

Put your Button `onClick()` code into `AsyncTask (Background)` — M D, Mar 07 '14 at 12:17
Simply pasting the exception into google would have told you whats wrong. — meredrica, Mar 07 '14 at 12:48

score 2 · Accepted Answer · answered Mar 07 '14 at 12:31

You are not allowed to do network communication on the UI main thread. This is to stop your code blocking the UI and it locking up. You need to do the network work on another thread. You should read about AsyncTasks:

http://www.vogella.com/tutorials/AndroidBackgroundProcessing/article.html#concurrency_asynchtask

http://developer.android.com/reference/android/os/AsyncTask.html

score 1 · Answer 2 · answered Mar 07 '14 at 12:31

NetworkOnMainThreadException

This means that you cannot perform network operation in the main thread (like onClick or other methods not used in another thread).

Try to put the code in

public void onClick(View view) {...}

to an AsyncTask

AsyncTask

Android app crashes pressing login button

2 Answers2