Storing data in SharedPreferences

In previous post Store Data – SharedPreferences – Android we discussed about cases, when we should save data in SharedPreferences. Here is a demo Android App for the same.

Create a new Android project using following information.

Project Name

SharedPreference Demo

Package Name

com.pcsalt.example.sharedpreferencedemo

Minimum SDK Version

Activity Type

Empty Activity

Activity Name

MainActivity

Layout Name

activity_name

Adding dependencies in build.gradle

In this tutorial we are going to display all saved keys and values in RecyclerView. So, following dependency needs to be added into SharedPreferenceDemo/app/build.gradle.

dependencies { compile ‘com.android.support:appcompat-v7:23.0.1’ compile ‘com.android.support:recyclerview-v7:23.0.1’ }

Update layout of activity_main.xml

By default, activity_main.xml comes with RelativeLayout as parent Layout and a TextView with Hello world text. Update this layout to have:
– two EditText for Key and Value,
– one Button to save Key and Value pair in SharedPreferences, and
– a RecyclerView to display all saved values in SharedPreferences.

Create list item for RecyclerView

The RecyclerView would display the saved key, value pair in a list. So, create a resource file list_item_pref.xml

Create Utility classes

It is a good idea to keep things separate, if it does not do the similar thing. For this purpose, we have two utility classes.
– Utility.java : for getting text from EditText.
– PrefUtil.java : for performing basic operations on SharedPreferences.

Create Utility.java

package com.pcsalt.example.sharedpreferencedemo; import android.widget.TextView; /** * Created by krrishnaaaa on Oct 02, 2015 */ public final class Utility { public static String getText(TextView textView) { String text = ""; if (textView != null) { text = textView.getText().toString(); } return text; } }

Create PrefUtil.java

package com.pcsalt.example.sharedpreferencedemo; import android.content.Context; import android.content.SharedPreferences; import android.preference.PreferenceManager; import java.util.ArrayList; import java.util.List; import java.util.Map; /** * Created by krrishnaaaa on Oct 02, 2015 */ public final class PrefUtil { private static SharedPreferences getPref(Context context) { return PreferenceManager.getDefaultSharedPreferences(context); } public static void saveString(Context context, String key, String value) { getPref(context).edit().putString(key, value).apply(); } public static String getString(Context context, String key, String defValue) { return getPref(context).getString(key, defValue); } public static void removeString(Context context, String key) { getPref(context).edit().remove(key).apply(); } public static List getAllValues(Context context) { Map values = getPref(context).getAll(); List prefDataList = new ArrayList(); for (Map.Entry entry : values.entrySet()) { PrefData prefData = new PrefData(); prefData.key = entry.getKey(); prefData.value = entry.getValue().toString(); prefDataList.add(prefData); } return prefDataList; } }

Create model class PrefData.java

This model class would hold the key and value stored in SharedPreferences and list of this model would be displayed in RecyclerView.

package com.pcsalt.example.sharedpreferencedemo; /** * Created by krrishnaaaa on Oct 02, 2015 */ public final class PrefData { public String key; public String value; public PrefData() { } public PrefData(String key, String value) { this.key = key; this.value = value; } @Override public boolean equals(Object object) { return object instanceof PrefData && key.equals(((PrefData) object).key); } @Override public int hashCode() { return super.hashCode(); } }

Create Adapter for RecyclerView

This adapter will hold and display the key value stored in SharedPreferences.

package com.pcsalt.example.sharedpreferencedemo; import android.content.Context; import android.support.v7.widget.RecyclerView; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.TextView; import java.util.List; /** * Created by krrishnaaaa on Oct 02, 2015 */ public class PrefAdapter extends RecyclerView.Adapter { private LayoutInflater mLayoutInflater; private List mPrefDataList; public PrefAdapter(Context context, List prefDataList) { this.mLayoutInflater = LayoutInflater.from(context); this.mPrefDataList = prefDataList; } @Override public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { View view = mLayoutInflater.inflate(R.layout.list_item_pref, parent, false); return new ViewHolder(view); } @Override public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) { if (holder instanceof ViewHolder) { ViewHolder viewHolder = (ViewHolder) holder; PrefData current = mPrefDataList.get(position); viewHolder.textViewKey.setText(current.key); viewHolder.textViewValue.setText(current.value); } } @Override public int getItemCount() { if (mPrefDataList != null) { return mPrefDataList.size(); } else { return 0; } } static class ViewHolder extends RecyclerView.ViewHolder { TextView textViewKey, textViewValue; public ViewHolder(View itemView) { super(itemView); textViewKey = (TextView) itemView.findViewById(R.id.text_view_key); textViewValue = (TextView) itemView.findViewById(R.id.text_view_value); } } }

Update MainActivity.java to store and display contents to/from SharedPreferences

MainActivity will be performing following tasks:
– Link all views from its layout
– Save key and value from EditText in SharedPreferences
– Update RecyclerView with the values stored in SharedPreferences

package com.pcsalt.example.sharedpreferencedemo; import android.content.Context; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.view.View; import android.widget.Button; import android.widget.EditText; import com.pcsalt.example.sharedpreferencedemo.listener.RecyclerClickListener; import com.pcsalt.example.sharedpreferencedemo.listener.RecyclerTouchListener; import java.util.List; public class MainActivity extends AppCompatActivity { private Context mContext = MainActivity.this; private EditText mEditTextKey; private EditText mEditTextValue; private List mPrefDataList; private PrefAdapter mPrefAdapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initViews(); } private void initViews() { mEditTextKey = (EditText) findViewById(R.id.edit_text_key); mEditTextValue = (EditText) findViewById(R.id.edit_text_value); Button buttonSave = (Button) findViewById(R.id.button_save); buttonSave.setOnClickListener(mOnClickListener); RecyclerView recyclerViewPrefValues = (RecyclerView) findViewById(R.id.recycler_view_pref_values); recyclerViewPrefValues.setLayoutManager(new LinearLayoutManager(mContext)); mPrefDataList = PrefUtil.getAllValues(mContext); mPrefAdapter = new PrefAdapter(mContext, mPrefDataList); recyclerViewPrefValues.setAdapter(mPrefAdapter); RecyclerTouchListener recyclerTouchListener = new RecyclerTouchListener(mContext, recyclerViewPrefValues, new RecyclerClickListener() { @Override public void onClick(View view, int position) { PrefData prefData = mPrefDataList.get(position); PrefUtil.removeString(mContext, prefData.key); mPrefDataList.remove(position); mPrefAdapter.notifyItemRemoved(position); } }); recyclerViewPrefValues.addOnItemTouchListener(recyclerTouchListener); } private void saveValueInPref() { String key = Utility.getText(mEditTextKey); String value = Utility.getText(mEditTextValue); if (key.isEmpty()) { mEditTextKey.setError(“Enter key”); } else if (value.isEmpty()) { mEditTextValue.setError(“Enter value”); } else { PrefUtil.saveString(mContext, key, value); mEditTextKey.setText(""); mEditTextValue.setText(""); PrefData newPrefData = new PrefData(key, value); if (mPrefDataList.contains(newPrefData)) { int index = mPrefDataList.indexOf(newPrefData); mPrefDataList.remove(index); mPrefAdapter.notifyItemRemoved(index); } mPrefDataList.add(newPrefData); int position = mPrefAdapter.getItemCount() - 1; mPrefAdapter.notifyItemInserted(position); } } private View.OnClickListener mOnClickListener = new View.OnClickListener() { @Override public void onClick(View v) { switch (v.getId()) { case R.id.button_save: saveValueInPref(); break; } } }; }

Download source code

Working source code is shared on GitHub – SharedPreference-Demo