CODEWITHSUNDEEP
androidsharedpreferences
Jake Wilson
Jake Wilson

Reputation: 91193

Android - How to use SharedPreferences in non-Activity class?

How do you use SharedPreferences in a non-Activity class? I tried making a generic Preferences utility class and importing android.content.Context but Eclipse still wouldn't let me use getSharedPreferences().

Upvotes: 51

Views: 62708

Answers (12)

Santi
Santi

Reputation: 1802

The solution i found to this was:

1-In an MainActivity class (i.e always launched before getting any context in project) create a static variable for the context:

public static Context contextOfApplication;

2-In an important method of this class (Such as onCreate, the constructor, etc) initialize this variable using the getApplicationContext method:

public void onCreate() {
    contextOfApplication = getApplicationContext();
}

3-In the same class Create a "getter" method for this variable (it must also be static):

public static Context getContextOfApplication(){
    return contextOfApplication;
}

4-In the non-activity class get the context by calling the created method statically:

Context applicationContext = MyActivityClass.getContextOfApplication();

5-Use the PreferenceManager Class to get the SharedPreferences variable:

SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(applicationContext);

Hope it helps.

Upvotes: 51

Bartosz Kolej
Bartosz Kolej

Reputation: 117

In main activity add: u will get global static shared preferences object

 companion object {    
    lateinit var sharedPreferences: SharedPreferences
}

override fun onCreate(savedInstanceState: Bundle?) {
 sharedPreferences = applicationContext.getSharedPreferences(
        SHARED_PREFERENCE_NAME,
        Context.MODE_PRIVATE
    )

Upvotes: 2

Cihat Gündüz
Cihat Gündüz

Reputation: 21468

In Kotlin, there's a nice & simple wrapper-based solution – just copy & paste the code into a new AppPreferences.kt file and follow the 4 TODO steps outlined in the code:

import android.content.Context
import android.content.Context.MODE_PRIVATE
import android.content.SharedPreferences
import androidx.core.content.edit

object AppPreferences {
    private var sharedPreferences: SharedPreferences? = null

    // TODO step 1: call `AppPreferences.setup(applicationContext)` in your MainActivity's `onCreate` method
    fun setup(context: Context) {
        // TODO step 2: set your app name here
        sharedPreferences = context.getSharedPreferences("<YOUR_APP_NAME>.sharedprefs", MODE_PRIVATE)
    }

    // TODO step 4: replace these example attributes with your stored values
    var heightInCentimeters: Int?
        get() = Key.HEIGHT.getInt()
        set(value) = Key.HEIGHT.setInt(value)

    var birthdayInMilliseconds: Long?
        get() = Key.BIRTHDAY.getLong()
        set(value) = Key.BIRTHDAY.setLong(value)

    private enum class Key {
        HEIGHT, BIRTHDAY; // TODO step 3: replace these cases with your stored values keys

        fun getBoolean(): Boolean? = if (sharedPreferences!!.contains(name)) sharedPreferences!!.getBoolean(name, false) else null
        fun getFloat(): Float? = if (sharedPreferences!!.contains(name)) sharedPreferences!!.getFloat(name, 0f) else null
        fun getInt(): Int? = if (sharedPreferences!!.contains(name)) sharedPreferences!!.getInt(name, 0) else null
        fun getLong(): Long? = if (sharedPreferences!!.contains(name)) sharedPreferences!!.getLong(name, 0) else null
        fun getString(): String? = if (sharedPreferences!!.contains(name)) sharedPreferences!!.getString(name, "") else null

        fun setBoolean(value: Boolean?) = value?.let { sharedPreferences!!.edit { putBoolean(name, value) } } ?: remove()
        fun setFloat(value: Float?) = value?.let { sharedPreferences!!.edit { putFloat(name, value) } } ?: remove()
        fun setInt(value: Int?) = value?.let { sharedPreferences!!.edit { putInt(name, value) } } ?: remove()
        fun setLong(value: Long?) = value?.let { sharedPreferences!!.edit { putLong(name, value) } } ?: remove()
        fun setString(value: String?) = value?.let { sharedPreferences!!.edit { putString(name, value) } } ?: remove()

        fun remove() = sharedPreferences!!.edit { remove(name) }
    }
}

Now from anywhere within your app you can get a value like this:

val heightInCentimeters: Int? = AppPreferences.heightInCentimeters
val heightOrDefault: Int = AppPreferences.heightInCentimeters ?: 170

Setting a value to the SharedPreferences is just as easy:

AppPreferences.heightInCentimeters = 160 // sets a new value

Upvotes: 4

Thodoris
Thodoris

Reputation: 65

For Kotlin and for default preference file, you can use the following code:

val sharedPref = activity?.getPreferences(Context.MODE_PRIVATE)

Upvotes: -1

Zohab Ali
Zohab Ali

Reputation: 9544

In Kotlin you can do this:

val myClass = MyClass(this)

Now this is how you can get context in class

class MyClass(context: Context) {

    val context: Context = context

}

Now to get Shared Preferences with context you can do this:

context.getSharedPreferences(...)

Upvotes: 1

Mustafa Tameemi
Mustafa Tameemi

Reputation: 1176

Use this code to get the context from activity.

if (context != null) {
    SharedPreferences sharedPrefs = context.getSharedPreferences("YOUR.PACKAGE.NAME", MODE_PRIVATE);
}

Upvotes: 0

Code Spy
Code Spy

Reputation: 9954

Using a static method to use SharedPreference without Context Object explained here

In MainActivity before OnCreate

public static SharedPreferences preferences;

In OnCreate method add

preferences = getSharedPreferences( getPackageName() + "_preferences", MODE_PRIVATE);

Create a PreferenceHelper Class with static methods of Getters and Setters

public class PreferenceHelper {

final public static String KEY_DEMO_NAME = "Demo Name";
public static void setName(String value) {
    MainActivity.preferences.edit().putString(KEY_DEMO_NAME, value ).commit();
}
public static String getName() {
    return MainActivity.preferences.getString(KEY_DEMO_NAME,"");
}

}

Upvotes: 2

Mohsinali
Mohsinali

Reputation: 553

create SharedPreferences class

 /**
     * @param mContext
     * @param key
     * @param value
     */
    public static void savePreferences(Context mContext, String key, String value) {
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(mContext);
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putString(key, value).apply();
    }

    /**
     * @param context
     * @param keyValue
     * @return
     */
    public static String getPreferences(Context context, String keyValue) {
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
        return sharedPreferences.getString(keyValue, "");
    }

    /**
     * @param mContext
     */
    public static void removeAllSharedPreferences(Context mContext) {
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(mContext);
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.clear().apply();
    }

Upvotes: 0

Atiar Talukdar
Atiar Talukdar

Reputation: 746

use this code to a new class. 

import android.content.Context;
import android.content.SharedPreferences;

/**
   * Created by Atiar Talukdar on 6/5/2017.
*/

public class TemporaryStorageSharedPreference {
protected final static int DEFAULT = 0;
int temp = 0;

public int readSharedPreference(Context context, String spName,String key){
    SharedPreferences sharedPreferences = context.getSharedPreferences(spName, Context.MODE_PRIVATE);
    return temp = sharedPreferences.getInt(key,DEFAULT);
}

public void writeSharedPreference(Context context,String ammount,String spName,String key ){

    SharedPreferences sharedPreferences = context.getSharedPreferences(spName, Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putInt(key, DEFAULT);
    editor.commit();
}
}

Upvotes: 1

Sandor
Sandor

Reputation: 1849

SharedPreferences are related to context. You can only reference it through a context.

You can simply pass context as a parameter to your class. For example in the constructor.

In your activity do:

MyClass myClass = new MyClass(this);

Upvotes: 52

joninx
joninx

Reputation: 1780

First, declare a private attribute in your class. In my case, I have a BaseAdapter class:

private final Context ctx;
private final Vector<Acto> actos;

public ActoAdaptador(Context ctx, Vector<Acto> as) {
    super();
    this.ctx = ctx;
    this.actos = as;
}

Then, when to use the SharedPreferences:

ctx.getSharedPreferences("com.joninazio.euskofest.UsingPreferences_preferences", Context.MODE_PRIVATE)

That way works for me at least :)

Upvotes: 0

Dan S
Dan S

Reputation: 9189

Try using default preferences with an Application context. A context is similar to the environment an application runs in on linux or windows (e.g. environment variables like PATH windowing style or console size). Each Activity and Service has its own Context too for example screen orientation, theme, and label, etc. but for your application you don't want the context of the Activity, you want something global to the app, this is where context.getApplicationContext() is useful. This the same throughout the app and will always give you the same default preferences.

Upvotes: 2

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