Read Write String from to a File in Android

Question

I want to save a file to the internal storage by getting the text inputted from EditText  Then I want the same file to return the inputted text in String form and save it to another String which is to be used later   Here s the code   package com omm easybalancerecharge    import android app Activity  import android content Context  import android content Intent  import android net Uri  import android os Bundle  import android telephony TelephonyManager  import android view Menu  import android view View  import android view View OnClickListener  import android widget Button  import android widget EditText  import android widget TextView   public class MainActivity extends Activity         Override     protected void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout activity main            final EditText num    EditText  findViewById R id sNum           Button ch    Button  findViewById R id rButton           TelephonyManager operator    TelephonyManager  getSystemService Context TELEPHONY SERVICE           String opname   operator getNetworkOperatorName            TextView status    TextView  findViewById R id setStatus           final EditText ID    EditText  findViewById R id IQID           Button save    Button  findViewById R id sButton            final String myID         When Reading The File Back  I Need To Store It In This String For Later Use          save setOnClickListener new OnClickListener                   Override             public void onClick View v                       TODO Auto-generated method stub                    Get Text From EditText  ID  And Save It To Internal Memory                                   if  opname contentEquals  zain SA                  status setText  Your Network Is      opname             else               status setText  No Network                      ch setOnClickListener new OnClickListener                   Override             public void onClick View v                       TODO Auto-generated method stub                    Read From The Saved File Here And Append It To String  myID                    String hash   Uri encode                       Intent intent   new Intent Intent ACTION CALL                   intent setData Uri parse  tel  141       Use The String With Data Retrieved Here   num getText                             hash                    startActivity intent                                     I have included comments to help you further analyze my points as to where I want the operations to be done variables to be used

User · Answer

the first thing we need is the permissions in AndroidManifest.xml

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_INTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_INTERNAL_STORAGE" />

so in an asyncTask Kotlin class, we treat the creation of the file

    import android.os.AsyncTask
    import android.os.Environment
    import android.util.Log
    import java.io.*
    class WriteFile: AsyncTask<String, Int, String>() {
        private val mFolder = "/MainFolder"
        lateinit var folder: File
        internal var writeThis = "string to cacheApp.txt"
        internal var cacheApptxt = "cacheApp.txt"
        override fun doInBackground(vararg writethis: String): String? {
            val received = writethis[0]
            if(received.isNotEmpty()){
                writeThis = received
            }
            folder = File(Environment.getExternalStorageDirectory(),"$mFolder/")
            if(!folder.exists()){
                folder.mkdir()
                val readME = File(folder, cacheApptxt)
                val file = File(readME.path)
                val out: BufferedWriter
                try {
                    out = BufferedWriter(FileWriter(file, true), 1024)
                    out.write(writeThis)
                    out.newLine()
                    out.close()
                    Log.d("Output_Success", folder.path)
                } catch (e: Exception) {
                    Log.d("Output_Exception", "$e")
                }
            }
            return folder.path

    }

        override fun onPostExecute(result: String) {
            super.onPostExecute(result)

            if(result.isNotEmpty()){
                //implement an interface or do something
                Log.d("onPostExecuteSuccess", result)
            }else{
                Log.d("onPostExecuteFailure", result)
            }
        }

    }

Of course if you are using Android above Api 23, you must handle the request to allow writing to device memory. Something like this

    import android.Manifest
    import android.content.Context
    import android.content.pm.PackageManager
    import android.os.Build
    import androidx.appcompat.app.AppCompatActivity
    import androidx.core.app.ActivityCompat
    import androidx.core.content.ContextCompat

    class ReadandWrite {
        private val mREAD = 9
        private val mWRITE = 10
        private var readAndWrite: Boolean = false
        fun readAndwriteStorage(ctx: Context, atividade: AppCompatActivity): Boolean {
            if (Build.VERSION.SDK_INT < 23) {
                readAndWrite = true
            } else {
                val mRead = ContextCompat.checkSelfPermission(ctx, Manifest.permission.READ_EXTERNAL_STORAGE)
                val mWrite = ContextCompat.checkSelfPermission(ctx, Manifest.permission.WRITE_EXTERNAL_STORAGE)

                if (mRead != PackageManager.PERMISSION_GRANTED) {
                    ActivityCompat.requestPermissions(atividade, arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE), mREAD)
                } else {
                    readAndWrite = true
                }

                if (mWrite != PackageManager.PERMISSION_GRANTED) {
                    ActivityCompat.requestPermissions(atividade, arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE), mWRITE)
                } else {
                    readAndWrite = true
                }
            }
            return readAndWrite
        }
    }

then in an activity, execute the call.

  var pathToFileCreated = ""
    val anRW = ReadandWrite().readAndwriteStorage(this,this)
    if(anRW){
        pathToFileCreated =  WriteFile().execute("onTaskComplete").get()
        Log.d("pathToFileCreated",pathToFileCreated)
    }

User · Answer

For those looking for a general strategy for reading and writing a string to file   First  get a file object  You ll need the storage path  For the internal storage  use   File path   context getFilesDir      For the external storage  SD card   use   File path   context getExternalFilesDir null     Then create your file object   File file   new File path   my-file-name txt      Write a string to the file  FileOutputStream stream   new FileOutputStream file   try       stream write  text-to-write  getBytes       finally       stream close        Or with Google Guava     String contents   Files toString file  StandardCharsets UTF 8     Read the file to a string  int length    int  file length     byte   bytes   new byte length    FileInputStream in   new FileInputStream file   try       in read bytes     finally       in close       String contents   new String bytes        Or if you are using Google Guava  String contents   Files toString file  UTF-8      For completeness I ll mention   String contents   new Scanner file  useDelimiter    A   next      which requires no libraries  but benchmarks 50  - 400  slower than the other options  in various tests on my Nexus 5    Notes  For each of these strategies  you ll be asked to catch an IOException     The default character encoding on Android is UTF-8     If you are using external storage  you ll need to add to your manifest either    lt uses-permission android name  android permission READ EXTERNAL STORAGE   gt    or   lt uses-permission android name  android permission WRITE EXTERNAL STORAGE   gt    Write permission implies read permission  so you don t need both

User · Answer

Hope this might be useful to you   Write File   private void writeToFile String data Context context        try           OutputStreamWriter outputStreamWriter   new OutputStreamWriter context openFileOutput  config txt   Context MODE PRIVATE            outputStreamWriter write data           outputStreamWriter close              catch  IOException e            Log e  Exception    File write failed      e toString                Read File   private String readFromFile Context context         String ret            try           InputStream inputStream   context openFileInput  config txt             if   inputStream    null                 InputStreamReader inputStreamReader   new InputStreamReader inputStream               BufferedReader bufferedReader   new BufferedReader inputStreamReader               String receiveString                   StringBuilder stringBuilder   new StringBuilder                 while    receiveString   bufferedReader readLine       null                     stringBuilder append   n   append receiveString                              inputStream close                ret   stringBuilder toString                        catch  FileNotFoundException e            Log e  login activity    File not found      e toString           catch  IOException e            Log e  login activity    Can not read file      e toString                return ret

User · Answer

check the below code   Reading from a file in the filesystem   FileInputStream fis   null      try            fis   context openFileInput fileName           InputStreamReader isr   new InputStreamReader fis              READ STRING OF UNKNOWN LENGTH         StringBuilder sb   new StringBuilder            char   inputBuffer   new char 2048           int l             FILL BUFFER WITH DATA         while   l   isr read inputBuffer      -1                sb append inputBuffer  0  l                        CONVERT BYTES TO STRING         String readString   sb toString            fis close         catch  Exception e           finally           if  fis    null                fis   null                    below code is to write the file in to internal filesystem   FileOutputStream fos   null      try            fos   context openFileOutput fileName  Context MODE PRIVATE           fos write stringdatatobestoredinfile getBytes             fos flush            fos close           catch  Exception e           finally           if  fos    null                fos   null                    I think this will help you

User · Answer

public static void writeStringAsFile final String fileContents  String fileName        Context context   App instance getApplicationContext        try           FileWriter out   new FileWriter new File context getFilesDir    fileName            out write fileContents           out close          catch  IOException e            Logger logError TAG  e            public static String readFileAsString String fileName        Context context   App instance getApplicationContext        StringBuilder stringBuilder   new StringBuilder        String line      BufferedReader in   null       try           in   new BufferedReader new FileReader new File context getFilesDir    fileName             while   line   in readLine       null  stringBuilder append line          catch  FileNotFoundException e            Logger logError TAG  e         catch  IOException e            Logger logError TAG  e               return stringBuilder toString

User · Answer

Kotlin class FileReadWriteService        private var context Context    ContextHolder instance appContext      fun writeFileOnInternalStorage fileKey  String  sBody  String            val file   File context  filesDir   quot files quot           try               if   file exists                      file mkdir                             val fileToWrite   File file  fileKey              val writer   FileWriter fileToWrite              writer append sBody              writer flush               writer close             catch  e  Exception                Logger e classTag  e                       fun readFileOnInternalStorage fileKey  String   String           val file   File context  filesDir   quot files quot           var ret    quot  quot          try               if   file exists                      return ret                           val fileToRead   File file  fileKey              val reader   FileReader fileToRead              ret   reader readText               reader close             catch  e  Exception                Logger e classTag  e                    return ret

User · Answer

The Kotlin way by using builtin Extension function on File Write  yourFile writeText textFromEditText  Read  yourFile readText

User · Answer

Just a a bit modifications on reading string from a file method for more performance  private String readFromFile Context context  String fileName        if  context    null            return null             String ret            try           InputStream inputStream   context openFileInput fileName            if   inputStream    null                 InputStreamReader inputStreamReader   new InputStreamReader inputStream                               int size   inputStream available                char   buffer   new char size                inputStreamReader read buffer                inputStream close                ret   new String buffer                  catch  Exception e            e printStackTrace               return ret

User · Answer

I m a bit of a beginner and struggled getting this to work today   Below is the class that I ended up with  It works but I was wondering how imperfect my solution is  Anyway  I was hoping some of you more experienced folk might be willing to have a look at my IO class and give me some tips  Cheers   public class HighScore       File data   new File Environment getExternalStorageDirectory   getAbsolutePath     File separator       File file   new File data   highscore txt        private int highScore   0       public int readHighScore             try               BufferedReader br   new BufferedReader new FileReader file                try                   highScore   Integer parseInt br readLine                     br close                  catch  NumberFormatException   IOException e                    e printStackTrace                            catch  FileNotFoundException e                try                   file createNewFile                  catch  IOException ioe                    ioe printStackTrace                              e printStackTrace                      return highScore             public void writeHighScore int highestScore            try               BufferedWriter bw   new BufferedWriter new FileWriter file                bw write String valueOf highestScore                bw close              catch  IOException e                e printStackTrace

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