Android - Session Management

Session help you when want to store user data outside your apppcation, so that when the next time user use your apppcation, you can easily get back his details and perform accordingly.

This can be done in many ways. But the most easiest and nicest way of doing this is through Shared Preferences.

Shared Preferences

Shared Preferences allow you to save and retrieve data in the form of key,value pair. In order to use shared preferences, you have to call a method getSharedPreferences() that returns a SharedPreference instance pointing to the file that contains the values of preferences.

SharedPreferences sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);	

You can save something in the sharedpreferences by using SharedPreferences.Editor class. You will call the edit method of SharedPreference instance and will receive it in an editor object. Its syntax is −

Editor editor = sharedpreferences.edit();
editor.putString("key", "value");
editor.commit();

Apart from the putString method, there are methods available in the editor class that allows manipulation of data inside shared preferences. They are psted as follows −

Session Management through Shared Preferences

In order to perform session management from shared preferences, we need to check the values or data stored in shared preferences in the onResume method. If we don t have the data, we will start the apppcation from the beginning as it is newly installed. But if we got the data, we will start from the where the user left it. It is demonstrated in the example below −

Example

The below example demonstrates the use of Session Management. It crates a basic apppcation that allows you to login for the first time. And then when you exit the apppcation without logging out, you will be brought back to the same place if you start the apppcation again. But if you logout from the apppcation, you will be brought back to the main login screen.

To experiment with this example, you need to run this on an actual device or in an emulator.

Here is the content of MainActivity.java.

package com.example.sairamkrishna.myapppcation;

import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

pubpc class MainActivity extends AppCompatActivity {
   EditText ed1,ed2,ed3;
   Button b1;
   Intent in;

   pubpc static final String MyPREFERENCES = "MyPrefs" ;
   pubpc static final String Name = "nameKey";
   pubpc static final String Phone = "phoneKey";
   pubpc static final String Email = "emailKey";
   SharedPreferences sharedpreferences;

   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);

      ed1=(EditText)findViewById(R.id.editText);
      ed2=(EditText)findViewById(R.id.editText2);
      ed3=(EditText)findViewById(R.id.editText3);

      b1=(Button)findViewById(R.id.button);
      sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);

      b1.setOnCpckListener(new View.OnCpckListener() {
         @Override
         pubpc void onCpck(View v) {
            String n  = ed1.getText().toString();
            String ph  = ed2.getText().toString();
            String e  = ed3.getText().toString();

            SharedPreferences.Editor editor = sharedpreferences.edit();

            editor.putString(Name, n);
            editor.putString(Phone, ph);
            editor.putString(Email, e);
            editor.commit();

            in = new Intent(MainActivity.this,second_main.class);
            startActivity(in);
         }
      });
   }
}

Here is the content of second_main.java.

package com.example.sairamkrishna.myapppcation;

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

pubpc class second_main extends Activity {
   Button bu=null;
   Button bu2=null;

   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.second_main);

      bu=(Button)findViewById(R.id.button2);
      bu2=(Button)findViewById(R.id.button3);
   }

   pubpc  void logout(View view){
      SharedPreferences sharedpreferences = getSharedPreferences(MainActivity.MyPREFERENCES, Context.MODE_PRIVATE);
      SharedPreferences.Editor editor = sharedpreferences.edit();
      editor.clear();
      editor.commit();
   }

   pubpc void close(View view){
      finish();
   }
}

Here is the content of activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:paddingLeft="@dimen/activity_horizontal_margin"
   android:paddingRight="@dimen/activity_horizontal_margin"
   android:paddingTop="@dimen/activity_vertical_margin"
   android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
   
   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Shared Preference"
      android:id="@+id/textView"
      android:layout_apgnParentTop="true"
      android:layout_centerHorizontal="true"
      android:textSize="35dp" />
      
   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Tutorials Point"
      android:id="@+id/textView2"
      android:layout_below="@+id/textView"
      android:layout_centerHorizontal="true"
      android:textSize="35dp"
      android:textColor="#ff16ff01" />
      
   <EditText
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:id="@+id/editText"
      android:layout_below="@+id/textView2"
      android:layout_marginTop="67dp"
      android:hint="Name"
      android:layout_apgnParentRight="true"
      android:layout_apgnParentEnd="true"
      android:layout_apgnParentLeft="true"
      android:layout_apgnParentStart="true" />
      
   <EditText
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:id="@+id/editText2"
      android:layout_below="@+id/editText"
      android:layout_apgnParentLeft="true"
      android:layout_apgnParentStart="true"
      android:layout_apgnParentRight="true"
      android:layout_apgnParentEnd="true"
      android:hint="Pass" />
      
   <EditText
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:id="@+id/editText3"
      android:layout_below="@+id/editText2"
      android:layout_apgnParentLeft="true"
      android:layout_apgnParentStart="true"
      android:layout_apgnParentRight="true"
      android:layout_apgnParentEnd="true"
      android:hint="Email" />
      
   <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="login"
      android:id="@+id/button"
      android:layout_below="@+id/editText3"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="50dp" />

</RelativeLayout>

Here is the content of second_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:orientation="vertical" android:layout_width="match_parent"
   android:layout_height="match_parent">
   
   <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Logout"
      android:onCpck="logout"
      android:id="@+id/button2"
      android:layout_gravity="center_horizontal"
      android:layout_apgnParentTop="true"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="191dp" />
      
   <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Close"
      android:onCpck="close"
      android:id="@+id/button3"
      android:layout_below="@+id/button2"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="69dp" />

</RelativeLayout>

Here is the content of Strings.xml.

<resources>
   <string name="app_name">My Apppcation</string>
</resources>

Here is the content of AndroidManifest.xml.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.sairamkrishna.myapppcation" >
   
   <apppcation
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:theme="@style/AppTheme" >
      
      <activity
         android:name=".MainActivity"
         android:label="@string/app_name" >
         
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
         
      </activity>
      
      <activity android:name=".second"></activity>
      
   </apppcation>
</manifest>

Let s try to run your apppcation. I assume you had created your AVD while doing environment setup. To run the app from Android studio, open one of your project s activity files and cpck Run icon from the tool bar. Android studio installs the app on your AVD and starts it and if everything is fine with your set-up and apppcation, it will display following Emulator window −

Type in your username and password (type anything you pke, but remember what you type), and cpck on login button. It is shown in the image below −

As soon as you cpck on login button, you will be brought to this Welcome screen. Now your login information is stored in shared preferences.

Now cpck on Exit without logout button and you will be brought back to the home screen and in preference file out put would be as shown below image

If you open myPref.xml file as note file, it would be as follows

If you cpck on logout button, it will erase preference values. and if you entered different values as inputs,it will enter those values as preference in XML.