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?.
Related
I have a program that should process the files in the directory and if the file size is more than 50 bytes delete it. Otherwise, if the file size is less then 50 bytes program should rename the args[1] file to the allFilesContent.txt(same directory), and write all the files to this file, separated by "n" (110 ASCII code). But instead the program just creates another file and writes to the very first args[1] file. What's the problem?
public class Solution
{
public static void main(String [] args) throws IOException
{
File path = new File(args[0]);
File resultFileAbsolutePath = new File(args[1]);
ArrayList<File> allFiles = new ArrayList<>();
boolean isRenamed = false;
for(File file : path.listFiles())
{
if(file.length() > 50)
{
FileUtils.deleteFile(file);
}
else if(file.length() <= 50)
{
if(!isRenamed)
{
FileUtils.renameFile(resultFileAbsolutePath, new File(resultFileAbsolutePath.getParent()+"\\allFilesContent.txt"));
isRenamed = true;
}
if(!file.getName().equals(resultFileAbsolutePath.getName()))
{
allFiles.add(file);
}
}
}
Collections.sort(allFiles, new Comparator<File>()
{
#Override
public int compare(File o1, File o2)
{
return o1.getName().compareTo(o2.getName());
}
});
FileOutputStream fileOutputStream = new FileOutputStream(resultFileAbsolutePath, true);
for (File file : allFiles)
{
try(FileInputStream fileInputStream = new FileInputStream(file))
{
if(allFiles.indexOf(file) != 0) fileOutputStream.write(110);
int data;
while(fileInputStream.available() > 0)
{
data = fileInputStream.read();
fileOutputStream.write(data);
}
}
}
fileOutputStream.close();
}
public static void deleteFile(File file)
{
if (!file.delete())
{
System.out.println("Can not delete file with name " + file.getName());
}
}
}
And FileUtils class
import java.io.File;
public class FileUtils
{
public static void deleteFile(File file)
{
if (!file.delete())
{
System.out.println("Can not delete file with name " + file.getName());
}
}
public static void renameFile(File source, File destination)
{
if (!source.renameTo(destination))
{
System.out.println("Can not rename file with name " + source.getName());
}
}
}
You have following statement: "FileOutputStream fileOutputStream = new FileOutputStream(resultFileAbsolutePath, true);"
Instead of "true" put "false". It should work.
So I have been working with a Derby DB and can write to and work with the data. I'm now trying to pack it into a single archive file(jar). I can get it to pack and unpack with no issues. Well except one.
I can get it to pack into a jar but it has an extra folder depth. So if I pack up the directory that is named "December", and inside that archive I also get a "December" folder with the contents inside it. Is there a way I can remove that extra folder either in packing or unpacking?
I have tried to play with the file's name but if I mess with it I get errors saying it can't find the file after I renamed it. I tried this both before it's packed and while unpacking it. Closes I got was each file name in the main directory but all the files are 0kb. I even try to change the pack directory to "December*", but it didn't like that.
public class JarPack {
public static void pack(String name,String dir) throws FileNotFoundException, IOException{
System.out.println(dir);
Manifest manifest = new Manifest();
manifest.getMainAttributes().put(Attributes.Name.MANIFEST_VERSION, "1.0");
JarOutputStream target = new JarOutputStream(new FileOutputStream(name), manifest);
add(new File(dir), target);
target.close();
}
private static void add(File source, JarOutputStream target) throws IOException{
BufferedInputStream in = null;
try
{
if (source.isDirectory())
{
String name = source.getPath().replace("\\", "/");
if (!name.isEmpty())
{
if (!name.endsWith("/"))
name += "/";
JarEntry entry = new JarEntry(name);
entry.setTime(source.lastModified());
target.putNextEntry(entry);
target.closeEntry();
}
for (File nestedFile: source.listFiles())
add(nestedFile, target);
return;
}
JarEntry entry = new JarEntry(source.getPath().replace("\\", "/"));
entry.setTime(source.lastModified());
target.putNextEntry(entry);
in = new BufferedInputStream(new FileInputStream(source));
byte[] buffer = new byte[1024];
while (true)
{
int count = in.read(buffer);
if (count == -1)
break;
target.write(buffer, 0, count);
}
target.closeEntry();
}
finally{
if (in != null)
in.close();
}
}
#SuppressWarnings("resource")
public static void unPack(String name,String dir) throws java.io.IOException {
java.util.jar.JarFile jarfile = new java.util.jar.JarFile(new java.io.File(name));
java.util.Enumeration<java.util.jar.JarEntry> enu= jarfile.entries();
while(enu.hasMoreElements()){
String destdir = dir;
java.util.jar.JarEntry je = enu.nextElement();
if (!je.getName().equals("META-INF/MANIFEST.MF")){
java.io.File fl = new java.io.File(destdir, je.getName());
if(!fl.exists()){
fl.getParentFile().mkdirs();
fl = new java.io.File(destdir, je.getName());
}
if(je.isDirectory()){
continue;
}
java.io.InputStream is = jarfile.getInputStream(je);
java.io.FileOutputStream fo = new java.io.FileOutputStream(fl);
while(is.available()>0){
fo.write(is.read());
}
fo.close();
is.close();
}
}
}
}
The code I have works for copying all direcotries and files but not sure on how to exclude a
particular directory under music and exclude a list of files
1) For example, I have Music folder and lots of subdirectories. Want to exclude spanish
subdirectory and copy everything under Music folder to destination
The second condition which I wanted to check is
2) Under Music folder I wanted to exclude all text files and copy
` private void copyFiles(File src, File tgt) throws IOException
{
if(src.isDirectory())
{
try{
if(!tgt.exists()) tgt.mkdirs();
String[] filePaths = src.list();
for(String filePath : filePaths)
{
File srcFile = new File(src, filePath);
File destFile = new File(tgt, filePath);
copyFiles(srcFile, destFile);
}
}
catch(Exception ie)
{
ie.printStackTrace();
}
}
else
{
try
{
bis = new BufferedInputStream(new FileInputStream(src));
bos = new BufferedOutputStream(new FileOutputStream(tgt));
long fileBytes = src.length();
long soFar = 0;
int Byte;
while((Byte = bis.read()) != -1)
{
bos.write(Byte);
}
bis.close();
bos.close();
}
catch(Exception excep)
{
excep.printStackTrace();
bos.flush();
bis.close();
bos.close();
}`
File#listFiles takes a FileFilter which can be used to determine if certain files should be included or not in the listing returne by File#listFiles...
This is okay if you know in advance what you to to include/exclude. If you want to make the process more dynamic, you could pass a list of FileFilters to the copy method and then use a special FileFilter to iterate over them...
private void copyFiles(File src, File tgt, FileFilter... filters) {
/*...*/
File[] filePaths = src.listFiles(new GroupedFileFiler(filters));
/*...*/
}
public class GroupedFileFilter implements FileFilter {
private FileFilter[] filters;
public GroupedFileFilter(FileFilter... filters) {
this.filters = filters;
}
#Override
public boolean accept(File pathname) {
boolean include = true;
if (filters != null && filters.length > 0) {
for (FileFilter filter : filters) {
include = filter.accept(pathname);
if (!include) {
break;
}
}
}
return include;
}
}
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
Im making a backup program, and I want everything that i have the program backing up displayed on a JTextArea. well, it works, but only after the program is finished with the backup. How do i fix this? The code i have running this is here:
backup method
public void startBackup() throws Exception {
// txtarea is the JTextArea
Panel.txtArea.append("Starting Backup...\n");
for (int i = 0; i < al.size(); i++) {
//al is an ArrayList that holds all of the backup assignments selected
// from the JFileChooser
File file = new File((String) al.get(i));
File directory = new File(dir);
CopyFolder.copyFolder(file, directory);
}
}
Copy Folder class:
public class CopyFolder {
public static void copyFolder(File src, File dest) throws IOException {
if (src.isDirectory()) {
// if directory not exists, create it
if (!dest.exists()) {
dest.mkdir();
Panel.txtArea.append("Folder " + src.getName()
+ " was created\n");
}
// list all the directory contents
String files[] = src.list();
for (String file : files) {
// construct the src and dest file structure
File srcFile = new File(src, file);
File destFile = new File(dest, file);
// recursive copy
copyFolder(srcFile, destFile);
}
} else {
try {
CopyFile.copyFile(src, dest);
} catch (Exception e) {
}
}
}
}
CopyFile class
public class CopyFile {
public static void copyFile(File src, File dest) throws Exception {
// if file, then copy it
// Use bytes stream to support all file types
InputStream in = new FileInputStream(src);
OutputStream out = new FileOutputStream(dest);
byte[] buffer = new byte[1024];
int length;
// copy the file content in bytes
while ((length = in.read(buffer)) > 0) {
out.write(buffer, 0, length);
}
in.close();
out.close();
// System.out.println("File copied from " + src + " to " + dest);
Panel.txtArea.append("File copied " + src.getName() + "\n");
}
}
Thanks for the help in advance, and let me know of any assistance i can give. I did a google search on this, and it does seem to be a big problem, but i just cant think of how to fix it. Oh, and please dont downvote this just because it doesnt apply to you, its very aggravating. Thanks in advance again!
EDIT:
This is what i got:
public class test extends SwingWorker<Void, String> {
String txt;
JTextArea txtArea = null;
public test(JTextArea txtArea, String str) {
txt = str;
this.txtArea = txtArea;
}
protected Void doInBackground() throws Exception {
return null;
}
protected void process(String str) {
txtArea.append(str);
}
protected void getString() {
publish(txt);
}
}
The main problem you're having is you're trying to perform blocking actions in the Event Dispatching Thread. This will prevent the UI from been updated as repaint requests are not reaching the repaint manager until AFTER you've finished.
To over come this, you're going to need to off load the blocking work (ie the back up process) to a separate thread.
For this I suggest you have a read through the Concurrency in Swing Trail which will provide you with some useful strategies to solve your particular problem. In particular, you'll probably benifit from using a SwingWorker
Take a close look at doInBackground and the process methods
UPDATED with Example
Okay, so this is a REALLY simple example. This basically walks you C:\ drive to 3 directories deep and dumps the content to the supplied JTextArea
public class BackgroundWorker extends SwingWorker<Object, File> {
private JTextArea textArea;
public BackgroundWorker(JTextArea textArea) {
this.textArea = textArea;
}
#Override
protected Object doInBackground() throws Exception {
list(new File("C:\\"), 0);
return null;
}
#Override
protected void process(List<File> chunks) {
for (File file : chunks) {
textArea.append(file.getPath() + "\n");
}
textArea.setCaretPosition(textArea.getText().length() - 1);
}
protected void list(File path, int level) {
if (level < 4) {
System.out.println(level + " - Listing " + path);
File[] files = path.listFiles(new FileFilter() {
#Override
public boolean accept(File pathname) {
return pathname.isFile();
}
});
publish(path);
for (File file : files) {
System.out.println(file);
publish(file);
}
files = path.listFiles(new FileFilter() {
#Override
public boolean accept(File pathname) {
return pathname.isDirectory() && !pathname.isHidden();
}
});
for (File folder : files) {
list(folder, level + 1);
}
}
}
}
You would simply call new BackgroundWorker(textField).execute() and walk away :D
UPDATED with explicit example
public class BackgroundWorker extends SwingWorker<Object, String> {
private JTextArea textArea;
private File sourceDir;
private File destDir;
public BackgroundWorker(JTextArea textArea, File sourceDir, File destDir) {
this.textArea = textArea;
this.sourceDir = sourceDir;
this.destDir = destDirl
}
#Override
protected Object doInBackground() throws Exception {
if (sourceDir.isDirectory()) {
// if directory not exists, create it
if (!destDir.exists()) {
destDir.mkdir();
publish("Folder " + sourceDir.getName() + " was created");
}
// list all the directory contents
String files[] = sourceDir.list();
for (String file : files) {
// construct the src and dest file structure
File srcFile = new File(sourceDir, file);
File destFile = new File(destDir, file);
// recursive copy
copyFolder(srcFile, destFile);
}
} else {
try {
copyFile(sourceDir, destDir);
} catch (Exception e) {
}
}
return null;
}
public void copyFolder(File src, File dest) throws IOException {
if (src.isDirectory()) {
// if directory not exists, create it
if (!dest.exists()) {
publish("Folder " + src.getName() + " was created");
}
// list all the directory contents
String files[] = src.list();
for (String file : files) {
// construct the src and dest file structure
File srcFile = new File(src, file);
File destFile = new File(dest, file);
// recursive copy
copyFolder(srcFile, destFile);
}
} else {
try {
copyFile(src, dest);
} catch (Exception e) {
}
}
}
public void copyFile(File src, File dest) throws Exception {
// if file, then copy it
// Use bytes stream to support all file types
InputStream in = new FileInputStream(src);
OutputStream out = new FileOutputStream(dest);
byte[] buffer = new byte[1024];
int length;
// copy the file content in bytes
while ((length = in.read(buffer)) > 0) {
out.write(buffer, 0, length);
}
in.close();
out.close();
publish("File copied " + src.getName());
}
#Override
protected void process(List<String> chunks) {
for (String msg : chunks) {
textArea.append(msg + "\n");
}
textArea.setCaretPosition(textArea.getText().length() - 1);
}
}
Now to run...
new BackgroundWorker(textArea, sourceDir, destDir).execute();