Session are useful when you want to store user data globally through out the application. This can be done in two ways. One is storing them in a global variables and second is storing the data in shared preferences. The problem with storing data in global variable is data will be lost once user closes the application, but storing the data in shared preferences will be persistent even though user closes the application.
Application shared preferences allows you to save and retrieve key, value pair data. Before getting into tutorial, I am giving basic information needed to work with shared preferences.
Initialization
Application shared preferences can be fetched using getSharedPreferences() method.You also need an editor to edit and save the changes in shared preferences. The following code can be used to get application shared preferences.
SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", 0); Editor editor = pref.edit();
Storing Data
You can save data into shared preferences using editor.
All the primitive data types like booleans, floats, ints, longs, and strings are supported. Call editor.commit() in order to save changes to shared preferences.
editor.putBoolean("key_name", true); // Storing boolean - true/false
editor.putString("key_name", "string value"); // Storing string
editor.putInt("key_name", "int value"); // Storing integer
editor.putFloat("key_name", "float value"); // Storing float
editor.putLong("key_name", "long value"); // Storing long
editor.commit(); // commit changes
Retrieving Data
Data can be retrived from saved preferences by calling getString() (For string) method.
Remember this method should be called on Shared Preferences not on Editor.
// returns stored preference value
// If value is not present return second param value - In this case null
pref.getString("key_name", null); // getting String
pref.getInt("key_name", null); // getting Integer
pref.getFloat("key_name", null); // getting Float
pref.getLong("key_name", null); // getting Long
pref.getBoolean("key_name", null); // getting boolean
Clearing / Deleting Data
If you want to delete from shared preferences you can call remove(“key_name”) to delete that particular value.
If you want to delete all the data, call clear()
editor.remove("name"); // will delete key name
editor.remove("email"); // will delete key email
editor.commit(); // commit changes
Following will clear all the data from shared preferences
editor.clear();
editor.commit(); // commit changes
The following is a simple tutorial which will have a login form and a dashboard screen.
At first user will login using login details and once he successfully logged in his credentials (name, email) will be stored in shared preferences.
User Session Management using Shared Preferences
1. Create a new project in Eclipse IDE File ⇒ New ⇒ Android Application Project and fill all the required details
2. I am adding alert dialog manager class to show alert messages while validating the login form. Create a new class and name it as AlertDialogManager.java and paste the following code.
AlertDialogManager.java
package com.nishal.sessions;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
public class AlertDialogManager {
/**
* Function to display simple Alert Dialog
* @param context - application context
* @param title - alert dialog title
* @param message - alert message
* @param status - success/failure (used to set icon)
* - pass null if you don't want icon
* */
public void showAlertDialog(Context context, String title, String message,
Boolean status) {
AlertDialog alertDialog = new AlertDialog.Builder(context).create();
// Setting Dialog Title
alertDialog.setTitle(title);
// Setting Dialog Message
alertDialog.setMessage(message);
if(status != null)
// Setting alert dialog icon
alertDialog.setIcon((status) ? R.drawable.success : R.drawable.fail);
// Setting OK Button
alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
}
});
// Showing Alert Message
alertDialog.show();
}
}
3. I am writing all session related functions in one class to make them available in all activities.
Create a new class named SessionManagement.java and add following lines of code
SessionManagement.java
package com.nishal.sessions;
import java.util.HashMap;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
public class SessionManager {
// Shared Preferences
SharedPreferences pref;
// Editor for Shared preferences
Editor editor;
// Context
Context _context;
// Shared pref mode
int PRIVATE_MODE = 0;
// Sharedpref file name
private static final String PREF_NAME = "AndroidHivePref";
// All Shared Preferences Keys
private static final String IS_LOGIN = "IsLoggedIn";
// User name (make variable public to access from outside)
public static final String KEY_NAME = "name";
// Email address (make variable public to access from outside)
public static final String KEY_EMAIL = "email";
// Constructor
public SessionManager(Context context){
this._context = context;
pref = _context.getSharedPreferences(PREF_NAME, PRIVATE_MODE);
editor = pref.edit();
}
4. In this example i am storing login status, name, email in shared preferences,
so i added a function called createLoginSession(String name, String email) to SessionManagement class. Add the following function to SessionManagement.java.
> This function simply stores login status(true), name, email in shared preferences.
/**
* Create login session
* */
public void createLoginSession(String name, String email){
// Storing login value as TRUE
editor.putBoolean(IS_LOGIN, true);
// Storing name in pref
editor.putString(KEY_NAME, name);
// Storing email in pref
editor.putString(KEY_EMAIL, email);
// commit changes
editor.commit();
}
5.In order to get the stored preferences data, I added a function called getUserDetails() with the following code.
> The following function will read shared preferences and returns user data in HashMap
/**
* Get stored session data
* */
public HashMap<String, String> getUserDetails(){
HashMap<String, String> user = new HashMap<String, String>();
// user name
user.put(KEY_NAME, pref.getString(KEY_NAME, null));
// user email id
user.put(KEY_EMAIL, pref.getString(KEY_EMAIL, null));
// return user
return user;
}
6. To check whether user logged in or not i added a function checkLogin() which you can call in all Activities to check user login status.
> This function simply check user login status from shared preferences and if user is not login it will redirect user to LoginActivity
/**
* Check login method wil check user login status
* If false it will redirect user to login page
* Else won't do anything
* */
public void checkLogin(){
// Check login status
if(!this.isLoggedIn()){
// user is not logged in redirect him to Login Activity
Intent i = new Intent(_context, LoginActivity.class);
// Closing all the Activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
// Add new Flag to start new Activity
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
// Staring Login Activity
_context.startActivity(i);
}
}
7. Add a function called logoutUser() to clear all the data from shared preferences. Call this function when you want to logout the user.
> This function clears all session data and redirect the user to LoginActivity
/**
* Clear session details
* */
public void logoutUser(){
// Clearing all data from Shared Preferences
editor.clear();
editor.commit();
// After logout redirect user to Loing Activity
Intent i = new Intent(_context, LoginActivity.class);
// Closing all the Activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
// Add new Flag to start new Activity
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
// Staring Login Activity
_context.startActivity(i);
}
Final Code
SessionManagement.java
package com.nishal.sessions;
import java.util.HashMap;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
public class SessionManager {
// Shared Preferences
SharedPreferences pref;
// Editor for Shared preferences
Editor editor;
// Context
Context _context;
// Shared pref mode
int PRIVATE_MODE = 0;
// Sharedpref file name
private static final String PREF_NAME = "AndroidHivePref";
// All Shared Preferences Keys
private static final String IS_LOGIN = "IsLoggedIn";
// User name (make variable public to access from outside)
public static final String KEY_NAME = "name";
// Email address (make variable public to access from outside)
public static final String KEY_EMAIL = "email";
// Constructor
public SessionManager(Context context){
this._context = context;
pref = _context.getSharedPreferences(PREF_NAME, PRIVATE_MODE);
editor = pref.edit();
}
/**
* Create login session
* */
public void createLoginSession(String name, String email){
// Storing login value as TRUE
editor.putBoolean(IS_LOGIN, true);
// Storing name in pref
editor.putString(KEY_NAME, name);
// Storing email in pref
editor.putString(KEY_EMAIL, email);
// commit changes
editor.commit();
}
/**
* Check login method wil check user login status
* If false it will redirect user to login page
* Else won't do anything
* */
public void checkLogin(){
// Check login status
if(!this.isLoggedIn()){
// user is not logged in redirect him to Login Activity
Intent i = new Intent(_context, LoginActivity.class);
// Closing all the Activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
// Add new Flag to start new Activity
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
// Staring Login Activity
_context.startActivity(i);
}
}
/**
* Get stored session data
* */
public HashMap<String, String> getUserDetails(){
HashMap<String, String> user = new HashMap<String, String>();
// user name
user.put(KEY_NAME, pref.getString(KEY_NAME, null));
// user email id
user.put(KEY_EMAIL, pref.getString(KEY_EMAIL, null));
// return user
return user;
}
/**
* Clear session details
* */
public void logoutUser(){
// Clearing all data from Shared Preferences
editor.clear();
editor.commit();
// After logout redirect user to Loing Activity
Intent i = new Intent(_context, LoginActivity.class);
// Closing all the Activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
// Add new Flag to start new Activity
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
// Staring Login Activity
_context.startActivity(i);
}
/**
* Quick check for login
* **/
// Get Login State
public boolean isLoggedIn(){
return pref.getBoolean(IS_LOGIN, false);
}
}
8. Until now we are done creating Session Management class and now we are going to learn how to use this class in your application. For this create a simple login form asking username, password.
Create a layout xml file and a class to create login form. Name the xml file as activity_login.xmland class name as LoginActivity.java
activity_login.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="10dip">
<!-- Email Label -->
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Username (Enter 'test')"
android:singleLine="true"
android:layout_marginBottom="5dip"/>
<!-- Email input text -->
<EditText android:id="@+id/txtUsername"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="10dip"/>
<!-- Password Label -->
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Password (Enter 'test')"
android:layout_marginBottom="5dip"/>
<!-- Password input text -->
<EditText android:id="@+id/txtPassword"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="20dip"
android:password="true"
android:singleLine="true"/>
<!-- Login button -->
<Button android:id="@+id/btnLogin"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Login"/>
</LinearLayout>
For testing purpose i am checking username, password as test, test.
Once the user enters correct login details a session will be created by
calling session.createLoginSession(“Android Hive”, “anroidhive@gmail.com”) and user is redirected toMainActivity.
LoginActivity.java
package com.nishal.sessions;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class LoginActivity extends Activity {
// Email, password edittext
EditText txtUsername, txtPassword;
// login button
Button btnLogin;
// Alert Dialog Manager
AlertDialogManager alert = new AlertDialogManager();
// Session Manager Class
SessionManager session;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
// Session Manager
session = new SessionManager(getApplicationContext());
// Email, Password input text
txtUsername = (EditText) findViewById(R.id.txtUsername);
txtPassword = (EditText) findViewById(R.id.txtPassword);
Toast.makeText(getApplicationContext(), "User Login Status: " + session.isLoggedIn(), Toast.LENGTH_LONG).show();
// Login button
btnLogin = (Button) findViewById(R.id.btnLogin);
// Login button click event
btnLogin.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// Get username, password from EditText
String username = txtUsername.getText().toString();
String password = txtPassword.getText().toString();
// Check if username, password is filled
if(username.trim().length() > 0 && password.trim().length() > 0){
// For testing puspose username, password is checked with sample data
// username = test
// password = test
if(username.equals("test") && password.equals("test")){
// Creating user login session
// For testing i am stroing name, email as follow
// Use user real data
session.createLoginSession("Android Hive", "anroidhive@gmail.com");
// Staring MainActivity
Intent i = new Intent(getApplicationContext(), MainActivity.class);
startActivity(i);
finish();
}else{
// username / password doesn't match
alert.showAlertDialog(LoginActivity.this, "Login failed..", "Username/Password is incorrect", false);
}
}else{
// user didn't entered username or password
// Show alert asking him to enter the details
alert.showAlertDialog(LoginActivity.this, "Login failed..", "Please enter username and password", false);
}
}
});
}
}
 
9. After user redirected to MainActivity,
I am getting stored session data by callinggetUserDetails() and displayed in textviews.
> session.checkLogin() is called to check user login status.
Here if user is not login he will be redirected to LoginActivity.java > If user is logged in, user details are fetched by calling session.getUserDetails() and displayed in textviews. > Also I have logout button which invokes a function session.logoutUser() to clear the session data. Layout code for activity_main.xml
activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="10dip">
<!-- Name Label -->
<TextView
android:id="@+id/lblName"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:singleLine="true"
android:layout_marginTop="40dip"
android:layout_marginBottom="10dip"/>
<!-- Email Label -->
<TextView
android:id="@+id/lblEmail"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:singleLine="true"
android:layout_marginBottom="40dip"/>
<!-- Button to show session data -->
<Button android:id="@+id/btnLogout"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Logout"/>
</LinearLayout>
Code for MainActivity.java
package com.nishal.sessions;
import java.util.HashMap;
import android.app.Activity;
import android.os.Bundle;
import android.text.Html;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
// Alert Dialog Manager
AlertDialogManager alert = new AlertDialogManager();
// Session Manager Class
SessionManager session;
// Button Logout
Button btnLogout;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Session class instance
session = new SessionManager(getApplicationContext());
TextView lblName = (TextView) findViewById(R.id.lblName);
TextView lblEmail = (TextView) findViewById(R.id.lblEmail);
// Button logout
btnLogout = (Button) findViewById(R.id.btnLogout);
Toast.makeText(getApplicationContext(), "User Login Status: " + session.isLoggedIn(), Toast.LENGTH_LONG).show();
/**
* Call this function whenever you want to check user login
* This will redirect user to LoginActivity is he is not
* logged in
* */
session.checkLogin();
// get user data from session
HashMap<String, String> user = session.getUserDetails();
// name
String name = user.get(SessionManager.KEY_NAME);
// email
String email = user.get(SessionManager.KEY_EMAIL);
// displaying user data
lblName.setText(Html.fromHtml("Name: <b>" + name + "</b>"));
lblEmail.setText(Html.fromHtml("Email: <b>" + email + "</b>"));
/**
* Logout button click event
* */
btnLogout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// Clear the session data
// This will clear all session data and
// redirect user to LoginActivity
session.logoutUser();
}
});
}
}
10. Open AndroidManifest.xml file, add the following code and run the project.
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.androidhive.sessions"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="Dashboard Screen" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<!-- DashBoard / MainActivity -->
<activity
android:name=".LoginActivity"
android:label="User Login" >
</activity>
</application>
</manifest>
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