How do I load a file from resource folder?

My project has the following structure:

/src/main/java/
/src/main/resources/
/src/test/java/
/src/test/resources/

I have a file in /src/test/resources/test.csv and I want to load the file from a unit test in /src/test/java/MyTest.java

I have this code which didn't work. It complains "No such file or directory".

BufferedReader br = new BufferedReader (new FileReader(test.csv))

I also tried this

InputStream is = (InputStream) MyTest.class.getResourcesAsStream(test.csv))

This also doesn't work. It returns null. I am using Maven to build my project.

Solution 1:

Try the next:

ClassLoader classloader = Thread.currentThread().getContextClassLoader();
InputStream is = classloader.getResourceAsStream("test.csv");

If the above doesn't work, various projects have been added the following class: ClassLoaderUtil¹ (code here).²

Here are some examples of how that class is used:

src\main\java\com\company\test\YourCallingClass.java
src\main\java\com\opensymphony\xwork2\util\ClassLoaderUtil.java
src\main\resources\test.csv

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

// 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
}

Notes

1. See it in The Wayback Machine.
2. Also in GitHub.

Solution 2:

Try:

InputStream is = MyTest.class.getResourceAsStream("/test.csv");

IIRC getResourceAsStream() by default is relative to the class's package.

As @Terran noted, don't forget to add the / at the starting of the filename

Solution 3:

Try Flowing codes on Spring project

ClassPathResource resource = new ClassPathResource("fileName");
InputStream inputStream = resource.getInputStream();

Or on non spring project

 ClassLoader classLoader = getClass().getClassLoader();
 File file = new File(classLoader.getResource("fileName").getFile());
 InputStream inputStream = new FileInputStream(file);

Solution 4:

Here is one quick solution with the use of Guava:

import com.google.common.base.Charsets;
import com.google.common.io.Resources;

public String readResource(final String fileName, Charset charset) throws IOException {
        return Resources.toString(Resources.getResource(fileName), charset);
}

Usage:

String fixture = this.readResource("filename.txt", Charsets.UTF_8)