Use SharedPreferences in Android

Introduction

 

In this article, we will learn how to develop “remember me check” with functionality in Android.

• In Android usually, we need to persist user session credentials in our application where user session credentials contain the username, email, password and so on.
   
• Using SharedPreferences we can store application preferences data persistently.
   
• In other words, data won't be lost until the application is uninstalled because the preferences data can be stored as key/value pairs and are available across all the Activities of the application or to a specific Activity. 
   
• Application preferences data will be available even when the device starts or stops (the user closes the app and re-open it).
   
• SharedPreferences is used to store primitive data-types

Boolean, float, int, long, string

 

SharedPreferences can be used to store data across all the applications or to the specific activity.

1. getSharedPreferences()- Preferences persisted across all over the application by the name passed to it as a first argument.
    
2. getPreferences()- Preferences persisted for a specific Activity so there is no need to specify the name since there will be only one file for the activity.

For instance-

private SharedPreferences savePreferences;
savePreferences = getSharedPreferences("savePrefs", 0);

Instead of 0 we can use Context.MODE_PRIVATE.

 

We can store as many preferences as we want for our application and all of them will continue to be saved in the savePrefs.xml file because we gave the name “savePrefs” in getSharedPreferences.

 

The savePrefs.xml file is usually located at,

/data/data/[package name]/shared_prefs/savePrefs.xml

Also we can browse it in the File Explorer in the DDMS view.

 

For instance,

 

 

1. Setting or Updating Preferences

 

To set primitive data, Sharedpreferences has some methods, for instance,

putBoolean(), putInt(), putFloat(), putString() and so on.

Method

private SharedPreferences savePreferences;
private SharedPreferences.Editor savePrefsEditor;
savePreferences = getSharedPreferences("savePrefs", 0);
savePrefsEditor = savePreferences.edit();

//If remember me checkbox is checked
if (saveDetailsCheck.isChecked()) {
    //Set the data
    savePrefsEditor.putBoolean("saveLogin", true);
    savePrefsEditor.putString("username", username);
    savePrefsEditor.putString("password", email);
    //Commit the changes
    savePrefsEditor.commit();
    Toast.makeText(getApplicationContext(), "Your details have been saved.", Toast.LENGTH_LONG).show();
}

2. Fetching Preferences

 

For fetching purposes, the object of SharedPreferences is directly used. There is no need for SharedPreferences.Editor.

 

There are the following methods,

getBoolean(), getFloat(), getInt(), getLong(), getString()

Method

private Boolean saveLogin;
saveLogin = savePreferences.getBoolean("saveLogin", false);
if (saveLogin == true)
{
   UserName.setText(savePreferences.getString("username", ""));
   Email.setText(savePreferences.getString("password", ""));
   saveDetailsCheck.setChecked(true);
}

Note- Get methods to have two arguments where the first is the name of the key whereas the second one is the default value to return if the preference does not exist.

 

3. Clear Preferences

//Clear Shared Preferences
savePrefsEditor.clear();
savePrefsEditor.commit();

Source Code

MainActivity.java

package com.example.loginpreferencesdemo;

import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {
    EditText UserName, Email;
    Button Save;
    String username;
    String email;

    private CheckBox saveDetailsCheck;
    private SharedPreferences savePreferences;
    private SharedPreferences.Editor savePrefsEditor;
    private Boolean saveLogin;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.fragment_main);

        UserName = (EditText) findViewById(R.id.editText1);
        Email = (EditText) findViewById(R.id.editText2);
        Save = (Button) findViewById(R.id.button1);

        saveDetailsCheck = (CheckBox) findViewById(R.id.checkBox1);

        savePreferences = getSharedPreferences("savePrefs", 0);
        savePrefsEditor = savePreferences.edit();

        saveLogin = savePreferences.getBoolean("saveLogin", false);
        if (saveLogin == true)

        {
            UserName.setText(savePreferences.getString("username", ""));
            Email.setText(savePreferences.getString("password", ""));
            saveDetailsCheck.setChecked(true);
        }

        Save.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                username = UserName.getText().toString();
                email = Email.getText().toString();

                if (saveDetailsCheck.isChecked()) {
                    savePrefsEditor.putBoolean("saveLogin", true);
                    savePrefsEditor.putString("username", username);
                    savePrefsEditor.putString("password", email);
                    savePrefsEditor.commit();
                    Toast.makeText(getApplicationContext(), "Your details have been saved.", Toast.LENGTH_LONG).show();

                } else {

                    savePrefsEditor.clear();
                    savePrefsEditor.commit();

                }
            }
        });
    }

}

fragment_main.xml

<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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.loginpreferencesdemo.MainActivity$PlaceholderFragment" >
    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Shared Preferences Demo By Abhijeet" />
    <EditText
        android:id="@+id/editText1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/textView1"
        android:layout_below="@+id/textView1"
        android:layout_marginTop="60dp"
        android:ems="10"
        android:hint="UserName" ></EditText>
    <EditText
        android:id="@+id/editText2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/editText1"
        android:layout_below="@+id/editText1"
        android:layout_marginTop="26dp"
        android:ems="10"
        android:hint="Email ID" />
    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/editText2"
        android:layout_below="@+id/editText2"
        android:layout_marginTop="34dp"
        android:text="Save Details" />
    <CheckBox
        android:id="@+id/checkBox1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/editText2"
        android:layout_below="@+id/editText2"
        android:text="Remember Me" />
</RelativeLayout>

Output

 

Before doing that remember to check:

 

 

After remember to check: