How to get to a file by passing relative path in java?

Question

I am trying to understand "How to get to file by passing relative path of a file or folder?" . Here is the example:

CODE:

  public class somex {
    public static void main {
       String fileName = System.getProperty("user.dir");   <---This gives me path for the current working directory.
       File file = new File(fileName + "../../xml_tutorial/sample.xlsx" );
       System.out.println(file.getCanonicalPath());         <---This gives me path for the file that is residing in folder called "xml_tutorial".
     }
  }

    >>>>

Here, I know the file location so i was able to pass correct relative path. And, managed to print the file path. I have deleted the "sample.xlsx" and executed the above code; With no failing it gives me the path name and it is same path as when the file exists (i.e. before deleting). How it is possible ? I am expecting EXCEPTION here. why it is not throwing exception ?

Two, I want to use regular expression for the file name, such as: "../../xml_tutorial/samp.*". But this doesn't do the job and it gives me IOException. Why it is not able to identify the file sample.xlsx ? (NOTE: this is when the file exist and one hundred precent sure there is only one file with the name "sample.xlsx")

1. you can check the file with file.exists() method. 2. java not support wildcard, you can find answer here http://stackoverflow.com/questions/794381/how-to-find-files-that-match-a-wildcard-string-in-java — Terry Ma, May 04 '13 at 14:05

T.J. Crowder · Accepted Answer · 2013-05-04T14:11:58.443

I have deleted the "sample.xlsx" and executed the above code; With no failing it gives me the path name and it is same path as when the file exists (i.e. before deleting). How it is possible ? I am expecting EXCEPTION here. why it is not throwing exception ?

File doesn't care whether the file actually exists. It just resolves the path. There's no need for the file to exist in order to take the path

/home/tjc/a/b/c/../../file.txt

...and turn it into the canonical form

/home/tjc/a/file.txt

If you want to know whether the file on that path actually exists, you can use the exists() method.

On your second, unrelated question:

Two, I want to use regular expression for the file name, such as: "../../xml_tutorial/samp.*". But this doesn't do the job and it gives me IOException. Why it is not able to identify the file sample.xlsx ?

There's nothing in the File documentation saying that it supports wildcards. If you want to do searches, you'll want to use list(FilenameFilter) or listFiles(FilenameFilter) and a FilenameFilter implementation, or listFiles(FileFilter) and a FileFilter implementation.

How to get to a file by passing relative path in java?

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