Question

I am trying to load a class whose name is specified in a properties file. Here is the code for the same.

try {
    Properties properties = new Properties();   
    InputStream in = MyAbstractFactory.class.getResourceAsStream("/some.properties");
    properties.load(in);
    String impl = properties.getProperty("key");
    MyAbstractFactory factories = (MyAbstractFactory) Class.forName( impl ).newInstance();
    return factories;
} catch (Exception e) {
    return new DefaultFactoriesImpl();
}

This code is part of a jar file. the properties file is just outside the jar. Its unable to load the properties file and is loading DefaultFactoriesImpl instead. I know this happens when MyAbstractFactory.class.getResourceAsStream cant find the resource in the class path but that doesn’t seem to be the case here.

Dir Structure:-

• com
• myjar.jar
• some.properties

Command i am executing is “java -jar myjar.jar”

Any feedback on why this might be happening. Could this have something to do with Clasloaders? I’d like to add that when i run this code from within eclipse it seems pick up some.properties just fine.

Answer 1

Remove the leading slash from the argument you pass to getResourceAsStream().

Put the folder outside the JAR into the CLASSPATH when you execute the JAR. I don’t know if the manifest CLASSPATH overrides the one you might pass using -cp. Play with it; one of them will work.

It’s not finding your .properties file because it’s not in the JVM CLASSPATH. When you do it properly, the JVM will find it.