A wrapper over shared preferences. *Dependency required: A custom application class which provides global app context. (https://gist.github.com/KalpeshTalkar/c4c7ccf8003c6214c11226b86c565bb7)

LocalStorage.java

//
// Copyright © 2017 Kalpesh Talkar. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// For support: https://gist.github.com/KalpeshTalkar/eebb69a3fee4fc8ffcf4eac25757b435
//

import android.content.Context;
import android.content.SharedPreferences;
import android.util.Log;

/**
 * Created by Kalpesh on 17/08/17.
 */

/// A wrapper/abstraction layer over SharedPreferences which features storage/retrieving data from/to SharedPreferences
public class LocalStorage {

    public static String AUTH_TOKEN_KEY = "X-AUTH-TOKEN";

    /// Shared preferences name
    private static String APP_PREFS = "AppPrefs";

    private static String KEY_COUPON_CODE = "couponCode";
    private static String KEY_COUPON_AMT = "couponAmt";

    /// Get instance of shared preferences in private mode
    private static SharedPreferences getSharedPrefs() {
        return App.sharedContext().getSharedPreferences(APP_PREFS, Context.MODE_PRIVATE);
    }

    /// Get instance of Editor
    private static SharedPreferences.Editor getEditor() {
        return getSharedPrefs().edit();
    }

    /// Get locally stored value for specific key in the desired data type
    /// The value can be null if it does not exist or cannot be casted to the desired data type
    public static <T extends Object> T getValue(String key, Object defaultValue, Class<T> type) {
        Object value = null;
        SharedPreferences sharedPrefs = getSharedPrefs();
        if (type.equals(String.class)) {    // String
            String defVal = "";
            if (defaultValue != null && defaultValue instanceof String) {
                defVal = (String) defaultValue;
            }
            try {
                value = sharedPrefs.getString(key, defVal);
            } catch (Exception e) {
                Log.e("LocalStorage", "Error getting value for key: " + key + "\nError: " + e.getMessage());
            }

        } else if (type.equals(Integer.class)) {    // Integer
            int defVal = 0;
            if (defaultValue != null && defaultValue instanceof Integer) {
                defVal = (int) defaultValue;
            }
            try {
                value = sharedPrefs.getInt(key, defVal);
            } catch (Exception e) {
                Log.e("LocalStorage", "Error getting value for key: " + key + "\nError: " + e.getMessage());
            }

        } else if (type.equals(Float.class)) {  // Float
            float defVal = 0;
            if (defaultValue != null && defaultValue instanceof Float) {
                defVal = (float) defaultValue;
            }
            try {
                value = sharedPrefs.getFloat(key, defVal);
            } catch (Exception e) {
                Log.e("LocalStorage", "Error getting value for key: " + key + "\nError: " + e.getMessage());
            }

        } else if (type.equals(Boolean.class)) {    // Boolean
            boolean defVal = false;
            if (defaultValue != null && defaultValue instanceof Boolean) {
                defVal = (boolean) defaultValue;
            }
            try {
                value = sharedPrefs.getBoolean(key, defVal);
            } catch (Exception e) {
                Log.e("LocalStorage", "Error getting value for key: " + key + "\nError: " + e.getMessage());
            }

        } else if (type.equals(Long.class)) {   // Long
            long defVal = 0;
            if (defaultValue != null && defaultValue instanceof Long) {
                defVal = (long) defaultValue;
            }
            try {
                value = sharedPrefs.getLong(key, defVal);
            } catch (Exception e) {
                Log.e("LocalStorage", "Error getting value for key: " + key + "\nError: " + e.getMessage());
            }
        } else if (type.equals(Float.class)) {   // Float
            float defVal = 0;
            if (defaultValue != null && defaultValue instanceof Float) {
                defVal = (float) defaultValue;
            }
            try {
                value = sharedPrefs.getFloat(key, defVal);
            } catch (Exception e) {
                Log.e("LocalStorage", "Error getting value for key: " + key + "\nError: " + e.getMessage());
            }
        }
        return type.cast(value);
    }

    /// Store data locally for specific key
    public static void putValue(Object value, String key) {
        SharedPreferences.Editor editor = getEditor();
        if (value instanceof String) {    // String
            editor.putString(key, (String) value);

        } else if (value instanceof Integer) {    // Integer
            editor.putInt(key, (int) value);

        } else if (value instanceof Float) {  // Float
            editor.putFloat(key, (float) value);

        } else if (value instanceof Boolean) {    // Boolean
            editor.putBoolean(key, (boolean) value);

        } else if (value instanceof Long) {   // Long
            editor.putLong(key, (long) value);

        } else if (value instanceof Float) {   // Float
            editor.putFloat(key, (float) value);
        }
        editor.commit();
    }

    public static void saveToken(String token) {
        if (token == null) {
            token = "";
        }
        putValue(token, AUTH_TOKEN_KEY);
    }

    public static String getToken() {
        return getValue(AUTH_TOKEN_KEY, "", String.class);
    }

}

Usage:
Storing a value:
LocalStorage.putValue(true, "isLoggedIn");

Fetching value:
boolean isLoggedIn = LocalStorage.getValue("isLoggedIn", false, Boolean.class);