java.io.FileNotFoundException while running java app from jar file

Question

Hi i am running java app from jar file. like following java -cp test.jar com.test.TestMain . in the java app i am reading csv file. which is throwing below exception.

java.io.FileNotFoundException: file:\C:\Users\harinath.BBI0\Desktop\test.jar!\us_postal_codes.csv (The filename, directory name, or volume label syntax is incorrect)
        at java.io.FileInputStream.open(Native Method)
        at java.io.FileInputStream.<init>(FileInputStream.java:146)
        at java.util.Scanner.<init>(Scanner.java:656)
        at com.test.TestMain.run(TestMain.java:63)
        at com.test.TestMain.main(TestMain.java:43)

*csv file is located in src/main/resources folder.

code causes to exception is

public static void main(String[] args) throws Exception {
    TestMain trainerScraper = new TestMain();
    trainerScraper.run();
}

private void run() throws JsonParseException, JsonMappingException, IOException{
    String line = "";
    String cvsSplitBy = ",";

    //Get file from resources folder
    ClassLoader classLoader = getClass().getClassLoader();
    System.out.println(csvFile);
    URL url = classLoader.getResource("us_postal_codes.csv");
    String fileName = url.getFile();
    File file = new File(fileName);

    try (Scanner scanner = new Scanner(file)) {
        line = scanner.nextLine();          //header
        while ((scanner.hasNextLine())) {

thanks.

Also what are these two lines `at com.test.TestMain.run(TestMain.java:63) at com.test.TestMain.main(TestMain.java:43)` in your class? — Naman, May 17 '16 at 07:47
1. would suggest using `System.getProperty("user.dir")` to find the current working directory — Naman, May 17 '16 at 07:53
as @Sanjeev says, you have to add resources's directory to your classpath. — Asma, May 17 '16 at 07:54
@Sanjeev, how can i add the resources's directory to your classpath. can u please brief it. — Harinath, May 17 '16 at 08:05

Naman · Answer 1 · 2016-05-17T08:15:51.410

3

test.jar!\us_postal_codes.csv (The filename, directory name, or volume label syntax is incorrect)

Would suggest using

System.getProperty("user.dir") // to get the current directory, if the resource is in the project folder

and

getResourceAsStream("/us_postal_codes.csv") // if its inside a jar

edited May 17 '16 at 08:15

answered May 17 '16 at 08:01

Naman

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thanks its working. small change getResourceAsStream("/us_postal_codes.csv") – Harinath May 17 '16 at 08:11
@Harinath : my bad, improved – Naman May 17 '16 at 08:16
@Harinath : if this solves your problem, could you please select it as the answer – Naman Jun 06 '16 at 05:02

Tamas Rev · Answer 2 · 2016-05-17T08:12:53.667

2

Based on the stack trace below we can see that the Scanner cannot find the file:

at java.util.Scanner.<init>(Scanner.java:656)
at com.test.TestMain.run(TestMain.java:63)

By the way, where is the file? If it's in the jar, then you can use TestMain.class.getResourceAsStream() - Scanner has an InputStream constructor too:

InputStream iStream = TestMain.class.getResourceAsStream("/us_postal_codes.csv"); // this supposes the csv is in the root of the jar file
try (Scanner scanner = new Scanner(iStream)) {
    //...
}
//...

edited May 17 '16 at 08:12

answered May 17 '16 at 07:57

Tamas Rev

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csv file is in jar file. in the root. but still getting exection. `java.lang.NullPointerException at java.io.Reader.(Reader.java:78) at java.io.InputStreamReader.(InputStreamReader.java:72) at java.util.Scanner.(Scanner.java:608)` – Harinath May 17 '16 at 08:03
HI its working fine, i just put '/' to file name like this. "/us_postal_codes.csv". thanks @tamas rev – Harinath May 17 '16 at 08:09

score 1 · Answer 3 · answered May 17 '16 at 08:12

You should use getResourceAsStream. This is example:

public void test3Columns() throws IOException
{
  InputStream is = getClass().getResourceAsStream("3Columns.csv");
  InputStreamReader isr = new InputStreamReader(is);
  BufferedReader br = new BufferedReader(isr);
  String line;
  while ((line = br.readLine()) != null) 
  {
    CSVLineTokenizer tok = new CSVLineTokenizer(line);
    assertEquals("Should be three columns in each row",3,tok.countTokens());
  }
  br.close();
  isr.close();
  is.close();
}

ClassLoader.getResource method is not used to search files in .jar archives.

java.io.FileNotFoundException while running java app from jar file

3 Answers3