Shared Preferences in Android

Shared Preferences in Android 

In Android Programming, we use Shared Preferences to save temporary values to use in our Android App.

Value saved in shared preferences available for all activities of our app and availaible until we uninstall the app or clear data or manually delete the values.

Values like coins given to users after some task, or name or email of a user to show at some points in our app.

• Create Shared Preferences in Android App.
• Put values in Preferences
• Create a Set<String> to add list of values.
• Get values from Shared Preferences.
• Show it on  a Text View.
• Use Debugger to see the values in Shared Preferences.

XML activity to create some Text Views to show values

XML activity

 <?xml version="1.0" encoding="utf-8"?>  
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
   xmlns:app="http://schemas.android.com/apk/res-auto"  
   xmlns:tools="http://schemas.android.com/tools"  
   android:layout_width="match_parent"  
   android:layout_height="match_parent"  
   android:orientation="vertical"  
   tools:context=".SharedPrefs">  
   <TextView  
     android:layout_width="wrap_content"  
     android:layout_height="wrap_content"  
     android:id="@+id/name"  
     android:padding="5dp"/>  
   <TextView  
     android:layout_width="wrap_content"  
     android:layout_height="wrap_content"  
     android:id="@+id/email"  
     android:padding="5dp"/>  
   <TextView  
     android:layout_width="wrap_content"  
     android:layout_height="wrap_content"  
     android:id="@+id/subscribe"  
     android:padding="5dp"/>  
   <TextView  
     android:layout_width="wrap_content"  
     android:layout_height="wrap_content"  
     android:id="@+id/percentage"  
     android:padding="5dp"/>  
   <TextView  
     android:layout_width="wrap_content"  
     android:layout_height="wrap_content"  
     android:id="@+id/value"  
     android:padding="5dp"/>  
   <TextView  
     android:layout_width="wrap_content"  
     android:layout_height="wrap_content"  
     android:id="@+id/string_set"  
     android:padding="5dp"/>  
 </LinearLayout>  

Then in Java file we will create Shared Preferences and save and get data from their.

Java Activity

 package studio.harpreet.sampleproject;  
 import android.content.SharedPreferences;  
 import android.os.Bundle;  
 import android.util.Log;  
 import android.widget.TextView;  
 import androidx.appcompat.app.AppCompatActivity;  
 import java.util.HashSet;  
 import java.util.Iterator;  
 import java.util.Set;  
 public class SharedPrefs extends AppCompatActivity {  
   SharedPreferences preferences;  
   SharedPreferences.Editor editor;  
   String name;  
   String email;  
   Boolean subs;  
   int value;  
   float percentage;  
   Set<String> getDataset = new HashSet<>();  
   Set<String> dataset = new HashSet<>(); // almost same as arraylist  
   TextView name_tv,email_tv,sub_tv,perc_tv,int_tv,string_set;  
   @Override  
   protected void onCreate(Bundle savedInstanceState) {  
     super.onCreate(savedInstanceState);  
     setContentView(R.layout.activity_shared_prefs);  
     name_tv = findViewById(R.id.name);  
     email_tv = findViewById(R.id.email);  
     sub_tv = findViewById(R.id.subscribe);  
     perc_tv = findViewById(R.id.percentage);  
     string_set = findViewById(R.id.string_set);  
     int_tv = findViewById(R.id.value);  
     dataset.add("123");  
     dataset.add("456");  
     dataset.add("789");  
     //some values in shared preferences are from another activity, so don't be confuse about that  
     preferences = getSharedPreferences(getPackageName(),MODE_PRIVATE); // 1.) you can create many preferences with different id  
     editor = preferences.edit();  
   //adding values to preferences  
     editor.putString("name","Harpreet");  
     editor.putString("email","contact@harpreetstudio.com");  
     editor.putBoolean("subscribe",true);  
     editor.putFloat("percentage", (float) 99.9);  
     editor.putInt("value",1);  
     editor.putStringSet("stringset",dataset);  
     // after adding all values in editor, you should call editor.commit to add values in preferences  
     editor.apply();  
     editor.commit();  
   //get values from preferences  
     if(preferences != null) //if shared preferences exists  
     {  
       if(preferences.getString("name","") != null) // if string value exists  
       {  
         name = preferences.getString("name",""); //second string is only a default value we get  
       }  
       if(preferences.getString("email","") != null) // if string value exists  
       {  
         email = preferences.getString("email",""); //second string is only a default value we get  
       }  
       if(preferences.contains("subscribe")) // if preferences contains boolean value  
       {  
         subs = preferences.getBoolean("subscribe",false); //second string is only a default value we get  
       }  
       if(preferences.contains("value")) // if int value exists  
       {  
         value = preferences.getInt("value",0); //second string is only a default value we get  
       }  
       if(preferences.contains("percentage")) // if string value exists  
       {  
         percentage = preferences.getFloat("percentage",0); //second string is only a default value we get  
       }  
       if(preferences.contains("stringset")) // if string value exists  
       {  
         getDataset = preferences.getStringSet("stringset",null); //second string is only a default value we get  
       }  
       name_tv.setText(name);  
       sub_tv.setText(String.valueOf(subs));  
       email_tv.setText(String.valueOf(email));  
       int_tv.setText(String.valueOf(value));  
       perc_tv.setText(String.valueOf(percentage));  
       string_set.setText(String.valueOf(getDataset));  
       //you will get default values if value is null in shared preferences..  
       //to get values(elements) from string set  
       Iterator<String> it = getDataset.iterator();  
       int count = 0;  
       while (it.hasNext())  
       {  
         String value = it.next();  
         Log.e("TAG", "onCreate:count: "+count+" , "+value );  
         count++;  
       }  
       // now we will use debugger to see the values in shared preferences..  
     }  
   }  
 }  

For manually removing the value you can use 

editor.clear  // to clear all values from preferences

or

editor.remove("name"); // to remove a specific value from preferences

//don't forget to use these commands after changes in editor.

editor.apply

editor.commit

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