Question

这是我的第一篇文章，希望我能够达到社区的高标准。

我正在尝试学习企业Java bean，并且我已被抛入深层，并要求调试一个抛出NullPointerException的EAR文件。这是抛出异常的行：

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

这是被调用接口的代码：

import javax.ejb.Local;

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

    public abstract void cancelTimer(String s);
}

这是Java bean的代码：

@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]);
        }

    }
...
}

我已经开始讨论这个问题，但是对于Java bean或接口（或新注释）没有经验，我对我应该尝试的东西感到很茫然。任何解释或指示都将不胜感激。

Answer 1

crash变量为null。

如果sCrashMonitorInterval为空，则会抛出NumberFormatException

java bean空指针异常

1 个答案: