public ValueStackDataSource(ValueStack valueStack,
    String dataSource) 
{
        this.valueStack = valueStack;
        Object dataSourceValue = valueStack.findValue(dataSource);
        if (dataSourceValue != null) {
            if (MakeIterator.isIterable(dataSourceValue)) {
                iterator = MakeIterator.convert(dataSourceValue);
            } else {
                Object[] array = new Object[1];
                array[0] = dataSourceValue;
                iterator = MakeIterator.convert(array);
            }
        } else {
            LOG.warn("Data source value for data source " + dataSource + " was null");
        }
}

Create a value stack data source on the given iterable property

Parameters:

valueStack - The value stack to base the data source on

dataSource - The property to iterate over for the report

 public Object getFieldValue(JRField field) throws JRException 
{
        //TODO: move the code to return a ValueStackDataSource to a seperate
        //      method when and if the JRDataSource interface is updated to support
        //      this.
        String expression = field.getDescription();
        if (expression == null) {
            //Description is optional so use the field name as a default
            expression = field.getName();
        }
        Object value = valueStack.findValue(expression);
        if (LOG.isDebugEnabled()) {
            LOG.debug("field: " + field.getName() + "/" + value);
        }
        if (MakeIterator.isIterable(value)) {
            //                return new ValueStackDataSource(this.valueStack, field.getName());
            return new ValueStackDataSource(this.valueStack, expression);
        } else {
            return value;
        }
}

Get the value of a given field

 public boolean next() throws JRException 
{
        if (firstTimeThrough) {
            firstTimeThrough = false;
        } else {
            valueStack.pop();
        }
        if ((iterator != null) && (iterator.hasNext())) {
            valueStack.push(iterator.next());
            LOG.debug("Pushed next value: " + valueStack.findValue("."));
            return true;
        } else {
            LOG.debug("No more values");
            return false;
        }
}

Is there any more data