Question

执行我的Android应用程序时出现此错误：

 FATAL EXCEPTION: AsyncTask #1
 java.lang.RuntimeException: An error occured while executing doInBackground()

at android.os.AsyncTask$3.done(AsyncTask.java:299)
at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
at java.util.concurrent.FutureTask.run(FutureTask.java:137)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
at java.lang.Thread.run(Thread.java:856)
  Caused by: java.lang.NoClassDefFoundError: com.hp.hpl.jena.query.Syntax
at com.example.testtvprg.QueryDBpedia.doInBackground(QueryDBpedia.java:56)
at com.example.testtvprg.QueryDBpedia.doInBackground(QueryDBpedia.java:1)
at android.os.AsyncTask$2.call(AsyncTask.java:287)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)

这是我的AsyncTask类：我尝试连接到DBpedia并使用Jena Api发送查询，然后我在My MainActivity类上调用此类：

import java.util.ArrayList;
import android.os.AsyncTask;
import android.util.Log;
import com.hp.hpl.jena.query.Query;
import com.hp.hpl.jena.query.QueryExecution;
import com.hp.hpl.jena.query.QueryExecutionFactory;
import com.hp.hpl.jena.query.QueryFactory;
import com.hp.hpl.jena.query.ResultSet;
import com.hp.hpl.jena.query.ResultSetFactory;
import com.hp.hpl.jena.query.ResultSetFormatter;
import com.hp.hpl.jena.query.Syntax;
import com.hp.hpl.jena.rdf.model.RDFNode;


 public class QueryDBpedia extends AsyncTask <String, Void, Void>{ArrayList<String> list= new ArrayList<String>();
@Override
protected Void doInBackground(String... keyword) {
    try{
            String sparqlQuery="PREFIX rdf:<http://www.w3.org/1999/02/22-rdf-syntax-ns#>\n" + 
        "SELECT DISTINCT ?film_URI \n" +
        "WHERE {\n" +
        "?film_URI rdf:type <http://dbpedia.org/ontology/Film> . \n" +
        "} Limit 10" ;
    String service=  "http://dbpedia.org/sparql";
    Query qur=QueryFactory.create(sparqlQuery,Syntax.syntaxARQ);
    QueryExecution exec = QueryExecutionFactory.sparqlService(service,qur );
    ResultSet results = ResultSetFactory.copyResults( exec.execSelect() );

    while ( results.hasNext() ) {
         RDFNode s= results.next().get( "resource" );
         list.add(s.toString());
                }

    }  catch (Exception  e) {
        Log.e("Jena", "Error parsing data " + e.toString());
    }
    return null;
} }

以及我调用asyncTask类的函数下面：

public void ExplorButton( View v) throws InterruptedException, ExecutionException, IOException 
    {   
        QueryDBpedia qdb=   new  QueryDBpedia();
        qdb.execute("");

    }

我不明白问题出在哪里。请帮帮我。

Answer 1

您的包中缺少

com.hp.hpl.jena.query.Syntax ，请尝试发布代码。

NoClassDefFoundError问题

1 个答案: