Question

I have a very odd problem.

A class property is mysteriously reset between method calls.

The following code is executed so the constructor is called, then the parseConfiguration method is called. Finally, processData is called.

The parseConfiguration method sets the “recursive” property to “true”. However, as soon as it enters “processData”, “recursive” becomes “false”.

This problem isn’t isolated to a single class — I have several examples of this in my code.

How can this possibly be happening? I’ve tried initialising properties when they’re declared outside any methods, I’ve tried initialising them in constructors… nothing works.

The only complication I can think of here is that this class is invoked by an object that runs in a thread — but here is one instance per thread, so surely no chance that threads are interfering. I’ve tried setting both methods to “synchronized”, but this still happens.

I’m on JDK 1.6.0_19 on linux.

Please help!

/**
 * This class or its superclasses are NOT threaded and don't extend Thread
 */
public class DirectoryAcquirer extends Manipulator
{
/**
 * @var Whether to recursively scan directories
 */
private boolean recursive = false;

/**
 * Constructor
 */
public DirectoryAcquirer()
{
}

/**
 * Constructor that initialises the configuration
 *
 * @param config
 * @throws InvalidConfigurationException
 */
public DirectoryAcquirer(HierarchicalConfiguration config) throws InvalidConfigurationException
{
    super(config);
}

@Override
protected void parseConfiguration() throws InvalidConfigurationException
{
    // set whether to recurse into directories or not
    if (this.config.containsKey("recursive"))
    {
    // this.recursive gets set to "true" here
        this.recursive = this.config.getBoolean("recursive");

    }
}

@Override
public EntityCollection processData(EntityCollection data)
{
// here this.recursive is "false"
    this.logger.debug("processData: Entered method");
}
}

Answer 1

Thanks for your replies.

It seems that the problem was related to casting:

/**
 * 
 */
public class Manipulator
{
    // both constructors call parseConfiguration()

    protected void parseConfiguration() throws InvalidConfigurationException
    {
      // don't do anything. this is a default method that can optionally be 
      // overridden by subclasses
    }
}

I was referring in some places to the object as a DirectoryAcquirer, an at other times it was upcast to a Manipulator. I think that this was interfering so the empty parseConfiguration method was called after the child one was called — or something like that.

Anyway, I made the parseConfiguration method in the superclass abstract, and now it’s fine.