Question

I have a service interface that reads thus

package services;

import domain.Items;

public interface IItemsService extends IService {

public final String NAME = "IItemsService";


/** Places items into the database */
public void storeItem(Items items);




/** Retrieves items from the database
 * 
 * @param category
 * @param amount
 * @param color
 * @param type
 * @return
 * @throws ClassNotFoundException 
 */
public Items getItems (String category, float amount, String color, String type) throws ItemNotFoundException, ClassNotFoundException;

}

And a factory that looks like this…

package services;
public class Factory {



public Factory(){}



@SuppressWarnings("unchecked")
public IService getService(String name) throws ServiceLoadException {
    try {
        Class c = Class.forName(getImplName(serviceName));
        return (IService)c.newInstance();
    } catch (Exception e) {
        throw new ServiceLoadException(serviceName + "not loaded");
    }
}



private String getImplName (String name) throws Exception {
    java.util.Properties props = new java.util.Properties();
        java.io.FileInputStream fis = new java.io.FileInputStream("properties.txt");
            props.load(fis);
                fis.close();
                return props.getProperty(serviceName);
}
}

This should be really simple – but I keep getting two errors – IService cannot be resolved to a type (on both the factory and the service) and also an serviceName cannot be resolved into a variable error in the factory. I know I am missing something simple…

Answer 1

Regarding the type error: if IService is not in the package services, then IItemService will not have access to it and you will need to import some.package.name.IService.

The second answer is simple: in the getService and getImplName methods, the parameter is named name. In the method bodies, you’re referring to it as serviceName. You should probably change name to serviceName in each of them.

If, on the other hand, you’re trying to access an instance variable, note that in Java you have to declare all instance variables before you can access (read from/write to) them. You would need to modify the class as such:

public class Factory {

    private String serviceName;

    public Factory () {}

    // other code
}