RFID Enabled Fish Tracking

Managing In-App Storage

Link to Github

Android Reference

There are two major storage options that we have explored:

• Shared Preferences

• External Storage

Shared Preferences

Shared preferences are mostly used for storing key-value pairs.

1. Declaring the variables:

   private static SharedPreferences prefStorage;
   private static SharedPreferences.Editor editor;
   

2. Defining the variables:

   prefStorage = context.getSharedPreferences(YOUR_IDENTIFIER, Context.MODE_PRIVATE);
   editor = prefStorage.edit();
   

3. Writing to Shared Preferences:

   private static void writeToPref(String Key, String message) {
       editor.putString(Key, message);
       editor.commit();
   }
   

4. Reading from Shared Preferences:

   private static String readFromPref(String name) {
       return prefStorage.getString(name, null);
   }
   

5. Deleting in Shared Preferences:

   private static Boolean deletePref(String Key) {
       editor.remove(Key);
       return editor.commit();
   }
   

External Storage

App-Private Storage

Using App-Private Storage does not require runtime permissions.

Application data are all stored under the directory you can obtain by context.getFilesDir().

However, when the application gets uninstalled, everything under the folder will be removed.

Your Data is NOT accessible by users.

App-Public Storage

Using App-Private storage does not require runtime permissions.

Application data are all stored under the directory you can obtain by context.getExternalFilesDir().

However, when the application gets uninstalled, everything under the folder will be removed.

Global Storage

Using Global Storage requires runtime permissions.

Application data are all stored under the directory you can obtain by context.getExternalFilesStorage().

Data under this directory is both visible to users and persists after the app is uninstalled.

Usage

In this example, we’re using app-public storage.

To use other options, simply swap out the getExternalFilesDir() with corresponding alternatives.

1. Declaration:

   private static File fileStorage = null;//Main Directory File
   

2. Definition:

   fileStorage = new File(context.getExternalFilesDir(null), YOUR_IDENTIFIER);
   if (!fileStorage.exists()) {
       fileStorage.mkdirs();
   }
   

3. Writing:

   private static void writeToFile(String FileName, String messageBody) {
       try {
           File savedFile = new File(fileStorage.getAbsolutePath() + "/" + FileName);
      
           FileWriter fWriter;
      
           if (!savedFile.exists()) {
               Boolean res = savedFile.getParentFile().mkdirs(); /*makes parent directories*/
               savedFile.createNewFile();
           }
      
           fWriter = new FileWriter(savedFile);
      
           fWriter.write(messageBody);/*write data*/
           fWriter.flush();/*flush writer*/
           fWriter.close();/*close writer*/
      
       } catch (Exception e) {
           e.printStackTrace();
       }
   }
   

4. Reading:

   private static String readFromFile(String FileName) {
           /*First check if main directory is present or not*/
           if (!fileStorage.exists()) {
               return null;
           } else {
               /*Then check if text file is present or not*/
               File savedFile = new File(fileStorage.getAbsolutePath() + "/" + FileName);
               if (!savedFile.exists())
                   return null;
               else {
                   /*Finally read data using FileReader*/
                   try {
                       FileReader rdr = new FileReader(fileStorage.getAbsolutePath() + "/" + FileName);
      
                       char[] inputBuffer = new char[READ_BLOCK_SIZE];/*get Block size as buffer*/
                       String savedData = "";
                       int charRead = rdr.read(inputBuffer);
                       /*Read all data one by one by using loop and add it to string created above*/
                       for (int k = 0; k < charRead; k++) {
                           savedData += inputBuffer[k];
                       }
                       return savedData;/*return saved data*/
      
                   } catch (Exception e) {
                       e.printStackTrace();
                       Log.e("Message", e.getLocalizedMessage());
                       return null;
                   }
               }
           }
      
       }
   

5. Deleting:

   private static Boolean deleteFile(String FileName) {
      
       /*Check if main directory is present or not*/
       if (!fileStorage.exists())
           return false;
       else {
           /*Now Check if text file is present or not*/
           File savedFile = new File(fileStorage.getAbsolutePath() + "/" + FileName);
           if (!savedFile.exists())
               return false;
           else {
               savedFile.delete();/*If text file is present then delete file*/
               return true;
           }
      
       }
   }