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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<String> getListOfFiles(String path) {
File files = new File(path);
FileFilter filter = new FileFilter() {
private final List<String> 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<String> list = new ArrayList<String>();
if (filesFound != null && filesFound.length > 0) {
for (File file : filesFound) {
list.add(file.getName());
return list;
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:
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
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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
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.
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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 < size) {
int remain = size - read;
while (remain > 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.
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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.
* Creates a InputStream for a file using the specified Context
* and returns the Bytes read from the file.
* @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;
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)) > 0) total += count;
return data;
catch (Exception ex)
ex.printStackTrace();
finally
if (input != null) try
input.close();
catch (Exception ex)
ex.printStackTrace();
return null;
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;
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());
To read a file in bytes, often used to read binary files, such as pictures, sounds, images, etc.
Use the method below.
public static byte[] readFileByBytes(File file) {
byte[] tempBuf = new byte[100];
int byteRead;
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
try {
BufferedInputStream bufferedInputStream = new BufferedInputStream(new FileInputStream(file));
while ((byteRead = bufferedInputStream.read(tempBuf)) != -1) {
byteArrayOutputStream.write(tempBuf, 0, byteRead);
bufferedInputStream.close();
return byteArrayOutputStream.toByteArray();
} catch (Exception e) {
e.printStackTrace();
return null;
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