Where to put a textfile I want to use in eclipse?

Question

hi there,

I need to read a text file when I start my program. I'm using eclipse and started a new java project. In my project folder I got the "src" folder and the standard "JRE System Library" + staedteliste.txt... I just don't know where to put the text file. I literally tried every folder I could think off....I cannot use a "hard coded" path because the text file needs to be included with my app...

I use the following code to read the file, but I get this error:

Error:java.io.FileNotFoundException:staedteliste.txt(No such file or directory)

---

public class Test {

ArrayList<String[]> values;

public static void main(String[] args) {
    // TODO Auto-generated method stub

    URL url = Test.class.getClassLoader().getResource("src/mjb/staedteliste.txt");
    System.out.println(url.getPath()); // I get a nullpointerexception here!
    loadList();
}

public static void loadList() {
    BufferedReader reader;
    String zeile = null;

    try {
        reader = new BufferedReader(new FileReader("src/mjb/staedteliste.txt"));
        zeile = reader.readLine();          

        ArrayList<String[]> values = new ArrayList<String[]>();

        while (zeile != null) {             
            values.add(zeile.split(";"));
            zeile = reader.readLine();
        }
        System.out.println(values.size());
        System.out.println(zeile);

    } catch (IOException e) {
        System.err.println("Error :"+e);
    }
}

}

Answer 1

Depending on your Java class package name, you're probably 4 or 5 levels down the directory structure.

If your Java class package is, for example, com.stackoverflow.project, then your class is located at src/com/stackoverflow/project.

You can either move up the directory structure with multiple ../, or you can move the text file to the same package as your class. It would be easier to move the text file.

Answer 2

One path to take is to

1. Add the file you're working with to the classpath

2. Use the resource loader to locate the file:

       URL url = Test.class.getClassLoader().getResource("myfile.txt");
       System.out.println(url.getPath());
       ...
   

3. Open it

Answer 3

You should probably take a look at the various flavours of getResource in the ClassLoader class: http://java.sun.com/j2se/1.4.2/docs/api/java/lang/ClassLoader.html

Answer 4

Ask first yourself: if your file supposed to be an internal component of you application? (that usually means it is to be packed inside you jar, or war if a web-app; typically some configuration file or static resource, read-only).

If the answer is yes, you don't want to specify an absolute path for the file. But you neither want to access it with a relative path (as your example), because Java assumes that path is relative to the "current directory" and that is not the most useful notion, typically.

Usually the prefered option for this scenario is to load it relatively from the classpath.

Java provides you the getResource() method for doing this. And Eclipse (in the normal setup) assumes src/ is to be in the root of your classpath, so that, after compiling, it copies everything to your output directory ( bin/ ), the java files in compiled form ( .class ), the rest as is.

So, for example, if you place your file in src/Files/myfile.txt, it will be copied at compile time to bin/Files/myfile.txt ; and, at runtime, bin/ will be in (the root of) your classpath. So, by calling getResource("/Files/myfile.txt") (in some of its variants) you will be able to read it.

Edited: Further, if your file is conceptually tied to a java class (eg, some com.example.MyClass has a MyClass.cfg associated configuration file), you can use the getResource() method from the class and use a (resource) relative path: MyClass.getResource("MyClass.cfg"). The file then will be searched in the classpath, but with the class package pre-appended. So that, in this scenario, you'll typically place your MyClass.cfg and MyClass.java files in the same directory.

Answer 5

Suppose you have a project called "TestProject" on Eclipse and your workspace folder is located at E:/eclipse/workspace. When you build an Eclipse project, your classpath is then e:/eclipse/workspace/TestProject. When you try to read "staedteliste.txt", you're trying to access the file at e:/eclipse/workspace/TestProject/staedteliste.txt.

If you want to have a separate folder for your project, then create the Files folder under TestProject and then access the file with (the relative path) /Files/staedteliste.txt. If you put the file under the src folder, then you have to access it using /src/staedteliste.txt. A Files folder inside the src folder would be /src/Files/staedteliste.txt

Instead of using the the relative path you can use the absolute one by adding e:/eclipse/workspace/ at the beginning, but using the relative path is better because you can move the project without worrying about refactoring as long as the project folder structure is the same.