I am using enumeratefiles to list all the files in a directory. Its throws an exception when it encounters a filename containing illegal characters and then stops the foreach loop that is listing the files. How can I make the foreach loop continue listing out filenames despite the exception? Any ideas?
Code:
try {
DirectoryInfo directory = new DirectoryInfo(targetPath);
IEnumerable<FileInfo> allfiles = directory.EnumerateFiles("*.*", SearchOption.AllDirectories);
foreach (FileInfo file in allfiles)
{
Console.WriteLine(file.Name);
}
}
catch (ArgumentException o)
{
Console.WriteLine("Error: {0}", o.Message);
}
You have the try catch around the foreach loop. This means that if any one of the calls inside the loop fails your code will abort the rest of the loop.
Change the code to be something like this:
foreach (FileInfo file in allfiles)
{
try
{
Console.WriteLine(file.Name);
}
catch (ArgumentException o)
{
Console.WriteLine("Error: {0}", o.Message);
}
}
You still should have the try ... catch around the EnumerateFiles in case that throws an error.
Related
I have a log() method to avoid try catch statement in forEach() below which was working in other code.
public <T> Consumer<T> log(LogConsumer<T, Throwable> logConsumer)
{
return i -> {
try
{
logConsumer.accept(i);
}
catch (Throwable e)
{
log("e = " + e);
}
};
}
#FunctionalInterface
public interface LogConsumer<T, E extends Throwable> {
void accept(T t) throws E;
}
Now I just want to use log in forEach below but I have the red rippled line in LINE such that
new Task.runJob(job, type))
I have red rippled line under job, type in
"runJob(Job, JobType) in Task cannot be applied to (java.lang.Object, < lambda parameter>)"
Now sure how to fix it to use log in forEach just to avoid
try-catch inside of it.
execute() {
Map<Job, JobType> map = getJobMap();
map.forEach( log((job, type)-> new Taks().runJob(job,type)) ); // LINE: error here
}
class Task {
public String runJob(Job job, JobType type) throws Exception
{
...
return result;
}
}
It happens because you cannot execute functions that throw exceptions using lambda expressions. You have to handle the exception using try-catch block. However, in order for your code to look more readable, create a function, that will handle the exception and return the desired result.
class Task {
public String runJob(Job job, JobType type)
{
try {
...
return result;
} catch (Exception e) {
log.error(e.getMessage());
}
return null;
}
}
In case if you care what will be the result, map it and filter for the result of your function is not null, otherwise, ignore it, but watch logs for any errors.
And then call it like shown below.
Notice: both ways work below, but the second way is more robust because you can handle the scenario when not all jobs were executed without exception.
execute() {
Map<Job, JobType> map = getJobMap();
// First way
map.forEach( log((job, type) -> new Taks().runJob(job,type)) );
// Another way
List<Object> batchResult = map.entrySet().stream()
.map((job, type) -> new Task().runJob(jon, type))
.filter(Objects::nonNull)
.collect(Collectors.toList());
if (batchResult.size() == map.size()) {
// everythings is ok (all operations resulted in non-null result
} else {
// Have to study logs and figure out what went wrong
}
}
I am unable to cleanup the temporary file after the user uploads a file using
MultipartFormDataStreamProvider. I get "access to the path '...' is denied". However, it can delete old temporary files.
I based my cleanup on the example given here MultipartFormDataStreamProvider Cleanup.
I checked the windows identity and it has Read&Execute/read/write access to the folder. I think, something has locked by the file somehow, but I can't tell what. I tried moving the delete to the end and adding a sleep, but neither helped.
What is the correct way to cleanup these files? I need to do it immediately after I am done using the file. There really should be a setting so it does it for you.
[HttpPost]
[Route("UploadFile")]
public async Task<HttpResponseMessage> UploadFile(string toolToken,
int Publication_ID,
string externalKey,
int dataTypeID,
int toolProject_ID,
string cngDesc)
{
Logger logger = LogManager.GetCurrentClassLogger();
logger.Info("application pool user - " + System.Security.Principal.WindowsIdentity.GetCurrent().Name);
try
{
string tempDir = Config.ServerTempDataDir; // is ~/App_Data";
var provider = new MultipartFormDataStreamProvider(tempDir); //using this instead of ReadAsMultipartAsync because of memory constraints
await Request.Content.ReadAsMultipartAsync(provider);
MultipartFileData file = provider.FileData.FirstOrDefault(); //only one file is sent
if (file != null)
{
var dir = Path.GetDirectoryName(file.LocalFileName);
string begStr = Path.GetFileName(file.LocalFileName).Substring(0, 8);
//will do something with file
//delete file this fails every time, access denied
try
{
File.Delete(file.LocalFileName);
}
catch (Exception e)
{
logger.Error("Cleanup Failed" + e.Message);
return Request.CreateErrorResponse(HttpStatusCode.InternalServerError, e.Message);
}
//delete any lingering files - this works
foreach (var curFilePath in Directory.GetFiles(dir, begStr + "*"))
{
if (File.GetCreationTime(curFilePath) < (DateTime.Now.AddHours(-3)))
{
try
{
File.Delete(curFilePath);
}
catch { }
}
}
}
var response = Request.CreateResponse(HttpStatusCode.OK);
response.Content.Headers.ContentType = new MediaTypeWithQualityHeaderValue(#"application/json");
return response;
}
catch (Exception e)
{
logger.Error("Upload File Exception" + e.Message);
return Request.CreateErrorResponse(HttpStatusCode.InternalServerError, e.Message);
}
Our network guys had Read&Execute/read/write access but did not have "modify" access on the App_Data folder.
I searched around for this but I could not find a soultion.
Sorry about my bad description. Im not very good at this.
I have a UI class
Its calling a "lotto" class.
That lotto classes constructor is called a method named readData()
readData is reading from a file using BufferedReader
Im not getting an error message but its just not reading.
It gets stuck at BufferedReader fr = new BufferedReader... and goes to the catch thing.
If its a file not found problem how would i make it track where my file is. Im using eclipse and the program is stored on my usb. I need to hand it in to my teacher so i cant just put a location in. Is there code that tracks where my program is then takes the file from that folder?
Here is the code being used.
import java.io.*;
//contructor
public Lotto()
{
try
{
readData();
nc = new NumberChecker();
}
catch(IOException e)
{
System.out.println("There was a problem");
}
}
private void readData() throws IOException
{
//this method reads winning tickets date and pot from a file
BufferedReader file = new BufferedReader (new FileReader("data.txt"));
for(int i=0;i<5;i++)
{
System.out.println("in "+i);
winningNums[i] = file.readLine();
winningDates[i] = file.readLine();
weeksMoney[i] = Integer.parseInt(file.readLine());
System.out.println("out "+i);
}
file.close();
}
if you get an error in this line of code
BufferedReader file = new BufferedReader (new FileReader("data.txt"));
Then it is probably a FileNotFoundException
Make sure that the data.txt file is in the same folder as your compiled .class file and not the .java source.
It would be best to use a proper root to your file ex. c:\my\path\data.txt
And don't forget the \
Try surrounding the BufferedReader in a try catch and look for a file not found exception as well as IO exception. Also try putting in the fully qualified path name with double backslashes.
BufferedReader file;
try {
file = new BufferedReader (new FileReader("C:\\filepath\\data.txt"));
for(int i=0;i<5;i++)
{
System.out.println("in "+i);
winningNums[i] = file.readLine();
winningDates[i] = file.readLine();
weeksMoney[i] = Integer.parseInt(file.readLine());
System.out.println("out "+i);
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
I upload a file in my MVC 3 project.
[HttpPost]
public ActionResult MyUpload(HttpPostedFileBase file)
{
string filePath = string.Empty;
string path = "C:\\";
string filePath = string.Empty;
try
{
if (file != null && file.ContentLength > 0)
{
filePath = path + file.FileName;
file.SaveAs(filePath);
file.InputStream.Dispose();
GC.Collect();
// other operations, where can occur an exception
// (because the uploaded file can have a bad content etc.)
}
}
catch (Exception e)
{
if (file.InputStream != null)
file.InputStream.Dispose();
GC.Collect();
if (!string.IsNullOrEmpty(filePath))
{
if (System.IO.File.Exists(filePath))
System.IO.File.Delete(filePath); //here is the error
}
}
}
in that code, if an exception occured after I saved the file I can't delete it (also I cann't upload it again) because I get the error
The process cannot access the file
'[filePath]' because it is being used by another process.
What's wrong with that code ?
edit
I had to change the file.InputStream.Dispose(); to
file.InputStream.Close();
file.InputStream.Dispose();
file.InputStream = null;
And, now it's working fine.
Instead of checking if the file.InputStream is not null inside the catch block, you should dispose it inside the finally block, like this:
if (file != null && file.ContentLength > 0)
{
try
{
filePath = path + file.FileName;
file.SaveAs(filePath);
// other operations, where can occur an exception
// (because the uploaded file can have a bad content etc.)
}
catch (Exception e)
{
if (!string.IsNullOrEmpty(filePath))
{
if (System.IO.File.Exists(filePath))
System.IO.File.Delete(filePath); //here is the error
}
}
finally
{
file.InputStream.Close();
file.InputStream.Dispose();
GC.Collect();
}
}
By the way, the InputStream property is a read-only property. You can't set it to null.
I have researched and tried to refer back to my fileChooser.getSeletedFile() in my save as action but can not work out how to check whether or not a file has been created. Here is my attempted code so far:
Save as code(works well):
public void Save_As() {
fileChooserTest.setApproveButtonText("Save");
int actionDialog = fileChooserTest.showOpenDialog(this);
File fileName = new File(fileChooserTest.getSelectedFile() + ".txt");
try {
if (fileName == null) {
return;
}
BufferedWriter outFile = new BufferedWriter(new FileWriter(fileName));
outFile.write(this.jTextArea2.getText());//put in textfile
outFile.flush(); // redundant, done by close()
outFile.close();
} catch (IOException ex) {
}
}
"Save" code doesn't work:
private void SaveActionPerformed(java.awt.event.ActionEvent evt) {
File f = fileChooserTest.getSelectedFile();
try {
if (f.exists()) {
BufferedWriter bw1 = new BufferedWriter(new FileWriter(fileChooserTest.getSelectedFile() + ".txt"));
bw1 = new BufferedWriter(new FileWriter(fileChooserTest.getSelectedFile() + ".txt"));
String text = ((JTextArea) jTabbedPane1.getSelectedComponent()).getText();
bw1.write(text);
bw1.close();
} else {
Save_As();
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
Instead of storing an instance to the JFileChooser rather store an instance to the File (wich will be null before any save has been performed). In your SaveActionPerformed method check if the file is null. If it is null then do a Save_As and store the selected file in your file variable, if it is not null then do a normal save into the file.