java.lang.NullPointerException

以下是我的代码：（第一句执行完后就出现"页面访问时发生错误: null ”的错误信息）

public String deleteRecordSet(boolean isSuccess) throws Exception {
TaskLog entitylog = managerlog.getPreEvent(this.getOperateId()); //得到单据以前的待办事宜记录

if (entitylog != null) {
entitylog.setIsremind(new Integer(0)); //修改提醒状态

managerlog.saveTaskLog(entitylog); //提交状态变更

}
//下面插入新日志
entitylog = new TaskLog();
entitylog.setCzr(manager.getUserByUserId(manager.getLoginUserId()));
entitylog.setCzobject("RWBG");
entitylog.setCzobjectid(this.getOperateId());
entitylog.setCzdttm(new java.sql.Date(System.currentTimeMillis()));
entitylog.setCztip("删除了任务变更单!");
entitylog.setIsremind(new Integer(0));
entitylog.setCzmodule("taskChange!delete.action?operateId="+this.getOperateId());
entitylog.setTxr(manager.getTaskCheck(this.getOperateId()).getTxr());
entitylog.setIsclose(new Integer(0));
//logger.debug("日志保存前");
managerlog.saveTaskLog(entitylog); //为存储新日志记录结束


manager.deleteId(this.getOperateId());
return RELOAD;
}

//以下两个方法是形成jsonlist begin
@Override
public Page<TaskCheck> getPageRecords(Page<TaskCheck> page){//输出页面属性

return manager.getAllTaskCheck(page);
}




主要错误信息：

at com.suun.web.prjplan.CheckAction.saveRecordSet(CheckAction.java:147)
at com.suun.web.prjplan.CheckAction.saveRecordSet(CheckAction.java:1)
at com.suun.modules.web.struts2.CRUDActionSupport.save(CRUDActionSupport.java:107)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:434)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:273)