Java, reading a file from current directory?

Question

I want a java program that reads a user specified filename from the current directory (the same directory where the .class file is run).

In other words, if the user specifies the file name to be "myFile.txt", and that file is already in the current directory:

reader = new BufferedReader(new FileReader("myFile.txt"));

does not work. Why?

I'm running it in windows.

Bega

This is same in Linux too – Liaotung

Answer 1

The current directory is not (necessarily) the directory the .class file is in. It's working directory of the process. (ie: the directory you were in when you started the JVM)

You can load files from the same directory^* as the .class file with getResourceAsStream(). That'll give you an InputStream which you can convert to a Reader with InputStreamReader.

---

_{^*Note that this "directory" may actually be a jar file, depending on where the class was loaded from.}

Holeproof

+1. If you're running an IDE like Eclipse or Idea, current directory will be the project directory, not the compiler output. – Wildee

@piiligrim, depends on your launch configuration – Valkyrie

@DenisTulskiy I am working on Eclipse as same coding as the example person did. Mine is still not working, Why is that? – Unconformable

Answer 2

Try

System.getProperty("user.dir")

It returns the current working directory.

Defunct

but it returns only the path till root directory of project. how we can get path of current package in main method of java – Charlatan

@TaimoorChangaiz, System.getProperty("user.dir") + "\\src\\main\\java\\" + "Winners.txt" – Solly

Answer 3

None of the above answer works for me. Here is what works for me.

Let's say your class name is Foo.java, to access to the myFile.txt in the same folder as Foo.java, use this code:

URL path = Foo.class.getResource("myFile.txt");
File f = new File(path.getFile());
reader = new BufferedReader(new FileReader(f));

Authorship

Can't access the file. Giving NullPointerException in path.getFile. – Besant

This worked for me thanks. I suggest you write the first code like this: URL path = JAVA_FILE_NAME.class.getResource("myFile.txt"); – Keyway

Answer 4

Files in your project are available to you relative to your src folder. if you know which package or folder myfile.txt will be in, say it is in

----src
--------package1
------------myfile.txt
------------Prog.java

you can specify its path as "src/package1/myfile.txt" from Prog.java

Sparke

Answer 5

Thanks @Laurence Gonsalves your answer helped me a lot. your current directory will working directory of proccess so you have to give full path start from your src directory like mentioned below:

public class Run {
public static void main(String[] args) {
    File inputFile = new File("./src/main/java/input.txt");
    try {
        Scanner reader = new Scanner(inputFile);
        while (reader.hasNextLine()) {
            String data = reader.nextLine();
            System.out.println(data);
            
        }
        reader.close();
    } catch (FileNotFoundException e) {
        System.out.println("scanner error");
        e.printStackTrace();
    }
}

}

While my input.txt file is in same directory.

Genro

Answer 6

If you know your file will live where your classes are, that directory will be on your classpath. In that case, you can be sure that this solution will solve your problem:

URL path = ClassLoader.getSystemResource("myFile.txt");
if(path==null) {
     //The file was not found, insert error handling here
}
File f = new File(path.toURI());

reader = new BufferedReader(new FileReader(f));

Sponsor

Answer 7

Try this:

BufferedReader br = new BufferedReader(new FileReader("java_module_name/src/file_name.txt"));

Footmark

Answer 8

try using "." E.g.

File currentDirectory = new File(".");

This worked for me

Thermoelectricity