CODEWITHSUNDEEP
androidauthenticationsharedpreferences
Hendra Anggrian
Hendra Anggrian

Reputation: 5848

Shared Preferences in Android?

I'm a novice Android developer who are currently trying hard to build a Login Screen.

I need to find the easiest way to store the username and password in 1 class and retrieve it from another class. See Google has provided several ways: http://developer.android.com/guide/topics/data/data-storage.html

which one is the most efficient and easy to code?

thanks!

Upvotes: 4

Views: 3940

Answers (5)

Akhilesh Mani
Akhilesh Mani

Reputation: 3552

For Login screen tasks like storing username and password you can use Shared Preferences. Here I had made custom methods for using shared preferences. Call savePreferences() method and put your Key and Value(as savePreferences() is based on XML), similarly call Load with your Key. And lastly don't forgot to call deletePreferences() on LOGOUT.

/**
 *   Method used to get Shared Preferences */

public SharedPreferences getPreferences() 
{
    return getSharedPreferences(<PREFRENCE_FILE_NAME>, MODE_PRIVATE);
}
/**
 *  Method used to save Preferences */
public void savePreferences(String key, String value) 
{
    SharedPreferences sharedPreferences = getPreferences();
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putString(key, value);
    editor.commit();
}
/**
 *  Method used to load Preferences */
public String loadPreferences(String key) 
{
    try {
        SharedPreferences sharedPreferences = getPreferences();
        String strSavedMemo = sharedPreferences.getString(key, "");
        return strSavedMemo;
    } catch (NullPointerException nullPointerException) 
    {
        Log.e("Error caused at  TelaSketchUtin loadPreferences method",
                ">======>" + nullPointerException);
        return null;
    }
}
/**
 *  Method used to delete Preferences */
public boolean deletePreferences(String key)
{
    SharedPreferences.Editor editor=getPreferences().edit();
    editor.remove(key).commit();
    return false;
}

Upvotes: 4

Hardik Joshi
Hardik Joshi

Reputation: 9507

Define some statics to store the preference file name and the keys you're going to use:

public static final String PREFS_NAME = "MyPrefsFile";
private static final String PREF_USERNAME = "username";
private static final String PREF_PASSWORD = "password";

You'd then save the username and password as follows: 

getSharedPreferences(PREFS_NAME,MODE_PRIVATE)
.edit()
.putString(PREF_USERNAME, username)
.putString(PREF_PASSWORD, password)
.commit();

So you would retrieve them like this: 

SharedPreferences pref = getSharedPreferences(PREFS_NAME,MODE_PRIVATE);   
String username = pref.getString(PREF_USERNAME, null);
String password = pref.getString(PREF_PASSWORD, null);

if (username == null || password == null) {

//Prompt for username and password
}

Alternatively, if you don't want to name a preferences file you can just use the default:

SharedPreferences pref = PreferenceManager.getDefaultSharedPreferences(this);

Upvotes: 4

Yogesh Somani
Yogesh Somani

Reputation: 2624

Many applications may provide a way to capture user preferences on the settings of a specific application or an activity. For supporting this, Android provides a simple set of APIs.

Preferences are typically name value pairs. They can be stored as “Shared Preferences” across various activities in an application (note currently it cannot be shared across processes). Or it can be something that needs to be stored specific to an activity.

Shared Preferences: The shared preferences can be used by all the components (activities, services etc) off the applications.

Activity handled preferences: These preferences can only be used with in the activity and can not be used by other components of the application.

Shared Preferences:

The shared preferences are managed with the help of the getSharedPreferences method of the Context class. The preferences are stored in a default file(1) or you can specify a file name(2) to be used to refer to the preferences.

(1) Here is how you get the instance when you specify the file name

  public static final String PREF_FILE_NAME = "PrefFile";
  SharedPreferences preferences = getSharedPreferences(PREF_FILE_NAME, MODE_PRIVATE);

MODE_PRIVATE is the operating mode for the preferences. It is the default mode and means the created file will be accessed by only the calling application. Other two mode supported are MODE_WORLD_READABLE and MODE_WORLD_WRITEABLE. In MODE_WORLD_READABLE other application can read the created file but can not modify it. In case of MODE_WORLD_WRITEABLE other applications also have write permissions for the created file.

(2) The recommended way is to use by the default mode, without specifying the file name:

  SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);

Finally, once you have the preferences instance, here is how you can retrieve the stored values from the preferences:

   int storedPreference = preferences.getInt("storedInt", 0);

To store values in the preference file SharedPreference.Editor object has to be used. Editor is the nested interface of the SharedPreference class.

   SharedPreferences.Editor editor = preferences.edit();
   editor.putInt("storedInt", storedPreference); // value to store
   editor.commit();

Editor also support methods like remove() and clear() to delete the preference value from the file.

Activity Preferences:

The shared preferences can be used by other application components. But if you do not need to share the preferences with other components and want to have activities private preferences. You can do that with the help of getPreferences() method of the activity. The getPreference method uses the getSharedPreferences() method with the name of the activity class for the preference file name.

Following is the code to get preferences:

   SharedPreferences preferences = getPreferences(MODE_PRIVATE);
   int storedPreference = preferences.getInt("storedInt", 0);

The code to store values is also same as in case of shared preferences.

   SharedPreferences preferences = getPreference(MODE_PRIVATE);
   SharedPreferences.Editor editor = preferences.edit();
   editor.putInt("storedInt", storedPreference); // value to store
   editor.commit();

You can also use other methods like storing the activity state in database. Note Android also contains a package called android.preference. The package defines classes to implement application preferences UI.

To see some more examples check Android's Data Storage post on developers site.

For more info, check this link:

Making data persistent in android

Upvotes: 0

Anu
Anu

Reputation: 1914

The easiest way of retrieving log in information from other activities is using "SharedPreferences". I strongly recommend this method for storage and retrieval of Username and Password. Because you can access this information from anywhere in the application without any complications. The log in information may have to use repeatedly in an application.

Upvotes: 1

binW
binW

Reputation: 13672

For your purpose both, SQLite Database and SharedPreferences will work. But I would suggest SharedPreferences as they are very easy to use. Some ppl like to create a class to hold variables like this but the benefit of SQLite and SharedPreferences file is that the user login name and password information will be with you even if the app goes in background and gets destroyed. So when the user comes back to your app, you can sign them in again without asking for password. If user explicitly decides to logout, you can simply remove the login information from shared preferences file

Upvotes: 3

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