Why do I get a NullPointerException when initializing Spring

Question

Hi guys,

I've got a problem running a batch job on my server, whereas it runs fine from Eclipse on my development workstation.

I've got my Spring environment set up using Roo, made an entity, and make a batch that does some work, and test it well on my develompent box. I initialize my context and do the work, but when I run my batch on the server, the context isn't initialized properly. Here's the code:

public class TestBatch {

    private static ApplicationContext context;


    @SuppressWarnings("unchecked")
    public static void main(final String[] args) {

            context = new ClassPathXmlApplicationContext("/META-INF/spring/applicationContext.xml");
            try {
                @SuppressWarnings("unused")
                TestBatch app = new TestBatch();
            } catch (Exception ex) {
                ex.printStackTrace();
            }
    }

    public void TestBatch() { /** Do Something using the context **/ }

}

And here's the log and exception:

2010-02-16 11:54:16,072 [main] INFO  org.springframework.context.support.ClassPathXmlApplicationContext - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@6037fb1e: startup date [Tue Feb 16 11:54:16 CET 2010]; root of context hierarchy
Exception in thread "main" java.lang.ExceptionInInitializerError
    at org.springframework.context.support.AbstractRefreshableApplicationContext.createBeanFactory(AbstractRefreshableApplicationContext.java:194)
    at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:127)
    at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:458)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:388)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
    at tld.mydomain.myproject.batch.TestBatch.main(TestBatch.java:51)
Caused by: java.lang.NullPointerException
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.<clinit>(DefaultListableBeanFactory.java:103)
    ... 7 more

Any idea or hints as to what's going on? My classpath is set to $PROJECTHOME/target/classes, and all my dependencies are in $PROJECTHOME/target/lib, and I execute using "export CLASSPATH=$PROJECTHOME/target/classes; java -Djava.endorsed.dirs=$PROJECTHOME/target/lib tld.mydomain.myproject.batch.TestBatch"

Is there anything in my setup that looks very wrong? When I run this from Eclipse, no problems, but when I deploy it on the server where I want to run it and run it as described above, I get this problem. Because it runs from Eclipse, I believe my config files are all right, but how can I debug what's causing this? Perhaps I have some config errors or a mismatch between the server and the development workstation after all? Or is this a really weird way of saying file not found, and if so, how do I make sure it finds the correct file??

I'm really looking forward to hearing your suggestions as to how to tackle this problem.

Cheers

Nik

Answer 1

The cause of problem is -Djava.endorsed.dirs=$PROJECTHOME/target/lib org.springframework.beans.factory.support.DefaultListableBeanFactory contains the following code:

static {
    ClassLoader cl = DefaultListableBeanFactory.class.getClassLoader();
    try {
        javaxInjectProviderClass = cl.loadClass("javax.inject.Provider"); //Line 103
    }
    catch (ClassNotFoundException ex) {
        // JSR-330 API not available - Provider interface simply not supported then.
    }
}

It causes a NullPointerException, because getClassLoader() returns null when class is loaded via -Djava.endorsed.dirs. From javadoc:

Some implementations may use null to represent the bootstrap class loader.

So, use -classpath (with explicit specification of all jars) instead of -Djava.endorsed.dirs