We Keep Coding

Downloading status of a large file in Java

When a large file is coming to server, it's taking few minutes to complete the download. During that period, I don't want to read the file content. I want to know the status of the downloading, i.e. whether downloading has completed or not. Only after successful completion of downloading, I want to read the file. I have written this method, but it's not working. Please help.
// checking downloading completed or not
private boolean saveFile(String fileName, URL download)
static String fileName = "Teleradiology Demonstration-20130909 1233-1.mp4";
File myFile=new File("E:/dicom_server_storage"); // reading directory
// File myFile = new File("C:/Users/Subhojit/AppData/Roaming/Skype/My Skype Received Files");
URL download = myFile.toURI().toURL();
{
try
{
// String saveTo = System.getProperty("user.dir") + "\\dicom_server_storage";
String saveTo = "E:\\"; // save location
ReadableByteChannel rbc = Channels.newChannel(download.openStream());
FileOutputStream fos = new FileOutputStream(saveTo + fileName);
fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
fos.close();
System.out.println("File download successfully completed.");
return true;
}
catch (FileNotFoundException e)
{
e.printStackTrace();
}
catch (MalformedURLException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
return false;
}

Strange issue when creating a new file

I have the below 2 methods, supposed to read and write to a file:
/* Write content to a file */
private void writeToFile(ArrayList<String> list) {
#SuppressWarnings("unused")
File file = new File("jokesBody1.bjk");
FileOutputStream fos;
if(list != null){
try {
fos = openFileOutput("jokesBody1.bjk",Context.MODE_PRIVATE);
ObjectOutputStream out = new ObjectOutputStream(fos);
out.writeObject(list);
out.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}else{
try {
fos = openFileOutput("jokesBody1.bjk",Context.MODE_PRIVATE);
ObjectOutputStream out = new ObjectOutputStream(fos);
out.writeObject("");
out.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/* Read file's content */
private ArrayList<String> readFromFile() {
File file = new File("jokesBody1.bjk");
ArrayList<String> list = new ArrayList<String>();
try {
ObjectInputStream ois = new ObjectInputStream( new FileInputStream( file ) );
try {
list = (ArrayList)ois.readObject();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
ois.close();
} catch (IOException e) {
Log.e("log activity", "Can not read file: " + e.toString());
}
return list;
}
When I'm calling the above methods I'm getting this error:
02-15 10:28:48.165: E/log activity(1743): Can not read file: java.io.FileNotFoundException: /jokesBody1.bjk: open failed: ENOENT (No such file or directory)
Ok, it clearly says that the file is not there, but, isn't this code supposed to create it:
File file = new File("jokesBody1.bjk");
Why I'm getting this error? I know that I'm missing something small - probably a piece of code that creates the file(I'm not sure), but as a beginner, I'm not able to spot the issue.

File file = new File("jokesBody1.bjk");
Just creates a File objects that points to that path, but no actual file.
Use
file.createNewFile();
To actually create the file.

Ok, it clearly says that the file is not there, but, isn't this code supposed to create it:
Actually, no. It only creates a File object, an then java assumes that file to exist.

Writing and reading from txt file android

I know that this is a widely discussed question , but I am really confused with those examples provided on android developers manual .
So , I have a "source.txt" in my res/raw folder .For example I want to write 2 lines in it(for ex. Hello\nWorld) and then read them from another activity. Can anyone write the source code for this , please.

You should replace your .txt file to your extornal or internal storage.And You must give permission for write text from androidManifest.xml
for reading file you can do this
public String readFile(String filePath) {
String jString = null;
StringBuilder builder = new StringBuilder();
File yourFile = new File("/sdcard/" + filepath);
if (yourFile.exists()) {
Log.i("file", "file founded");
BufferedReader bufferedReader = null;
try {
bufferedReader = new BufferedReader(new FileReader(yourFile));
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String row = "";
try {
while ((row = bufferedReader.readLine()) != null) {
builder.append(row + "\n");
}
bufferedReader.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
jString = builder.toString();
}
else {
Log.i("FAIL", "FILE NOT FOUND");
}
return jString;
}
for writing file you can use this
public void writetoFile(String filename,String text) {
File file = new File("/sdcard/" + filename);
if (!file.exists())
try {
file.createNewFile();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
FileWriter fileWriter;
try {
//you can change second parametre true or false this is about append or clean and write
fileWriter = new FileWriter(file, false);
BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);
bufferedWriter.append(jsonText);
bufferedWriter.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

Whatever is in your APK file is read-only, therefore you are unable to write to file stored in res/raw source folder as it is still in your APK. if you want to work on file shipped with your app, you need to copy if to internal storage or SD card from APK first so that would allow you to alter the content.

Every file in your apk is read only, so you need to create the file in your internal storage or SD Card. If you just want to send small amount to of data to second activity, you can send data along with intent or use sharedPreference.
If you really want to read and write data to/from SD card then you need to use FileInputStream and OutputStreamWriter to read/write data to a file. Check this tutorial here to see how it's done. http://www.java-samples.com/showtutorial.php?tutorialid=1523

Why isn't a new created file local?

I have the problem, that I create a new file in a Java program, but I always get an exception, that the new created file is not local, when I try to open it on the eclipse project explorer view.
The code where I create it is as follows:
IWorkspaceRoot workspaceRoot = ResourcesPlugin.getWorkspace().getRoot();
IProject project = workspaceRoot.getProject(projectName);
FileUtil myFile = new FileUtil();
if (!project.getFile(FILE_NAME).exists()) {
IFile newFile = project.getFile("conf.txt");
FileInputStream fileStream = null;
try {
String temp = project + "/conf.txt";
temp = temp.substring(2);
fileStream = new FileInputStream(temp);
} catch (FileNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
newFile.create(fileStream, false, null);
} catch (CoreException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
// create closes the file stream, so no worries.
try {
myFile.writeTextFile(FILE_NAME, "Seconds", output);
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
FileUtil is a class which only implements the methods write and read for the file.
The Exception I get when I try to open it begins with:
org.eclipse.core.internal.resources.ResourceException: Resource '/ProjectE1/conf.txt' is not local.
at org.eclipse.core.internal.resources.Resource.checkLocal(Resource.java:353)
at org.eclipse.core.internal.resources.File.getContentDescription(File.java:264)
at org.eclipse.core.internal.propertytester.FilePropertyTester.testContentType(FilePropertyTester.java:108)
I somehow have to get a relative path during the runtime. Because I am opening a new instance of eclipse in the program, where I can see the Project in the Project Explorer but can't open the conf.txt file because it is not local.

It looks like your resource is an absolute path to /ProjectE1/conf.txt, I'm confused why you are not using java.io.
This will help you understand relative paths, I think this may be where you are wanting to put your conf file.
File file = new File("conf.txt");
if(!file.createNewFile()){
//err
}
System.out.println(file.getAbsolutePath());

I had similar issue. This is how I fixed.
First created file in local file system (using java.io)
Did project refresh
Reload the file
File file = new File(project.getWorkspace().getRoot().getLocation() + project.getFullPath().toString() + "/relative_path_of_my_file");
file.createNewFile();
project.refreshLocal(IProject.DEPTH_INFINITE, null);
keywordFile = project.getFile("/relative_path_of_my_file");

Create file in specified directory

Try to create file in specific directory but it shows the error FileNotFound. Why?
Am I using impossible path? I really don't know, but is seems like the code should be working.
String day=/1;
String zn="/zn";
File_name=zn
String root= Environment.getExternalStorageDirectory().toString();
File_path=root+day;
File file1 = new File(File_path,File_name);
file1.mkdirs();
if(!file1.exists()) {
try {
file1.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
try {
OutputStream fos= new FileOutputStream(file1);
String l,d,p;
l = lessnum.getText().toString();
d = desc.getText().toString();
p = place.getText().toString();
fos.write(l.getBytes());
fos.write(d.getBytes());
fos.write(p.getBytes());
fos.close();

Change your code as for creating a file on sdcard
String root= Environment.getExternalStorageDirectory().getAbsolutePath();
String File_name = "File_name.Any_file_Extension(like txt,png etc)";
File file1 = new File(root+ File.separator + File_name);
if(!file1.exists()) {
try {
file1.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
In current you you are also missing file Extension with file name so change String zn as zn="/zn.txt";
and make sure you have added Sd card permission in AndroidManifest.xml :
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

First you make a directory
String root= Environment.getExternalStorageDirectory().toString();
String dirName =
root+ "abc/123/xy";
File newFile = new File(dirName);
newFile.mkdirs();
then you create a file inside that directory
String testFile = "test.txt";
File file1 = new File(dirName,testFile);
if(!file1.exists()){
try {
file1.createNewFile();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
then do your file writing operations
try { OutputStream fos= new FileOutputStream(file1);
String l,d,p;
l = lessnum.getText().toString();
d = desc.getText().toString();
p = place.getText().toString();
os.write(l.getBytes());
fos.write(d.getBytes());
fos.write(p.getBytes());
fos.close();
}
catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
I think this will help you...
Thanks...

you will need to give your app the correct permission to write to the SD Card by adding the line below to your Manifest:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
And check http://developer.android.com/reference/android/os/Environment.html#getExternalStorageDirectory%28%29

String root= Environment.getExternalStorageDirectory().toString();
String dirName =
root+ "abc/123/xy";
File newFile = new File(dirName);
newFile.mkdirs();
String testFile = "test.txt";
File file1 = new File(dirName,testFile);
if(!file1.exists()){
try {
file1.createNewFile();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
And and <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
on manifest file...
Thanks...

Here is your latest attempt:
File_path = root + File.separator + day;
File f_dir = new File(File_path);
f_dir.mkdirs();
File file1 = new File(f_dir, File_name);
if (!file1.exists()) {
try {
file1.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
try {
OutputStream fos= new FileOutputStream(file1);
If you showed us the complete stacktrace and error message it would be easier to figure out what is going wrong, but I can think of a couple of possibilities:
You are not checking the value returned by f_dir.mkdirs(), and it could well be returning false to indicate that the directory path was not created. This could mean that:
The directory already existed.
Something existed but it wasn't a directory.
Some part of the directory path could not be created ... for one of a number of possible reasons.
The file1.exists() call will return true if anything exists with that pathname given by the object. The fact that something exists doesn't necessarily mean that you can open it for writing:
It could be a directory.
It could be a file that the application doesn't have write permissions for.
It could be a file on a read-only file system.
And a few other things.
If I was writing this, I'd write it something like this:
File dir = new File(new File(root), day);
if (!dir.exists()) {
if (!dir.mkdirs()) {
System.err.println("Cannot create directories");
return;
}
}
File file1 = new File(dir, fileName);
try (OutputStream fos= new FileOutputStream(file1)) {
...
} catch (FileNotFoundException ex) {
System.err.println("Cannot open file: " + ex.getMessage());
}
I only attempt to create the directory if required ... and check that the creation succeeded.
Then I simply attempt to open the file to write to it. If the file doesn't exist it will be created. If it cannot be created, then the FileNotFoundException message should explain why.
Notice that I've also corrected the style errors you made in your choice of variable names.