placing a input file relative to program - java

In my program (simple plain cosole app) I am reading a file a.txt.
Now I will be giving the program to someone else and he should be able to run it. I don't want the file path to be fixed like D:\a.txt , instead it should be relative to my program. Where should I place the file so that my program always finds it?
File file = new File("D:\aks.txt");
FileReader fileReader = new FileReader(file);
BufferedReader bufferedReader = new BufferedReader(fileReader);
while( (str= bufferedReader.readLine())!=null){
}
My code is working fine when I hard code the path like D:\a.txt

Put the file in the classpath (e.g. the package root or in a certain package) and just get it straight from the classpath as follows
InputStream input = getClass().getResourceAsStream("/a.txt");
// ... (continue with InputStreamReader and so on)
(the exact path depends on the location of the current class and whether you prefix with / to start from package root and which classloader you're using)
Package and distribute it as a single executabele JAR file.
See also:
Java: Pathnames not working once I export to JAR

Related

How to read a file that i created inside my the same package?

This is a chunk of data I'd like to access by a method.
I'm doing the following to read my file:
String fileName = "file.txt"
InputStream inputStream = new FileInputStream(fileName);
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
My file.txt is in the same package, but I still get FileNotFoundException.
I didn't use a path url to point to the file because I thought since this it going to be an android application, hard-coding the path might not work when deployed... Please correct me if I am wrong. Thanks bunch!
This shows how to do that. https://stackoverflow.com/a/14377185/2801237
Also the 'package' your class is in has nothing to do with the 'path' where the file is being executed from. (two different concepts, 'package' = folder hierarchy of java source code files), 'path' = location on a filesystem of a specific file, your APK is being 'executed' in a particular place, and the location it writes a file is associated with that (I actually don't know where 'offhand' it writes by default, because I always get cache dir, or sd card root, etc.)
You may use:
InputStream inputStream = this.getClass().getResourceAsStream(fileName);

Reading a text file from expected path in java

I want to read a file from directory.File is in root directory. If i use path as E:\Java\Netbeans_practice\project_141\Description.txt then it works fine.But when i wanted to use path as the file name or within a defined folder as Info\Description.txt , it gives error (java.io.FileNotFoundException: Description.txt (The system cannot find the file specified)). Actually i don't want to use the path name before project directory (ex: E:\Java\Netbeans_practice\project_141).I have searched a lot but unable to solve.Please help me. Here is my portion of code :
Scanner in = new Scanner(new FileReader("Description.txt");
while(in.hasNextLine()){
out.print("* "+in.nextLine()+"<br>");
}
When you deploy your web app, only the contents inside the "WebContent" will be deployed. You can verify this by going to (assuming you are using tomcat in your eclipse):
projectworkspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\<contextName>
So you may wanan copy your "Description.txt" file into "/WEB-INF" (for security sake) directory. Then you should be able to access it:
File file = new File(getServletContext().getRealPath("/WEB-INF/Description.txt"));
Update:
String path="/WEB-INF/Description.txt";
InputStream inputStream = this.getServletConfig().getServletContext().getResourceAsStream(path);
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));

The system cannot find the file specified in java

I am making a program that opens and reads a file.
This is my code:
import java.io.*;
public class FileRead{
public static void main(String[] args){
try{
File file = new File("hello.txt");
System.out.println(file.getCanonicalPath());
FileInputStream ft = new FileInputStream(file);
DataInputStream in = new DataInputStream(ft);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String strline;
while((strline = br.readLine()) != null){
System.out.println(strline);
}
in.close();
}catch(Exception e){
System.err.println("Error: " + e.getMessage());
}
}
}
but when I run, I get this error:
C:\Users\User\Documents\Workspace\FileRead\hello.txt
Error: hello.txt (The system cannot find the file specified)
my FileRead.java and hello.txt where in the same directory that can be found in:
C:\Users\User\Documents\Workspace\FileRead
I'm wondering what I am doing wrong?
Try to list all files' names in the directory by calling:
File file = new File(".");
for(String fileNames : file.list()) System.out.println(fileNames);
and see if you will find your files in the list.
I have copied your code and it runs fine.
I suspect you are simply having some problem in the actual file name of hello.txt, or you are running in a wrong directory. Consider verifying by the method suggested by #Eng.Fouad
You need to give the absolute pathname to where the file exists.
File file = new File("C:\\Users\\User\\Documents\\Workspace\\FileRead\\hello.txt");
In your IDE right click on the file you want to read and choose "copy path"
then paste it into your code.
Note that windows hides the file extension so if you create a text file "myfile.txt" it might be actually saved as "myfile.txt.txt"
Generally, just stating the name of file inside the File constructor means that the file is located in the same directory as the java file. However, when using IDEs like NetBeans and Eclipse i.e. not the case you have to save the file in the project folder directory. So I think checking that will solve your problem.
How are you running the program?
It's not the java file that is being ran but rather the .class file that is created by compiling the java code. You will either need to specify the absolute path like user1420750 says or a relative path to your System.getProperty("user.dir") directory. This should be the working directory or the directory you ran the java command from.
First Create folder same as path which you Specified. after then create File
File dir = new File("C:\\USER\\Semple_file\\");
File file = new File("C:\\USER\\Semple_file\\abc.txt");
if(!file.exists())
{
dir.mkdir();
file.createNewFile();
System.out.println("File,Folder Created.);
}
When you run a jar, your Main class itself becomes args[0] and your filename comes immediately after.
I had the same issue: I could locate my file when provided the absolute path from eclipse (because I was referring to the file as args[0]). Yet when I run the same from jar, it was trying to locate my main class - which is when I got the idea that I should be reading my file from args[1].

Getting error saying file won't open in Java...any idea why this is happening?

I think I am really close, but I am unable to open a file I have called LocalNews.txt. Error says can't find file specified.
String y = "LocalNews.txt";
FileInputStream fstream = new FileInputStream(y);
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
Name of file is LocalNews.txt in library called News....anyone know why the file will not open?
The file is in the same Java Project that I am working on.
Error: LocalNews.txt (The system cannot find the file specified)
Project is named Bst, package is src in subPackage newsFinder, and library that the text files are stored in is called News.
Found out it was looking in
C:\EclipseIndigoWorkspace1\Bst\bin\LocalNews.txt
But I want it to look in (I believe)
C:\EclipseIndigoWorkspace1\Bst\News\LocalNews.txt
But if I make the above url a string, I get an error.
String y = "LocalNews.txt";
instead use
String y = "path from root/LocalNews.txt"; //I mean the complete path of the file
Your program can probably not find the file because it is looking in another folder.
Try using a absolute path like
String y = "c:\\temp\\LocalNews.txt";
By 'library called News' I assume you mean a jar file like News.jar which is on the classpath and contains the LocalNews.txt file you need. If this is the case, then you can get an InputStream for it by calling:
InputStream is = Thread.currentThread().getContextClassLoader()
.getResourceAsStream("LocalNews.txt");
Use
System.out.println(System.getProperty("user.dir") );
to find out what your current directory is. Then you'll know for sure whether your file is in the current directory or not. If it is not, then you have to specify the path so that it looks in the right directory.
Also, try this -
File file = new File (y);
System.out.println(file.getCanonicalPath());
This will tell you the exact path of your file on the system, provided your file is in the current directory. If it does not, then you know your file is not in the current directory.

Reading File In JAR using Relative Path

I have some text configuration file that need to be read by my program. My current code is:
protected File getConfigFile() {
URL url = getClass().getResource("wof.txt");
return new File(url.getFile().replaceAll("%20", " "));
}
This works when I run it locally in eclipse, though I did have to do that hack to deal with the space in the path name. The config file is in the same package as the method above. However, when I export the application as a jar I am having problems with it. The jar exists on a shared, mapped network drive Z:. When I run the application from command line I get this error:
java.io.FileNotFoundException: file:\Z:\apps\jar\apps.jar!\vp\fsm\configs\wof.txt
How can I get this working? I just want to tell java to read a file in the same directory as the current class.
Thanks,
Jonah
When the file is inside a jar, you can't use the File class to represent it, since it is a jar: URI. Instead, the URL class itself already gives you with openStream() the possibility to read the contents.
Or you can shortcut this by using getResourceAsStream() instead of getResource().
To get a BufferedReader (which is easier to use, as it has a readLine() method), use the usual stream-wrapping:
InputStream configStream = getClass().getResourceAsStream("wof.txt");
BufferedReader configReader = new BufferedReader(new InputStreamReader(configStream, "UTF-8"));
Instead of "UTF-8" use the encoding actually used by the file (i.e. which you used in the editor).
Another point: Even if you only have file: URIs, you should not do the URL to File-conversion yourself, instead use new File(url.toURI()). This works for other problematic characters as well.

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