Question

So, I’m trying out the apache log4j library and I managed to get everything working correctly. I ran my program once and it did all of the logging just perfectly. Then, I went to run it again and it crashed. I tried again and again the program crashed.

I have a few .properties files in a properties/ directory. I’m using two different .properties files and loading them both using getResource and getResourceAsStream respectively:

first in order to configure my logger:

PropertyConfigurator.configure(MyClass.class.getResource("properties/MyClassconfig.properties"));

then in order to load all of the constants used in the program:

properties.load(MyClass.class.getResourceAsStream("properties/constants.properties"));

As I said before, on the first run this worked perfectly. From the second run, I got this error:

log4j:ERROR Could not read configuration file from URL [null].
java.lang.NullPointerException
    at org.apache.log4j.PropertyConfigurator.doConfigure(PropertyConfigurator.java:522)
    at org.apache.log4j.PropertyConfigurator.configure(PropertyConfigurator.java:415)
    at com.package.package2.common.main.MyClass.main(MyClass.java:69)
log4j:ERROR Ignoring configuration file [null].

So, the line:

MyClass.class.getResource("properties/MyClassconfig.properties")

is no longer returning a valid URL, but instead it’s returning null. I was thinking this was because some InputStream remained open after the first run (like the input stream opened in:

MyClass.class.getResource("properties/MyClassconfig.properties"); )

The reason I think there is a conflict between getResource and getResourceAsStream is because the crash actually happens later when I call:

properties.load(MyClass.class.getResourceAsStream("properties/constants.properties"));

I get:

Properties$LineReader.readLine() line: not available [local variables unavailable]  
Properties.load0(Properties$LineReader) line: not available 
Properties.load(InputStream) line: not available    

Even though there is no link between the logger itself and the Properties.load() and its InputStream (other than that they are both initialized with .properties files)

Answer 1

Why not just have log4j.properties in your classpath and do away with all the manual resource loading?