Java file path f.exists() always returns false

I'm trying to create a basic Java program that allows the user create files and folders.

I want all this to happen in a folder inside my project (image attached) so I've got some doubts...

Is the folder "Test" correctly placed? if not how do i access to it? As you see, it's inside com.company, should I move it to src?
When I try to check if exists, it says false.

This is my code:

public class Main {
    Scanner input = new Scanner(System.in);

    public static void main(String[] args) {
        Main main = new Main();
        main.init();
    }

    public void init(){
        File f = new File("Test"); //Here i've tried "com"+File.separator+"company"+File.separator+"Test"
        System.out.println(f.exists()); //output is false here

    }
}

f.getParent() says null.

But when I try: System.out.println(f.getAbsolutePath()); it shows correctly the whole path.

The point of using relative path is because i'd like this code to work on ANY computer.

Thanks in advice, hope someone could help me a bit.

Solution

If you use relative pathnames in Java, they will be resolved relative to the running application's working directory. So you need to know what the working directory is going to be.

When you are launching an application in an IDE, the working directory depends on the IDE and the launcher configs. But it is typically the file system directory that corresponds to the top of the project.

Another thing to note is that the src folder you see is special. The entries in it are typically not files and directories. The are typically Java packages and classes. So in the file system, "src" > "com.company" > "Main" is actually represented as a file with the path "src/com/company/Main.java".

This means that it is kind of wrong to put arbitrary folders and files into the "src" folder. It will work ... but it is conceptually wrong. Data files don't belong in the source tree, and certainly not data files written by your application. (And when you start using a source control system, you will find that writing data files into your source tree is going to give you a headache. I won't go into details ... but I am pretty sure that you would regret it.)

The other thing that is conceptually wrong about what you are doing is that Java programs are normally written to be free standing things. The user of your program should not need to download and install Intellij or some other IDE and load your project into it. They will want to just run it from a JAR file. In that world, the project directory and the "src" folder won't exist, and hardwiring relative paths like "src/Test" will be problematic.

So lets ignore that for now and look at what your code is currently doing

Is the folder "Test" correctly placed? if not how do i access to it? As you see, it's inside com.company, should I move it to src?

According to the image, the Test folder (actually package) >>is<< in the src Folder.

When I try to check if exists, it says false.

Your code is using the wrong path. With the "Test" folder places where you have it (according to the picture!), the relative path should be "src/Test", not "Test" or "com/company/Test".

Note that Windows accepts either "/" or "\" will work as a file separator, even though "\" is what is used conventionally.

f.getParent() says null.

That is correct. The relative path "Test" does not have a parent part. It is a simple file / directory name.

Think of it this way. Until a File with a relative path is resolved, it is not determined what directory it is relative to.

But when I try: System.out.println(f.getAbsolutePath()); it shows correctly the whole path.

Again, correct.

When you call f.getAbsolutePath() on a relative File, the runtime system prepends the path of the application's working directory, and then gives you the result.

The point of using relative path is because I'd like this code to work on ANY computer.

That relative path will NOT work on ANY computer. You are using a path that is within your project's src tree, and your project typically won't exist on an end-user's computer. (See above.)

So what should you do?

There is no single correct answer.

You could put the file / directory into the user's current / working directory.
You could put the file / directory into the user's home directory, or a hidden subdirectory in the home directory. (This is a common approach on Linux.)
You could make the pathname for the directory a command line argument
You could get the pathname from an environment variable
You could get the pathname from an application specific config file.

The best answer will depend on the context.