Develop Reference

How do I delete a file stored in cache? (android)

I am not able delete file that is stored in cache. I am using the cache for several purposes. I am reading and writing but not able to delete. Can someone please help me with this?
//write
public static void writeObject(Context context, String key, Object object)
throws IOException {
Log.d("Cache", "WRITE: context");
FileOutputStream fos = context.openFileOutput(key, Context.MODE_PRIVATE);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(object);
oos.close();
fos.close();
}
//read
public static Object readObject(Context context, String key) throws IOException,
ClassNotFoundException {
FileInputStream fis = context.openFileInput(key);
ObjectInputStream ois = new ObjectInputStream(fis);
Object object = ois.readObject();
return object;
}
//delete
public static void clearCahe(String key) throws IOException,ClassNotFoundException {
File file = new File(key);
file.delete();
}

context.openFileOutput(key writes the file to internal memory. The path you can find with getFilesDir() and looks like /data/data/<yourpackagename>/files.
So if you want to delete the file 'key' you have to set up the path for File file = new File(path) as String path = getFilesDir().getAbsolutePath() + "/" + key;.
And use file.exists() to check if the file exists!

use this to clear application data.
public void clearApplicationData()
{
File cache = getCacheDir();
File appDir = new File(cache.getParent());
if (appDir.exists()) {
String[] children = appDir.list();
for (String s : children) {
if (!s.equals("lib")) {
deleteDir(new File(appDir, s));Log.i("TAG", "**************** File /data/data/APP_PACKAGE/" + s + " DELETED *******************");
}
}
}
}
public static boolean deleteDir(File dir)
{
if (dir != null && dir.isDirectory()) {
String[] children = dir.list();
for (int i = 0; i < children.length; i++) {
boolean success = deleteDir(new File(dir, children[i]));
if (!success) {
return false;
}
}
}
return dir.delete();
}

Files
Like the cache directory, your app also has an app-specific directory for holding files. Files in this directory will exist until the app explicitly deletes them or the app is uninstalled. You typically access this directory with Context.getFilesDir(). This can show up as various things on the app info screen, but in your screenshot this is "USB Storage Data".
NOTE: If you want to explicitly place on external media (typically SD card), you can use Context.getExternalFilesDir(String type).
Simple cache manager:
public class CacheManager {
private static final long MAX_SIZE = 5242880L; // 5MB
private CacheManager() {
}
public static void cacheData(Context context, byte[] data, String name) throws IOException {
File cacheDir = context.getCacheDir();
long size = getDirSize(cacheDir);
long newSize = data.length + size;
if (newSize > MAX_SIZE) {
cleanDir(cacheDir, newSize - MAX_SIZE);
}
File file = new File(cacheDir, name);
FileOutputStream os = new FileOutputStream(file);
try {
os.write(data);
}
finally {
os.flush();
os.close();
}
}
public static byte[] retrieveData(Context context, String name) throws IOException {
File cacheDir = context.getCacheDir();
File file = new File(cacheDir, name);
if (!file.exists()) {
// Data doesn't exist
return null;
}
byte[] data = new byte[(int) file.length()];
FileInputStream is = new FileInputStream(file);
try {
is.read(data);
}
finally {
is.close();
}
return data;
}
private static void cleanDir(File dir, long bytes) {
long bytesDeleted = 0;
File[] files = dir.listFiles();
for (File file : files) {
bytesDeleted += file.length();
file.delete();
if (bytesDeleted >= bytes) {
break;
}
}
}
private static long getDirSize(File dir) {
long size = 0;
File[] files = dir.listFiles();
for (File file : files) {
if (file.isFile()) {
size += file.length();
}
}
return size;
}
}
NOTE: The purpose of the cache is to cut down on network activity,
long processes, and provide a responsive UI in your app.
Reference: When to clear the cache dir in Android?.

Android basic TTS engine from audio file

I have an mp3 file hello.mp3. I am wrapping the mp3 into FileInputStream and converting the input stream to bytes, then pushing the bytes to SynthesisCallback.audioAvailable(bytes,offset,length) but this results to just noise.The file hello.mp3 plays just fine if I load it to my Android Music play.
Why is this not working when I push bytes from the file to SnthesisCallback? I have pasted my code below.
This is where I generate the Audio stream from mp3 file:
class AudioStream {
InputStream stream;
int length;
}
private AudioStream getAudioStream(String text) throws IOException {
// TODO parse text, and generate audio file.
File hello = new File(Environment.getExternalStorageDirectory(), "hello.mp3");
AudioStream astream = new AudioStream();
astream.length = hello.length();
astream.stream = new FileInputStream(hello);
return astream;
}
This is my Inputstream to byte[] method.
public byte[] inputStreamToByteArray(AudioStream inStream) throws IOException {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[inStream.length];
int bytesRead;
while ((bytesRead = inStream.stream.read(buffer)) > 0) {
baos.write(buffer, 0, bytesRead);
}
return baos.toByteArray();
}
This is my onSynthesizeText method in my TextToSpeechService class.
#Override
protected synchronized void onSynthesizeText(SynthesisRequest request,
SynthesisCallback callback) {
// TODO load language and other checks.
// At this point, we have loaded the language
callback.start(16000,
AudioFormat.ENCODING_PCM_16BIT, 1 /* Number of channels. */);
final String text = request.getText().toLowerCase();
try {
Log.i(TAG, "Getting audio stream for text "+text);
AudioStream aStream = getAudioStream(text);
byte[] bytes = inputStreamToByteArray(aStream);
final int maxBufferSize = callback.getMaxBufferSize();
int offset = 0;
while (offset < aStream.length) {
int bytesToWrite = Math.min(maxBufferSize, aStream.length - offset);
callback.audioAvailable(bytes, offset, bytesToWrite);
offset += bytesToWrite;
}
} catch (Exception e) {
e.printStackTrace();
callback.error();
}
// Alright, we're done with our synthesis - yay!
callback.done();
}
This is how I am testing my synthesis-engine-in the making.
//initialize text speech
textToSpeech = new TextToSpeech(this, new OnInitListener() {
/**
* a callback to be invoked indicating the completion of the TextToSpeech
* engine initialization.
*/
#Override
public void onInit(int status) {
if (status == TextToSpeech.SUCCESS) {
int result = textToSpeech.setLanguage(Locale.US);
if (result == TextToSpeech.LANG_MISSING_DATA || result == TextToSpeech.LANG_NOT_SUPPORTED) {
Log.e("error", "Language is not supported");
} else {
convertToSpeech("Hello");
}
} else {
Log.e("error", "Failed to Initilize!");
}
}
/**
* Speaks the string using the specified queuing strategy and speech parameters.
*/
private void convertToSpeech(String text) {
if (null == text || "".equals(text)) {
return;
}
textToSpeech.speak(text, TextToSpeech.QUEUE_FLUSH, null);
}
});

The function audioAvailable(byte[] buffer, int offset, int length) expects PCM samples as input. You cannot read bytes from .mp3 file and use it as input to the function. You need to use .wav file or first convert .mp3 file to .wav file and use it as input to audioAvailable function.

How to copy file from one location to another location?

I want to copy a file from one location to another location in Java. What is the best way to do this?
Here is what I have so far:
import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.List;
public class TestArrayList {
public static void main(String[] args) {
File f = new File(
"D:\\CBSE_Demo\\Demo_original\\fscommand\\contentplayer\\config");
List<String>temp=new ArrayList<String>();
temp.add(0, "N33");
temp.add(1, "N1417");
temp.add(2, "N331");
File[] matchingFiles = null;
for(final String temp1: temp){
matchingFiles = f.listFiles(new FilenameFilter() {
public boolean accept(File dir, String name) {
return name.startsWith(temp1);
}
});
System.out.println("size>>--"+matchingFiles.length);
}
}
}
This does not copy the file, what is the best way to do this?

You can use this (or any variant):
Files.copy(src, dst, StandardCopyOption.REPLACE_EXISTING);
Also, I'd recommend using File.separator or / instead of \\ to make it compliant across multiple OS, question/answer on this available here.
Since you're not sure how to temporarily store files, take a look at ArrayList:
List<File> files = new ArrayList();
files.add(foundFile);
To move a List of files into a single directory:
List<File> files = ...;
String path = "C:/destination/";
for(File file : files) {
Files.copy(file.toPath(),
(new File(path + file.getName())).toPath(),
StandardCopyOption.REPLACE_EXISTING);
}

Update:
see also
https://stackoverflow.com/a/67179064/1847899
Using Stream
private static void copyFileUsingStream(File source, File dest) throws IOException {
InputStream is = null;
OutputStream os = null;
try {
is = new FileInputStream(source);
os = new FileOutputStream(dest);
byte[] buffer = new byte[1024];
int length;
while ((length = is.read(buffer)) > 0) {
os.write(buffer, 0, length);
}
} finally {
is.close();
os.close();
}
}
Using Channel
private static void copyFileUsingChannel(File source, File dest) throws IOException {
FileChannel sourceChannel = null;
FileChannel destChannel = null;
try {
sourceChannel = new FileInputStream(source).getChannel();
destChannel = new FileOutputStream(dest).getChannel();
destChannel.transferFrom(sourceChannel, 0, sourceChannel.size());
}finally{
sourceChannel.close();
destChannel.close();
}
}
Using Apache Commons IO lib:
private static void copyFileUsingApacheCommonsIO(File source, File dest) throws IOException {
FileUtils.copyFile(source, dest);
}
Using Java SE 7 Files class:
private static void copyFileUsingJava7Files(File source, File dest) throws IOException {
Files.copy(source.toPath(), dest.toPath());
}
Or try Googles Guava :
https://github.com/google/guava
docs:
https://guava.dev/releases/snapshot-jre/api/docs/com/google/common/io/Files.html

Use the New Java File classes in Java >=7.
Create the below method and import the necessary libs.
public static void copyFile( File from, File to ) throws IOException {
Files.copy( from.toPath(), to.toPath() );
}
Use the created method as below within main:
File dirFrom = new File(fileFrom);
File dirTo = new File(fileTo);
try {
copyFile(dirFrom, dirTo);
} catch (IOException ex) {
Logger.getLogger(TestJava8.class.getName()).log(Level.SEVERE, null, ex);
}
NB:- fileFrom is the file that you want to copy to a new file fileTo in a different folder.
Credits - #Scott: Standard concise way to copy a file in Java?

public static void copyFile(File oldLocation, File newLocation) throws IOException {
if ( oldLocation.exists( )) {
BufferedInputStream reader = new BufferedInputStream( new FileInputStream(oldLocation) );
BufferedOutputStream writer = new BufferedOutputStream( new FileOutputStream(newLocation, false));
try {
byte[] buff = new byte[8192];
int numChars;
while ( (numChars = reader.read( buff, 0, buff.length ) ) != -1) {
writer.write( buff, 0, numChars );
}
} catch( IOException ex ) {
throw new IOException("IOException when transferring " + oldLocation.getPath() + " to " + newLocation.getPath());
} finally {
try {
if ( reader != null ){
writer.close();
reader.close();
}
} catch( IOException ex ){
Log.e(TAG, "Error closing files when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() );
}
}
} else {
throw new IOException("Old location does not exist when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() );
}
}

Copy a file from one location to another location means,need to copy the whole content to another location.Files.copy(Path source, Path target, CopyOption... options) throws IOException this method expects source location which is original file location and target location which is a new folder location with destination same type file(as original).
Either Target location needs to exist in our system otherwise we need to create a folder location and then in that folder location we need to create a file with the same name as original filename.Then using copy function we can easily copy a file from one location to other.
public static void main(String[] args) throws IOException {
String destFolderPath = "D:/TestFile/abc";
String fileName = "pqr.xlsx";
String sourceFilePath= "D:/TestFile/xyz.xlsx";
File f = new File(destFolderPath);
if(f.mkdir()){
System.out.println("Directory created!!!!");
}
else {
System.out.println("Directory Exists!!!!");
}
f= new File(destFolderPath,fileName);
if(f.createNewFile()) {
System.out.println("File Created!!!!");
} else {
System.out.println("File exists!!!!");
}
Files.copy(Paths.get(sourceFilePath), Paths.get(destFolderPath, fileName),REPLACE_EXISTING);
System.out.println("Copy done!!!!!!!!!!!!!!");
}

You can do it with the Java 8 Streaming API, PrintWriter and the Files API
try (PrintWriter pw = new PrintWriter(new File("destination-path"), StandardCharsets.UTF_8)) {
Files.readAllLines(Path.of("src/test/resources/source-file.something"), StandardCharsets.UTF_8)
.forEach(pw::println);
}
If you want to modify the content on-the-fly while copying, check out this link for the extended example https://overflowed.dev/blog/copy-file-and-modify-with-java-streams/

I modified one of the answers to make it a bit more efficient.
public void copy(){
InputStream in = null;
try {
in = new FileInputStream(Files);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
try {
OutputStream out = new FileOutputStream();
try {
// Transfer bytes from in to out
byte[] buf = new byte[1024];
while (true) {
int len = 0;
try {
if (!((len = in.read(buf)) > 0)) break;
} catch (IOException e) {
e.printStackTrace();
}
try {
out.write(buf, 0, len);
} catch (IOException e) {
e.printStackTrace();
}
}
} finally {
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
} finally {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void moveFile() {
copy();
File dir = getFilesDir();
File file = new File(dir, "my_filename");
boolean deleted = file.delete();
}

Files.exists()
Files.createDirectory()
Files.copy()
Overwriting Existing Files:
Files.move()
Files.delete()
Files.walkFileTree()
enter link description here

You can use
FileUtils.copy(sourceFile, destinationFile);
https://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/FileUtils.html

Copying children files of a source to a destination in Java

I'm trying to make a program that copies a directory's children, and I can't label all the specific names because they vary throughout each folder. Here's the code I have, but if the source is "C:\src" and the output is "C:\dst" it'll create the folder "C:\dst\src(children files)", but I want to make "C:\dst(children files)". Can anyone help?
public static void copy(File source, File destination) throws IOException {
if (source == null) {
throw new NullPointerException("Null Source");
}
if (destination == null) {
throw new NullPointerException("Null Destination");
}
if (source.isDirectory()) {
copyDirectory(source, destination);
} else {
copyFile(source, destination);
}
}
//converts to location
public static void copyDirectory(File source, File destination) throws IOException {
copyDirectory(source, destination, null);
}
public static void copyDirectory(File source, File destination, FileFilter filter) throws IOException {
File nextDirectory = new File(destination, source.getName());
if (!nextDirectory.exists() && !nextDirectory.mkdirs()) {// create the directory if necessary...
Object[] filler = {nextDirectory.getAbsolutePath()};
String message = "Dir Copy Failed";
throw new IOException(message);
}
File[] files = source.listFiles();
for (int n = 0; n < files.length; ++n) {// and then all the items below the directory...
if (filter == null || filter.accept(files[n])) {
if (files[n].isDirectory()) {
copyDirectory(files[n], nextDirectory, filter);
} else {
copyFile(files[n], nextDirectory);
}
}
}
}
public static void copyFile(File source, File destination) throws IOException {
// what we really want to do is create a file with the same name in that dir
if (destination.isDirectory()) {
destination = new File(destination, source.getName());
}
FileInputStream input = new FileInputStream(source);
copyFile(input, destination);
}
public static void copyFile(InputStream input, File destination) throws IOException {
OutputStream output = null;
try {
output = new FileOutputStream(destination);
byte[] buffer = new byte[1024];
int bytesRead = input.read(buffer);
while (bytesRead >= 0) {
output.write(buffer, 0, bytesRead);
bytesRead = input.read(buffer);
}
} catch (Exception e) {
//
} finally {
input.close();
output.close();
}
input = null;
output = null;
}

Replace
if (source.isDirectory()) {
copyDirectory(source, destination);
} else {
copyFile(source, destination);
}
By
if (source.isDirectory()) {
for (File child : source.listFiles()) {
if (child.isDirectory()) {
copyDirectory(child, destination);
} else {
copyFile(child, destination);
}
}
} else {
copyFile(source, destination);
}

use getParentFile() to get the parent directory:
if (source.isDirectory()) {
copyDirectory(source, destination.getParentFile());
} else {
copyFile(source, destination.getParentFile());
}

You can do everything here in one line using commons-io library :
FileUtils.copyDirectory(src, dest);
see :
http://commons.apache.org/io/api-1.4/org/apache/commons/io/FileUtils.html#copyDirectory%28java.io.File,%20java.io.File%29
jar file : http://mvnrepository.com/artifact/commons-io/commons-io/2.4

Try this one. copying whole files in a folder from source to destination.
import java.io.*;
public class copydir
{
public static void main(String args[])
{
File srcFolder = new File("E://Paresh/programs/test");
File destFolder = new File("D://paresh");
if(!srcFolder.exists())
{
System.out.println("Directory does not exist.");
//just exit
System.exit(0);
}
else{
try{
copyDirectory(srcFolder,destFolder);
}
catch(IOException e)
{
e.printStackTrace();
//error, just exit
System.exit(0);
}
}
System.out.println("Done");
}
public static void copyDirectory(File src , File target) throws IOException
{
if (src.isDirectory())
{
if (!target.exists())
{
target.mkdir();
}
String[] children = src.list();
for (int i=0; i<children.length; i++)
{
copyDirectory(new File(src, children[i]),new File(target, children[i]));
}
}
// if Directory exists then only files copy
else
{
InputStream in = new FileInputStream(src);
OutputStream out = new FileOutputStream(target);
// Copy the bits from instream to outstream
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) > 0)
{
out.write(buf, 0, len);
}
in.close();
out.close();
}
}
}

Copy and rename file on different location

I have one file example.tar.gz and I need to copy it to another location with different name
example _test.tar.gz. I have tried with
private void copyFile(File srcFile, File destFile) throws IOException {
InputStream oInStream = new FileInputStream(srcFile);
OutputStream oOutStream = new FileOutputStream(destFile);
// Transfer bytes from in to out
byte[] oBytes = new byte[1024];
int nLength;
BufferedInputStream oBuffInputStream = new BufferedInputStream(oInStream);
while((nLength = oBuffInputStream.read(oBytes)) > 0) {
oOutStream.write(oBytes, 0, nLength);
}
oInStream.close();
oOutStream.close();
}
where
String from_path = new File("example.tar.gz");
File source = new File(from_path);
File destination = new File("/temp/example_test.tar.gz");
if(!destination.exists())
destination.createNewFile();
and then
copyFile(source, destination);
It doesn't work. The path is correct. It prints that the file exists. Can anybody help me?

Why to reinvent the wheel, just use FileUtils.copyFile(File srcFile, File destFile) , this will handle many scenarios for you

I would suggest Apache commons FileUtils or NIO (direct OS calls)
or Just this
Credits to Josh - standard-concise-way-to-copy-a-file-in-java
File source=new File("example.tar.gz");
File destination=new File("/temp/example_test.tar.gz");
copyFile(source,destination);
Updates:
Changed to transferTo from #bestss
public static void copyFile(File sourceFile, File destFile) throws IOException {
if(!destFile.exists()) {
destFile.createNewFile();
}
FileChannel source = null;
FileChannel destination = null;
try {
source = new RandomAccessFile(sourceFile,"rw").getChannel();
destination = new RandomAccessFile(destFile,"rw").getChannel();
long position = 0;
long count = source.size();
source.transferTo(position, count, destination);
}
finally {
if(source != null) {
source.close();
}
if(destination != null) {
destination.close();
}
}
}

There is Files class in package java.nio.file. You can use the copy method.
Example: Files.copy(sourcePath, targetPath).
Create a targetPath object (which is an instance of Path) with the new name of your file.