Android How to read file in bytes

Question

I am trying to get file content in bytes in Android application  I have get the file in SD card now want to get the selected file in bytes  I googled but no such success  Please help  Below is the code to get files with extension  Through this i get files and show in spinner  On file selection I want to get file in bytes   private List lt String gt  getListOfFiles String path        File files   new File path       FileFilter filter   new FileFilter            private final List lt String gt  exts   Arrays asList  jpeg    jpg    png    bmp    gif   mp3           public boolean accept File pathname             String ext           String path   pathname getPath             ext   path substring path lastIndexOf        1            return exts contains ext                     final File    filesFound   files listFiles filter      List lt String gt  list   new ArrayList lt String gt        if  filesFound    null  amp  amp  filesFound length  gt  0          for  File file   filesFound             list add file getName                     return list

User · Answer

You can also do it this way   byte   getBytes  File file        FileInputStream input   null      if  file exists    try               input   new FileInputStream  file           int len    int  file length            byte   data   new byte len           int count  total   0          while   count   input read  data  total  len - total    gt  0  total    count          return data            catch  Exception ex                ex printStackTrace              finally               if  input    null  try                       input close                      catch  Exception ex                        ex printStackTrace                        return null

User · Answer

Here is a solution that guarantees entire file will be read  that requires no libraries and is efficient   byte   fullyReadFileToBytes File f  throws IOException       int size    int  f length        byte bytes     new byte size       byte tmpBuff     new byte size       FileInputStream fis  new FileInputStream f        try            int read   fis read bytes  0  size           if  read  lt  size                int remain   size - read              while  remain  gt  0                    read   fis read tmpBuff  0  remain                   System arraycopy tmpBuff  0  bytes  size - remain  read                   remain -  read                                 catch  IOException e           throw e        finally           fis close               return bytes      NOTE  it assumes file size is less than MAX INT bytes  you can add handling for that if you want

User · Answer

A simple InputStream will do  byte   fileToBytes File file       byte   bytes   new byte 0       try FileInputStream inputStream   new FileInputStream file             bytes   new byte inputStream available               noinspection ResultOfMethodCallIgnored         inputStream read bytes         catch  IOException e            e printStackTrace              return bytes

User · Answer

The easiest solution today is to used Apache common io    http   commons apache org proper commons-io javadocs api-release org apache commons io FileUtils html readFileToByteArray java io File   byte bytes     FileUtils readFileToByteArray photoFile    The only drawback is to add this dependency in your build gradle app    implementation  commons-io commons-io 2 5      1562 Methods count

User · Answer

Since the accepted BufferedInputStream read isn t guaranteed to read everything  rather than keeping track of the buffer sizes myself  I used this approach       byte bytes     new byte  int  file length         BufferedInputStream bis   new BufferedInputStream new FileInputStream file        DataInputStream dis   new DataInputStream bis       dis readFully bytes     Blocks until a full read is complete  and doesn t require extra imports

User · Answer

here it s a simple   File file   new File path   int size    int  file length    byte   bytes   new byte size   try       BufferedInputStream buf   new BufferedInputStream new FileInputStream file        buf read bytes  0  bytes length       buf close      catch  FileNotFoundException e           TODO Auto-generated catch block     e printStackTrace      catch  IOException e           TODO Auto-generated catch block     e printStackTrace        Add permission in manifest xml     lt uses-permission android name  android permission READ EXTERNAL STORAGE    gt

User · Answer

Following is the working solution to read the entire file in chunks and its efficient solution to read the large files using a scanner class      try           FileInputStream fiStream   new FileInputStream inputFile name           Scanner sc   null          try               sc   new Scanner fiStream               while  sc hasNextLine                      String line   sc nextLine                    byte   buf   line getBytes                            finally               if  fiStream    null                    fiStream close                               if  sc    null                    sc close                                 catch  Exception e           Log e TAG   Exception      e toString

User · Answer

If you want to use a the openFileInput method from a Context for this  you can use the following code   This will create a BufferArrayOutputStream and append each byte as it s read from the file to it           lt p gt         Creates a InputStream for a file using the specified Context        and returns the Bytes read from the file      lt  p gt         param context The context to use      param file The file to read from      return The array of bytes read from the file  or null if no file was found      public static byte   read Context context  String file  throws IOException       byte   ret   null       if  context    null            try               InputStream inputStream   context openFileInput file               ByteArrayOutputStream outputStream   new ByteArrayOutputStream                 int nextByte   inputStream read                while  nextByte    -1                    outputStream write nextByte                   nextByte   inputStream read                               ret   outputStream toByteArray               catch  FileNotFoundException ignored                 return ret

[java] Android : How to read file in bytes?

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