nullpointerexception axis2 webservice

Question

I have a webservice on axis2, and in this class a function starts a thread, another function checks if the thread is still running, but when i do a request for the function that checks of the thread is still runnning, i get this error:

org.apache.axis2.AxisFault: Exception occurred while trying to invoke service method isTaskRunning at org.apache.axis2.util.Utils.getInboundFaultFromMessageContext(Utils.java:531) at org.apache.axis2.description.OutInAxisOperationClient.handleResponse(OutInAxisOperation.java:375) at org.apache.axis2.description.OutInAxisOperationClient.send(OutInAxisOperation.java:421) at org.apache.axis2.description.OutInAxisOperationClient.executeImpl(OutInAxisOperation.java:229) at org.apache.axis2.client.OperationClient.execute(OperationClient.java:165) at be.kdg.cosys.thesis.ExecutorStub.isTaskRunning(ExecutorStub.java:487) at be.kdg.cosys.thesis.AllToPublicScheduler.executeTask(AllToPublicScheduler.java:158) at be.kdg.cosys.thesis.AllToPublicScheduler.incomingApplication(AllToPublicScheduler.java:106) at be.kdg.cosys.thesis.ParserToScheduler.run(ParserToScheduler.java:111) at java.lang.Thread.run(Unknown Source)

Here's is the webservice class:

public class Executor {

private Task task = null;
private long startTime = 0;
private long runTime = 0;
private Thread taskThread=null;

public void execute(byte[] object){ 
    ObjectInputStream in = null;
    try {
        in = new ObjectInputStream(new ByteArrayInputStream(object));
        task = (Task) in.readObject();
        in.close();
    } catch (IOException | ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    runTime = task.getRunTime();
    startTime = System.currentTimeMillis();
    taskThread=new Thread(task);
    taskThread.start();
}
public long timeToFinish()
{
    return runTime-(System.currentTimeMillis()-startTime);
}
public boolean isTaskRunning()
{
    return taskThread.isAlive();        
}
public byte[] getTask()
{
    byte[] ser=null;
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    ObjectOutput out = null;
    try {
      out = new ObjectOutputStream(bos);   
      out.writeObject(task);
      ser = bos.toByteArray();
      out.close();
      bos.close();
    } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
    }   
    return ser;
}

}

On the server of the webservice i get a nullpointerexeception (log of catalina)

Can anyone help me?

Yorick

user1428716 user1428716 · Accepted Answer · 2013-02-13T20:04:43

Yes you will get a Null pointer exception - Because the Web-service method would not be called on the Same class instance which started the Thread. Since the variable taskThread will be null , and in the method isTaskRunning() calls a method on a null object, it causes a NullpointerException

Ideally , if you need to poll a Thread using web-service , you should use an intimidatory media which states the Status of Thread. intimidatory can be a Database Table which stores the Thread Status

nullpointerexception axis2 webservice

1 Answers