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Thread: How can I check to see if a file ending with a certain extension exists in the current working directory

  1. #1
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    Default How can I check to see if a file ending with a certain extension exists in the current working directory

    This question is different from "Find files in a folder using Java" that has already been asked because I do not know what the users current working directory will be. I need my program to look in the current working directory that the program is running from, to look for a certain file.

    I need to have my program check to see if a file ending with ".lic" exist in the current working directory before it executes. If the file does not exist, I need a message to appear alerting the user that they need to activate the license. Here is the code that I have.

    When I run it through the debug, "user.dir" give a message - user.dir = >Unknown type "user.dir"<

    String License says "License = >"License" is not a known variable in the current context.<"

    try{
     
        String License = System.getProperty("user.dir") + ("*.lic");
        File license = new File(License);
          if (license.exists()){
        try{
        Runtime.getRuntime().exec(cmd);
     
        } catch (IOException ex) {
      }
          } else {
              JOptionPane.showMessageDialog(null, "Need to activate license, please see README file");
          }
      }catch(HeadlessException e){
          // if any error occurs
     
      }
     
     
    }

  2. #2
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    Default Re: How can I check to see if a file ending with a certain extension exists in the current working directory

    // if any error occurs
    Make sure that all catch blocks have a call to the printStackTrace method so you will get a message if there is an error.

    What happens when the posted code is compiled and executed? What do you want to be different?

    How are you trying to debug the code? What is the value of License? Print it to see.


    String License = System.getProperty("user.dir") + ("*.lic");
    Note: * is not a valid character for a filename
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: How can I check to see if a file ending with a certain extension exists in the current working directory

    It is not getting the current working directory. I need to look for a file ending in ".lic".
    When I try to get the value of License, this is what it says, "License = >"License" is not a known variable in the current context.<"

  4. #4
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    Default Re: How can I check to see if a file ending with a certain extension exists in the current working directory

    I need to look for a file ending in ".lic".
    Do you know the name of the file? Why not use that name in filename String passed to the File class's constructor?

    When I try to get the value of License
    What code are you using to do that? Can you post that code?

    it says, "License = >"License" is not a known variable in the current context.<"
    What program is the it you talk about?

    It is not getting the current working directory.
    How do you know that? What value is it getting for the current working directory?
    What is the correct value?

    look for a file ending in ".lic".
    One way to see all the files with that extension is to Use the File class's list method with a filename filter.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: How can I check to see if a file ending with a certain extension exists in the current working directory

    My program needs to check for any files ending .lic. If there is a file ending in ".lic" then run the user input. If a ".lic" does not exist then pop up a message.
    in my code the "user.dir" is not getting the current working directory.
    License value is - "License" is not a known variable in the current context.<"

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    Default Re: How can I check to see if a file ending with a certain extension exists in the current working directory

    the "user.dir" is not getting the current working directory.
    Please post the value returned by System.getProperty("user.dir")
    and also post what you think is the current working directory

    License value is - "License" is not a known variable in the current context.<"
    Where does that message come from? Can you post the code that causes that message?

    check for any files ending .lic.
    Please read what I have posted:
    One way to see all the files with that extension is to Use the File class's list method with a filename filter.
    If you don't understand my answer, don't ignore it, ask a question.

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