Read file from resource folder, InputStream is null [duplicate]

问题:

This question already has an answer here:

• How do I load a file from resource folder? 14 answers

Windows 7, x64, Java 11

How to read a file in resources folder in main.

    ClassLoader classloader = Thread.currentThread().getContextClassLoader();      // Input stream is null.     InputStream is = App.class.getResourceAsStream(filename);     BufferedReader br = new BufferedReader(new InputStreamReader(is));     return br.lines().collect(Collectors.toList()); 

I had a similar problem with test/resources.

private static List<String> readLines(final String filename) {     try (final InputStreamReader isr = new FileReader(getFileFromResource(filename));          final BufferedReader br = new BufferedReader(isr)) {         return br.lines().collect(Collectors.toList());     } catch (IOException e) {         throw new RuntimeException(String.format("Failed to read file: %s", filename), e);     } }  private static File getFileFromResource(final String filename) {      ///////// App.class.getResource is NULL      final URL url = App.class.getClassLoader().getResource(filename);     if (url == null) {         throw new RuntimeException(String.format("Failed to read resource %s from resources folder.", filename));     }     return new File(url.getFile()); } 

But what worked for test/resources does not work for java/resources.

What happened in Java-11 or in my code?

---

I tried this

URL url = ClassLoaderUtil.getResource("test.csv", YourCallingClass.class); Path path = Paths.get(url.toURI()); List<String> lines = Files.readAllLines(path, StandardCharsets.UTF_8); 

And this

// java.io.InputStream InputStream inputStream = ClassLoaderUtil.getResourceAsStream("test.csv", YourCallingClass.class); InputStreamReader streamReader = new InputStreamReader(inputStream, StandardCharsets.UTF_8); BufferedReader reader = new BufferedReader(streamReader);  for (String line; (line = reader.readLine()) != null;) {     // Process line } 

Other examples

And this does not help

 private List<String> readLines(String filename) {     // InputStream is null     InputStream is = getClass().getClassLoader()             .getResourceAsStream(filename);     BufferedReader br = new BufferedReader(new InputStreamReader(is));     return br.lines().collect(Collectors.toList()); } 

回答1:

I solved it!!!!

maven

I build my project with maven. After I added a file to resources, it did not go to target directory.

Rebuild the project.

mvn clean install 

文章来源: Read file from resource folder, InputStream is null [duplicate]