tl;dr I'm more used to writing command-line scripts that can just output based on the current working directory, so I'm unsure what directory to use for output files in a program that will be launched from a JAR.
Program Description:
My program builds an HTML file from data given to it from the rest of the program, and then is supposed to write it to a file that we'll call "Output.html" for simplicity.
Relevant Code:
public void outputHTML()
{
String output = buildHTML();
// Expanded to explain my confusion better
String fileDirectory = ""; // ???
String fileName = "Output.html";
String fullPath = fileDirectory + "\\" + fileName;
try (BufferedWriter writer = new BufferedWriter(new FileWriter(fullPath)))
{
writer.write(output);
writer.close();
} catch (IOException e)
{
System.out.println("File not found.");
e.printStackTrace();
}
}
Problem
I don't know what to put the file directory as. Usually I run my programs from the command line and use ".\\Output.txt" as my output path, but I don't know where to put it if it's being run from a JAR.
The desired file structure is as follows:
Encompassing Folder
Program.jar
output
Output.html
Or alternatively (not sure if this makes it easier to understand or harder):
main\
main\Program.jar
main\output\
main\output\Output.html
Everything I can find on SE only relates to reading files that are both immutable and internal, but I'm trying to output a non-static file to a location outside of my jar.
Can anyone help with this? Thanks!
Misc Details
I'm using Eclipse without Gradle currently, because I don't know what Gradle is and new things are scary. If this particular problem would be easier to solve with Gradle, let me know and I'll look up more about it.
EDIT:
Added syntax highlighting to code block.
Formatted everything a bit better
Changed title to be more descriptive
You can use an absolute path: e.g. fileDirectory = "\\project\\test\\main\\output";
using normal slash should also work even on Windows ("/project/test/main/output")
Or use a relative path - this will start from the current working directory (user directory), the one where the JVM was started in - e.g. fileDirectory = "main\\output";
I have a Jenkins job running. I just want to get all files. In every file name there is a Chinese letter. So the problem is now that Jenkins has problems reading in those files. Jenkins makes just "?" out of the Asian letter. The second problem is. Actually it is more than 100 files. But Jenkins only gives me 20 files. Maybe now a lot of files will look the same because of the question mark "?" .
Does anyone know how I can fix this. The problem only occurs on Jenkins ( running on Linux ) . On my local machine in Eclipse it works though.
File resourcePath = new File("resources/china_data/");
File[] files = resourcePath.listFiles();
for (final File file : files)
{
System.out.console(file.getName);
}
An alternative solution is to use the new java.nio.Path api in place of the java.io.File api
Also try setting the below in your code initially.
System.setProperty("sun.jnu.encoding","utf-8");
System.setProperty("file.encoding","UTF-8");
Assuming you are using System.out.println, this happens when the program runs with an ASCII locale:
$ cat Main.java
import java.util.*;
import java.io.*;
class Main {
public static void main(String[] args) throws Exception {
File resourcePath = new File("resources/china_data/");
File[] files = resourcePath.listFiles();
for (final File file : files)
{
System.out.println(file.getName());
}
}
}
$ javac Main.java
$ LC_CTYPE=C java Main
???????
When the program runs with a UTF-8 capable locale, either from the environment or configured through Java, you get the expected result:
$ LC_CTYPE=en_US.UTF-8 java Main
中华人民共和国
$ LC_CTYPE=C java -Dfile.encoding=UTF-8 Main
中华人民共和国
If you're not sure how to configure your server, you can also do this from within Java:
System.setOut(new PrintStream(System.out, true, "UTF-8"));
I am having a little issue trying to figure out the best solution to the my path problems. I am running a java test that I want to get two things.
The absolute location of the project
The absolute location to the current class file that is running
I want to proper / or \ being on the OS version so the folder structure stays intact. I am currently using this but it is not exactly what I am looking for
final String parentDir = System.getProperty("user.dir");
final String path = "src/test/java/" + method.getDeclaringClass()
.getCanonicalName().replaceAll("\\.", "/") + ".java";
Any help would be appreciated. Thanks
Update: I am trying to get the url of the precompiled code as I need access to the comments in the code. This may change some of your guys answers
Update 2: Ok I got it to work.
final String path = new File(getClass().getResource("/").getFile())
.getParent().split("target")[0] + "src/test/java/" + method
.getDeclaringClass().getCanonicalName()
.replaceAll("\\.", "/") + ".java";
Thanks Guys
Given that you are calling this from MyClass you should call
File directory = (new File(MyClass.class.getProtectionDomain().getCodeSource().getLocation().toURI().getPath())).getParentFile();
I had the same question once. In addition to Jatin's answer I had to add an toURI() to get the correct path on all platforms (Windows, etc.) and post 1.5 JVMs.
If say you are running from jar file:
new File(MyClass.class.getProtectionDomain().getCodeSource().getLocation().getPath()).getParent()+"/"
returns the folder containing the jar file.
Remove the .getParent() above to get path to the exact class file
I know that the system property "user.dir" returns the current working directory; the directory containing that file that is currently running.
I am wondering, how would I be able to go one step farther? I need to find the current working file. I am writing a little app that is kind of like an auto-updater, and I need to know the file that needs to be updated. For example, if I run a file from C:/test.jar I want to actually know, in code, that the current location of the file that is running is C:/test.jar so that I can write (new) data to it.
I've tried an approach like this:
ClassLoader loader = Test.class.getClassLoader();
System.out.println(loader.getResource("Test.class"));
However, it prints out:
3/5/12 7:50:16.914 PM [0x0-0x31031].com.apple.JarLauncher: rsrc:Test.class
(I am running this on a Mac - I got that line from the Console).
Any help is greatly appreciated. Thanks!
With credits to Fab in the following post:
Jar path+name from currently running jar
String path = Test.class.getProtectionDomain().getCodeSource().getLocation().getPath();
String decodedPath = URLDecoder.decode(path, "UTF-8");
This will print the current file's path.
File f = new File(MyClass.class.getProtectionDomain().getCodeSource().getLocation().toURI().getPath());
System.out.println(f.getPath());
I am trying to copy a file using the following code:
File targetFile = new File(targetPath + File.separator + filename);
...
targetFile.createNewFile();
fileInputStream = new FileInputStream(fileToCopy);
fileOutputStream = new FileOutputStream(targetFile);
byte[] buffer = new byte[64*1024];
int i = 0;
while((i = fileInputStream.read(buffer)) != -1) {
fileOutputStream.write(buffer, 0, i);
}
For some users the targetFile.createNewFile results in this exception:
java.io.IOException: The filename, directory name, or volume label syntax is incorrect
at java.io.WinNTFileSystem.createFileExclusively(Native Method)
at java.io.File.createNewFile(File.java:850)
Filename and directory name seem to be correct. The directory targetPath is even checked for existence before the copy code is executed and the filename looks like this: AB_timestamp.xml
The user has write permissions to the targetPath and can copy the file without problems using the OS.
As I don't have access to a machine this happens on yet and can't reproduce the problem on my own machine I turn to you for hints on the reason for this exception.
This can occur when filename has timestamp with colons, eg. myfile_HH:mm:ss.csv Removing colons fixed the issue.
Try this, as it takes more care of adjusting directory separator characters in the path between targetPath and filename:
File targetFile = new File(targetPath, filename);
I just encountered the same problem. I think it has to something do with write access permission. I got the error while trying to write to c:\ but on changing to D:\ everything worked fine.
Apparently Java did not have permission to write to my System Drive (Running Windows 7 installed on C:)
Here is the test program I use
import java.io.File;
public class TestWrite {
public static void main(String[] args) {
if (args.length!=1) {
throw new IllegalArgumentException("Expected 1 argument: dir for tmp file");
}
try {
File.createTempFile("bla",".tmp",new File(args[0]));
} catch (Exception e) {
System.out.println("exception:"+e);
e.printStackTrace();
}
}
}
Try to create the file in a different directory - e.g. "C:\" after you made sure you have write access to that directory. If that works, the path name of the file is wrong.
Take a look at the comment in the Exception and try to vary all the elements in the path name of the file. Experiment. Draw conclusions.
Remove any special characters in the file/folder name in the complete path.
Do you check that the targetPath is a directory, or just that something exists with that name? (I know you say the user can copy it from the operating system, but maybe they're typing something else).
Does targetPath end with a File.separator already?
(It would help if you could log and tell us what the value of targetPath and filename are on a failing case)
Maybe the problem is that it is copying the file over the network, to a shared drive? I think java can have problems when writing files using NFS when the path is something like \mypc\myshared folder.
What is the path where this problem happens?
Try adding some logging to see exactly what is the name and path the file is trying to create, to ensure that the parent is well a directory.
In addition, you can also take a look at Channels instead of using a loop. ;-)
You say "for some users" - so it works for others? What is the difference here, are the users running different instances on different machines, or is this a server that services concurrent users?
If the latter, I'd say it is a concurrency bug somehow - two threads check try to create the file with WinNTFileSystem.createFileExclusively(Native Method) simultaniously.
Neither createNewFile or createFileExclusively are synchronized when I look at the OpenJDK source, so you may have to synchronize this block yourself.
Maybe the file already exists. It could be the case if your timestamp resolution is not good enough. As it is an IOException that you are getting, it might not be a permission issue (in which case you would get a SecurityException).
I would first check for file existence before trying to create the file and try to log what's happening.
Look at public boolean createNewFile() for more information on the method you are using.
As I was not able to reproduce the error on my own machine or get hands on the machine of the user where the code failed I waited until now to declare an accepted answer.
I changed the code to the following:
File parentFolder = new File(targetPath);
... do some checks on parentFolder here ...
File targetFile = new File(parentFolder, filename);
targetFile.createNewFile();
fileInputStream = new FileInputStream(fileToCopy);
fileOutputStream = new FileOutputStream(targetFile);
byte[] buffer = new byte[64*1024];
int i = 0;
while((i = fileInputStream.read(buffer)) != -1) {
fileOutputStream.write(buffer, 0, i);
}
After that it worked for the user reporting the problem.
So it seems Alexanders answer did the trick - although I actually use a slightly different constructor than he gave, but along the same lines.
I yet have to talk that user into helping me verifying that the code change fixed the error (instead of him doing something differently) by running the old version again and checking if it still fails.
btw. logging was in place and the logged path seemed ok - sorry for not mentioning that. I took that for granted and found it unnecessarily complicated the code in the question.
Thanks for the helpful answers.
A very similar error:-
" ... java.io.IOException: The filename, directory name, or volume label syntax is incorrect"
was generated in Eclipse for me when the TOMCAT home setting had a training backslash.
The minor edit suggested at:-
http://www.coderanch.com/t/556633/Tomcat/java-io-IOException-filename-directory
fixed it for me.
FileUtils.copyFile(src,new File("C:\\Users\\daiva\\eclipse-workspace\\PracticeProgram\\Screenshot\\adi.png"));
Try to copy file like this.