Question

I have problem. I have this code, and I can`t add session.
This is file for login.

    package com.example.netjson;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import com.example.netjson.library.UserFunctions;

public class DashboardActivity extends Activity {
    UserFunctions userFunctions;
    Button btnLogout;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        /**
         * Dashboard Screen for the application
         * */
        // Check login status in database
        userFunctions = new UserFunctions();
        if(userFunctions.isUserLoggedIn(getApplicationContext())){
       // user already logged in show databoard
            setContentView(R.layout.dashboard);
            btnLogout = (Button) findViewById(R.id.btnLogout);

            btnLogout.setOnClickListener(new View.OnClickListener() {

                public void onClick(View arg0) {
                    // TODO Auto-generated method stub
                    userFunctions.logoutUser(getApplicationContext());
                    Intent login = new Intent(getApplicationContext(), LoginActivity.class);
                    login.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                    startActivity(login);
                    // Closing dashboard screen
                    finish();
                }
            });

        }else{
            // user is not logged in show login screen
            Intent login = new Intent(getApplicationContext(), LoginActivity.class);
            login.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
            startActivity(login);
            // Closing dashboard screen
            finish();
        }
    }
}

This file is login panel:

package com.example.netjson;

    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.netjson.library.DatabaseHandler;
    import com.example.netjson.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);

            SessionManager session;

            // 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();
                    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("Zły login lub hasło!");
                            }
                        }
                    } 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();
                }
            });
        }
    }

i don`t know what this is ;D

    package com.example.netjson.library;

import java.util.HashMap;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;

public class DatabaseHandler extends SQLiteOpenHelper {


    Editor editor;

    // All Static variables
    // Database Version
    private static final int DATABASE_VERSION = 1;

    // Database Name
    private static final String DATABASE_NAME = "android_api";

    // Login table name
    private static final String TABLE_LOGIN = "login";

    // Login Table Columns names
    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "name";
    private static final String KEY_EMAIL = "email";
    private static final String KEY_UID = "uid";
    private static final String KEY_CREATED_AT = "created_at";

    public DatabaseHandler(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    // Creating Tables
    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_LOGIN_TABLE = "CREATE TABLE " + TABLE_LOGIN + "("
                + KEY_ID + " INTEGER PRIMARY KEY,"
                + KEY_NAME + " TEXT,"
                + KEY_EMAIL + " TEXT UNIQUE,"
                + KEY_UID + " TEXT,"
                + KEY_CREATED_AT + " TEXT" + ")";
        db.execSQL(CREATE_LOGIN_TABLE);
    }

    // Upgrading database
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_LOGIN);

        // Create tables again
        onCreate(db);
    }

    /**
     * Storing user details in database
     * */
    public void createLoginSession(String email, String name)
    {

         // Storing name in pref
         editor.putString(KEY_NAME, name);
         // Storing email in pref
         editor.putString(KEY_EMAIL, email);
         // commit changes
         editor.commit();
    }

    public void addUser(String name, String email, String uid, String created_at) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(KEY_NAME, name); // Name
        values.put(KEY_EMAIL, email); // Email
        values.put(KEY_UID, uid); // Email
        values.put(KEY_CREATED_AT, created_at); // Created At

        // Inserting Row
        db.insert(TABLE_LOGIN, null, values);
        db.close(); // Closing database connection
    }

    /**
     * Getting user data from database
     * */
    public HashMap<String, String> getUserDetails(){
        HashMap<String,String> user = new HashMap<String,String>();
        String selectQuery = "SELECT  * FROM " + TABLE_LOGIN;

        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);
        // Move to first row
        cursor.moveToFirst();
        if(cursor.getCount() > 0){
            user.put("name", cursor.getString(1));
            user.put("email", cursor.getString(2));
            user.put("uid", cursor.getString(3));
            user.put("created_at", cursor.getString(4));
        }
        cursor.close();
        db.close();
        // return user
        return user;
    }

    /**
     * Getting user login status
     * return true if rows are there in table
     * */
    public int getRowCount() {
        String countQuery = "SELECT  * FROM " + TABLE_LOGIN;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(countQuery, null);
        int rowCount = cursor.getCount();
        db.close();
        cursor.close();

        // return row count
        return rowCount;
    }

    /**
     * Re crate database
     * Delete all tables and create them again
     * */
    public void resetTables(){
        SQLiteDatabase db = this.getWritableDatabase();
        // Delete All Rows
        db.delete(TABLE_LOGIN, null, null);
        db.close();
    }

}

App good login from my forum but i don`t know how add session from java, Thanks for help.

Answer 1

Is your createLoginSession function throwing a NullPointerException? You never initialize editor to point to your SharedPreference where you are storing your session information. If that is the case, you would initialize it as follows:

SharedPreference sharedPreference = getSharedPreferences("your key here", MODE_PRIVATE);
editor = sharedPreference.edit();