java bean空指针异常

Question

This is my first post, so hopefully I live up to the high standards of the community.

I'm trying to learn Enterprise Java beans and I've been thrown into the deep end and asked to debug an EAR file that's throwing a NullPointerException . This is the line that's throwing the Exception:

private CrashMonitorTimer crash;
...
/*THE NEXT LINE THROWS THE NULL POINTER EXCEPTION*/
crash.createTimer(Long.parseLong(sCrashMonitorInterval),"CrashMoniterScheduler");

This is the code for the interface being called:

import javax.ejb.Local;

@Local
public interface CrashMonitorTimer
{
    public abstract void createTimer(long l, String s);

    public abstract void cancelTimer(String s);
}

And this is the code for the Java bean:

@Stateless(name = "CrashMonitorBean", mappedName = "CrashMonitorBean")
@Local(CrashMonitorTimer.class)

public class CrashMonitorBean
    implements CrashMonitorTimer
{

    @Resource
    SessionContext sessionCtx;
    TimerService timerService;
    Timer timer;
    int iMsgCntBeforeCtxRenew;
    int iCtxReusedCount;
    Context _context;
    CrashMonitorInfoUtil crashMonitorRMIContext[];

    public CrashMonitorBean()
    {
        iMsgCntBeforeCtxRenew = 10;
        iCtxReusedCount = 0;
        _context = null;
        crashMonitorRMIContext = null;
    }

    @Override
    public void createTimer(long lInterval, String sName)
    {

        //CrashMonitorInfoUtil leaves context open for reuse 

        System.out.println((new StringBuilder("Creating ")).append(sName).append(" timer").toString());
        timerService = sessionCtx.getTimerService();
        timer = timerService.createTimer(lInterval, lInterval, sName);
        String sPorts = SystemConfigurator.getConfigValue("RMIPorts");
        String saPorts[] = sPorts.split(",");
        String server = SystemConfigurator.getConfigValue("host");
        crashMonitorRMIContext = new CrashMonitorInfoUtil[saPorts.length];
        for(int i = 0; i < saPorts.length; i++)
        {
            crashMonitorRMIContext[i] = new CrashMonitorInfoUtil(server, saPorts[i]);
        }

    }
...
}

I've poked around at this, but having had zero experience with Java beans or interfaces (or the new annotations) I'm kind of at a loss on what I should even try. Any explanation or direction would be greatly appreciated.

Answer 1

crash variable is null .

If sCrashMonitorInterval were null, then it would have thrown NumberFormatException