Class.getResourceAsStream() VS. ClassLoader.getResourceAsStream()

lass.getResource

 can
take a "relative" resource name, which is treated relative to the class's package. Alternatively you can specify an "absolute" resource name by using a leading slash. Classloader resource paths are always deemed to be absolute.

So they are basically equivalent:

foo.bar.Baz.class.getResource("xyz.txt");
foo.bar.Baz.class.getClassLoader().getResource("foo/bar/xyz.txt");

And so are these (but they're different to the above :)

foo.bar.Baz.class.getResource("/data/xyz.txt");
foo.bar.Baz.class.getClassLoader().getResource("data/xyz.txt");

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getResourceAsStream in static method

Non Static Method

URL url = getClass().getResource("ListStopWords.txt");
File file = new File(url.getPath());

InputStream inputStream =
getClass().getClassLoader().getResourceAsStream("config.properties");

2. Static Method

InputStream inputStream =
FileHelper.class.getClassLoader().getResourceAsStream("config.properties");

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For Class.getResourceAsStream(String name), if the name parameter doesn't start with a "/", then it's a relative path to the
class's package. If the name parameter starts with a "/", then it's an absolute path.

For ClassLoader.getResourceAsStream(String name), the name parameter is always an absolute path, and it can never start with a "/".
If it does, the resource is never found.

If the file cannot be found, both methods return null and no exception is thrown.

The following program illustrates the difference.

Project structure





ResourceAsStream.java 

public class ResourceAsStream {

    /**
     * @param args
     */
    public static void main(String[] args) {
        String path1 = "a.properties";
        String path2 = "/a.properties";
        String path3 = "test/a.properties";
        String path4 = "/test/a.properties";

        System.out.println("Class.getResourceAsStream()");
        InputStream is = ResourceAsStream.class.getResourceAsStream(path1);
        System.out.println(path1 + " " + (is != null));
        is = ResourceAsStream.class.getResourceAsStream(path2);
        System.out.println(path2 + " " + (is != null));
        is = ResourceAsStream.class.getResourceAsStream(path3);
        System.out.println(path3 + " " + (is != null));
        is = ResourceAsStream.class.getResourceAsStream(path4);
        System.out.println(path4 + " " + (is != null));
        System.out.println();
        System.out.println("ClassLoader.getResourceAsStream()");
        is = ResourceAsStream.class.getClassLoader().getResourceAsStream(path1);
        System.out.println(path1 + " " + (is != null));
        is = ResourceAsStream.class.getClassLoader().getResourceAsStream(path2);
        System.out.println(path2 + " " + (is != null));
        is = ResourceAsStream.class.getClassLoader().getResourceAsStream(path3);
        System.out.println(path3 + " " + (is != null));
        is = ResourceAsStream.class.getClassLoader().getResourceAsStream(path4);
        System.out.println(path4 + " " + (is != null));

    }

}

Result: 

Class.getResourceAsStream()
a.properties true
/a.properties false
test/a.properties false
/test/a.properties true

ClassLoader.getResourceAsStream()
a.properties false
/a.properties false
test/a.properties true

/test/a.properties false