Android Shared Preferences with Examples

  Keywords : Android shared preferences to store and retrieve data in key value pair and that values persist across user sessions, Android shared preferences to store primitive data types such as int etc

Here we will learn shared preferences in android with examples, how to use android shared preferences to store and retrieve the values while logging into the application and clear or delete the values from shared preferences file whenever the user clicks on logout button in android application with examples.

Android Shared Preferences

In android, Shared Preferences are used to save and retrieve the primitive data types (integer, float, Boolean, string, long) data in the form of key-value pair from a file within an apps file structure.

 

Generally, the Shared Preferences object will points to a file that contains a key-value pairs and provides a simple read and write methods to save and retrieve the key-value pairs from a file. 

 

The Shared Preferences file is managed by an android framework and it can be accessed anywhere within the app to read or write data into the file, but it’s not possible to access the file from any other app so it’s secured.

 

The Shared Preferences are useful to store the small collection of key-values such as user’s login information, app preferences related to users, etc. to maintain the state of app, next time when they login again to the app.

Handle a Shared Preferences

In android, we can save the preferences data either in single or multiple files based on our requirements.

 

In case if we use single file to save the preferences, then we need to use getPreferences() method to get the values from Shared Preferences file and for multiple files we need to call a getSharedPreferences() method and pass a file name as a parameter.

 

MethodDescription
getPreferences() This method is for activity level preferences and each activity will have it's own preference file and by default this method retrieves a default shared preference file that belongs to the activity.
getSharedPreferences() This method is useful to get the values from multiple shared preference files by passing the name as parameter to identify the file. We can call this from any Context in our app..

Following are the different ways to initialize the Shared Preferences in our application.

 

If we are using single shared preference file for our activity, then we need to initialize the SharedPreferences object by using getPreferences() method like as shown below.

 

SharedPreferences sharedPref = getPreferences(Context.MODE_PRIVATE);

In case, if we are using multiple shared preference files, then we need to initialize the SharedPreferences object by using getSharedPreferences() method like as shown below.

 

SharedPreferences sharedPref = getSharedPreferences("filename1",Context.MODE_PRIVATE);

Here, the name “filename1” is the preference file, which want to read the values based on our requirements and the context mode MODE_PRIVATE, will make sure that the file can be accessed only within our application.

Write to Shared Preferences

To store a data in shared preference file, we need an editor to edit and save the changes in SharedPreferences object. Following is the code snippet to store the data in shared preference file using editor.

 

SharedPreferences sharedPref = getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putBoolean(
"keyname",true);
editor.putString(
"keyname","string value");
editor.putInt(
"keyname","int value");
editor.putFloat(
"keyname","float value");
editor.putLong(
"keyname","long value");
editor.commit();

If you observe above code snippet, we created a SharedPreferences.Editor by calling the edit() method of SharedPreferences object. We added a primitive data type values such as integer, float, long, string and Boolean by passing the keys and values to the methods putInt(), putString(), etc. based on our requirements. After that, to save all the changes we are calling commit() method.

Read from Shared Preferences

To read or retrieve a values from Shared Preferences file, we need to call a methods such as getInt(), getString(), etc. by providing the key for the value which we want to get like as shown below.

 

SharedPreferences pref = getPreferences(Context.MODE_PRIVATE);
pref.getString(
"keyname",null);
pref.getInt(
"keyname",0);
pref.getFloat(
"keyname",0);
pref.getBoolean(
"keyname",true);
pref.getLong(
"keyname",0);

If you observe above code snippet, we are getting the values from shared preferences using a methods such as getInt(), getFloat(), etc. by providing the key for the value which we want to get.

Deleting from Shared Preferences

To delete a values from Shared Preferences file, we need to call a remove() method by providing the key for the value which we want to delete like as shown below.

 

SharedPreferences pref = getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = pref.edit();
editor.remove(
"keyname");
editor.commit();

If you observe above code snippet, we are deleting the values from shared preferences using a method called remove() by providing the key for the value which we want to delete and committing the changes to shared preferences file using commit() method.

Clearing from Shared Preferences

We can clear all the data from Shared Preferences file using clear() method like as shown below.

 

SharedPreferences pref = getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = pref.edit();
editor.clear();
editor.commit();

If you observe above code snippet, we are clearing all the values from shared preferences using a method called clear() and committing the changes to shared preferences file using commit() method.

 

Now we will see how to store and retrieve primitive data type key-value pairs in shared preferences file using SharedPreferences object in android application with examples.

Android Shared Preferences Example

Following is the example of storing and retrieving the primitive data type values from shared preferences file using SharedPreferences.

 

Create a new android application using android studio and give names as SharedPreferencesExample. In case if you are not aware of creating an app in android studio check this article Android Hello World App.

 

Once we create an application, open activity_main.xml file from \res\layout folder path and write the code like as shown below.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   
android:orientation="vertical" android:layout_width="match_parent"
   
android:layout_height="match_parent">
    <
TextView
       
android:id="@+id/fstTxt"
       
android:layout_width="wrap_content"
       
android:layout_height="wrap_content"
       
android:layout_marginLeft="100dp"
       
android:layout_marginTop="150dp"
       
android:text="UserName" />
    <
EditText
       
android:id="@+id/txtName"
       
android:layout_width="wrap_content"
       
android:layout_height="wrap_content"
       
android:layout_marginLeft="100dp"
       
android:ems="10"/>
    <
TextView
       
android:id="@+id/secTxt"
       
android:layout_width="wrap_content"
       
android:layout_height="wrap_content"
       
android:text="Password"
       
android:layout_marginLeft="100dp" />
    <
EditText
        
android:id="@+id/txtPwd"
       
android:inputType="textPassword"
       
android:layout_width="wrap_content"
       
android:layout_height="wrap_content"
       
android:layout_marginLeft="100dp"
       
android:ems="10" />
    <
Button
       
android:id="@+id/btnLogin"
       
android:layout_width="wrap_content"
       
android:layout_height="wrap_content"
       
android:layout_marginLeft="100dp"
       
android:text="Login" />
</
LinearLayout>

Now we will create another layout resource file details.xml in \res\layout path to get the first activity (activity_main.xml) details in second activity file for that right click on your layout folder à Go to New à select Layout Resource File and give name as details.xml.

 

Once we create a new layout resource file details.xml, open it and write the code like as shown below

details.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   
android:orientation="vertical" android:layout_width="match_parent"
   
android:layout_height="match_parent">
    <
TextView
       
android:layout_width="wrap_content"
       
android:layout_height="wrap_content"
       
android:id="@+id/resultView"
       
android:layout_gravity="center"
       
android:layout_marginTop="170dp"
       
android:textSize="20dp"/>
    <
Button
       
android:id="@+id/btnLogOut"
       
android:layout_width="wrap_content"
       
android:layout_height="wrap_content"
       
android:layout_gravity="center"
       
android:layout_marginTop="20dp"
       
android:text="Log Out" />
</
LinearLayout>

Now open your main activity file MainActivity.java from \java\com.tutlane.sharedpreferencesexample path and write the code like as shown below

MainActivity.java

package com.tutlane.sharedpreferencesexample;
import android.content.Intent;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    EditText
uname, pwd;
    Button
loginBtn;
    SharedPreferences
pref;
    Intent
intent;
   
@Override
   
protected void onCreate(Bundle savedInstanceState) {
       
super.onCreate(savedInstanceState);
        setContentView(R.layout.
activity_main);
       
uname = (EditText)findViewById(R.id.txtName);
       
pwd = (EditText)findViewById(R.id.txtPwd);
       
loginBtn = (Button)findViewById(R.id.btnLogin);
       
pref = getSharedPreferences("user_details",MODE_PRIVATE);
       
intent = new Intent(MainActivity.this,DetailsActivity.class);
       
if(pref.contains("username") && pref.contains("password")){
            startActivity(
intent);
        }
       
loginBtn.setOnClickListener(new View.OnClickListener() {
           
@Override
           
public void onClick(View v) {
                String username =
uname.getText().toString();
                String password =
pwd.getText().toString();
                
if(username.equals("suresh") && password.equals("dasari")){
                    SharedPreferences.Editor editor =
pref.edit();
                    editor.putString(
"username",username);
                    editor.putString(
"password",password);
                    editor.commit();
                    Toast.makeText(getApplicationContext(),
"Login Successful",Toast.LENGTH_SHORT).show();
                    startActivity(
intent);
                }
               
else
               
{
                    Toast.makeText(getApplicationContext(),
"Credentials are not valid",Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}

If you observe above code, we are checking whether the entered username and password details matching or not based on that we are saving the details in shared preferences file and redirecting the user to another activity.

 

Now we will create another activity file DetailsActivity.java in \java\com.tutlane.sharedpreferencesexample path to show the details from shared preference file for that right click on your application folder à Go to New à select Java Class and give name as DetailsActivity.java.

 

Once we create a new activity file DetailsActivity.java, open it and write the code like as shown below

DetailsActivity.java

package com.tutlane.sharedpreferencesexample;
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.TextView;

/**
 * Created by tutlane on 03-01-2018.
 */

public class DetailsActivity extends AppCompatActivity {
    SharedPreferences
prf;
    Intent
intent;
   
@Override
   
protected void onCreate(Bundle savedInstanceState) {
       
super.onCreate(savedInstanceState);
        setContentView(R.layout.
details);
        TextView result = (TextView)findViewById(R.id.
resultView);
        Button btnLogOut = (Button)findViewById(R.id.
btnLogOut);
       
prf = getSharedPreferences("user_details",MODE_PRIVATE);
       
intent = new Intent(DetailsActivity.this,MainActivity.class);
        result.setText(
"Hello, "+prf.getString("username",null));
        btnLogOut.setOnClickListener(
new View.OnClickListener() {
           
@Override
           
public void onClick(View v) {
                SharedPreferences.Editor editor =
prf.edit();
                editor.clear();
                editor.commit();
                startActivity(
intent);
            }
        });
    }
}

Now we need to add this newly created activity in AndroidManifest.xml file in like as shown below.

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   
package="com.tutlane.sharedpreferencesexample">
    <
application
       
android:allowBackup="true"
       
android:icon="@mipmap/ic_launcher"
       
android:label="@string/app_name"
       
android:roundIcon="@mipmap/ic_launcher_round"
       
android:supportsRtl="true"
       
android:theme="@style/AppTheme">
        <
activity android:name=".MainActivity">
            <
intent-filter>
                <
action android:name="android.intent.action.MAIN" />
                <
category android:name="android.intent.category.LAUNCHER" />
            </
intent-filter>
        </
activity>
        <
activity android:name=".DetailsActivity" android:label="Shared Preferences - Details"></activity>
    </
application>
</
manifest>

If you observe above example, we are checking whether the entered user details matching or not based on that we are saving the user details in shared preferences file and redirecting the user to another activity file (DetailsActivity.java) to show the users details and added all the activities in AndroidManifest.xml file.

Output of Android Shared Preferences Example

When we run above example in android emulator we will get a result like as shown below

 

Android Shared Preferences Example Result

 

If you observe above result, the entered username and password matches then we are redirecting user to another activity file to show the user details from shared preferences file. After that, if we click on Logout button, it will clear all the values in shared preferences file and it will redirect user to login page.

 

This is how we can use Shared Preferences in android applications to store and retrieve key-value pair values based on our requirements.