getResourceAsStream returns null

Question

I\'m loading a text file from within a package in a compiled JAR of my Java project. The relevant directory structure is as follows:

/src/initialization/Life         


        

Answer 1

The default JVM classloader will use parent-classloader to load resources first: .

Lifepaths.class.getClass()'s classloader is bootstrap classloader, so getResourceAsStream will search $JAVA_HOME only, regardless of user provided classpath. Obviously, Lifepaths.txt is not there.

Lifepaths.class 's classloader is system classpath classloader, so getResourceAsStream will search user-defined classpath and Lifepaths.txt is there.

When using java.lang.Class#getResourceAsStream(String name), name which is not start with '/' will be added with package name as prefix. If you want avoid this, please using java.lang.ClassLoader#getResourceAsStream. For example:

ClassLoader loader = Thread.currentThread().getContextClassLoader();
String resourceName = "Lifepaths.txt";
InputStream resourceStream = loader.getResourceAsStream(resourceName);