附加列表[數據庫]

我是新的Scala，我正在寫一個簡單的rss閱讀器。我有班級經理管理飼料和內容。附加列表[數據庫]

package lib 
import scala.xml._ 
import java.net.URL 
import net.liftweb.couchdb.{CouchDB, Database} 
import dispatch.{Http, StatusCode} 

/** 
* @author smix 
* 
* Feeds manager 
*/ 
object Manager { 
var db = List[Database]() 
/* 
    * Initialize CouchDb databases 
    */ 
def init = { 
    this.appendDb(new Database("myserver.com", 5984, "content")) 
} 

/* 
    * Append a new database to the databases list 
    */ 
private def appendDb(database: Database) : Unit = { 
    database :: db 
    // Strange exception if database has been already created 
    /* try { 
    this.db.head.createIfNotCreated(new Http()) 
    } catch { 
    case e:java.lang.NoClassDefFoundError => {} 
    } */ 
} 

/* 
    * Fetch articles from feed by url 
    */ 
    def fetchItems(feedUrl: String): List[scala.xml.Elem] = { 
    val rssFeed = XML.load((new URL(feedUrl)).openConnection.getInputStream) 
    val items = rssFeed \ "channel" \ "item" 

    val articles: List[scala.xml.Elem] = List() 
    for(item <- items) { 
     item :: articles 
    } 

    articles 
    } 

}

我想將內容存儲在CouchDb中。我需要有沙發數據庫列表（飼料，文章等）。我寫的類，但是當我打電話appendDb我得到一個錯誤：

Exception in thread "main" java.lang.NoClassDefFoundError: lib/Manager$ 
at collector$.main(collector.scala:5) 
at collector.main(collector.scala) 
Caused by: java.lang.ClassNotFoundException: lib.Manager$ 
at java.net.URLClassLoader$1.run(URLClassLoader.java:202) 
at java.security.AccessController.doPrivileged(Native Method) 
at java.net.URLClassLoader.findClass(URLClassLoader.java:190) 
at java.lang.ClassLoader.loadClass(ClassLoader.java:307) 
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) 
at java.lang.ClassLoader.loadClass(ClassLoader.java:248) 
... 2 more

當我rewrited db定義：var db = List[Int]()和appendDb的第一行：1 :: this.db項目運行良好......奇怪。

另外，有趣的是，爲什麼當我爲現有數據庫（appendDb中的註釋try-catch塊）調用createIfNotCreated時，我得到異常。

來源

2010-08-01 Andrey Kuznetsov