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

Question

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 s

Answer 1

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(...)

Answer 2

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 :)

Answer 3

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.

Answer 4

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();
}
}

Answer 5

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();
    }

Answer 6

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);