Parent Parent Directory in Java

Question

Please explain to me why when I run this code everything is fine and I get the parent directory of my classes:

URL dirUrl = PathsService.class.getResource(".."); 

and when I run this code:

 URL dirUrl = PathsService.class.getResource("../.."); 

I get null in dirUrl.

I try like this: URL dirUrl = PathsService.class.getResource("..//.."); anyway i have null in dirUrl.

How can I get the parent / parent / parent directory in Java?

Answer 1

NOTICE :

• As noted earlier, using any function when retrieving any parent directory is a very bad design idea (and one that almost certainly fails).
• If you provide more detailed information about what you are trying to achieve (the big picture), someone can probably offer a better solution.

However, you can try the following code:

 import java.nio.file.*; ... Path path = Paths.get(PathsService.class.getResource(".").toURI()); System.out.println(path.getParent()); // <-- Parent directory System.out.println(path.getParent().getParent()); // <-- Parent of parent directory 

Also note that the above technique may work in your development environment, but may (and probably will) produce unexpected results when your application is “correctly” deployed.

Answer 2

The result you get is absolutely right.

I think you misunderstood the use of class.getResource .

Suppose you have the package com.test and MyClass inside this package.

This MyClass.class.getResource(".") give you the location of the file you are executing from. Locates the MyClass .

This MyClass.class.getResource("..") move up 1 level in your package structure. Thus, this will return the location of the test directory.

This MyClass.class.getResource("../..") will go further 1 level up. Thus, this will return the location of the com directory.

Now this MyClass.class.getResource("../../..") will try to move up 1 level further, but since there is no package directory, this will return null .

So, class.getResource will not exit a specific package structure and begin accessing your computer directory. Here's how it doesn't work. This is done only in the structure of the current class .