尝试使用以下类的Ormlite ForeignCollection时遇到问题。我相信我有我的Run＆amp; Waypoint类正确注释。 （Run有一个WayPoints集合）。但是，当我尝试访问WayPoints时（请参阅第三个代码提取），当我调用CloseableIterator时，hasNext()返回null。当我使用模拟器测试时，我首先为Run生成一些WayPoints并存储它们。然后我尝试通过Run实例访问这些WayPoints。只是为了完成图片而不在这里转储太多代码，ForeignCollection<WayPoint>对象通过调用
run.getWayPoints();
这里是我如何创建一个WayPoint并存储它:: - 当GPSLocation.onLocationChanged（）触发并且状态为GPS_STATE_RUNNING时，则调用createWayPoint（）。这将实例化WayPoint，设置lng / lat值，并设置相关Run实例的句柄，此时此实例尚未将其自身存储到db。 Intent被发送到另一个类，该类在GPSLocation.updateWayPointWithElapsedTime（）上回调，其中WayPoint最终存储到db。当运行完成时，外部类调用storeRun（）来存储Run实例。我开始想知道当WayPoint的相关Run实例本身尚未存储时是否存储WayPoint是问题的一部分。
**注意::这些类不会被编译，因为它们被缩减以显示与问题相关的部分。
@DatabaseTable
public class Run {
@DatabaseField(generatedId=true)
private int id;
@DatabaseField(foreign=true,foreignAutoRefresh=true)
private Route route;
@ForeignCollectionField
private ForeignCollection<WayPoint> wayPoints;
@DatabaseField
private Date date;
@DatabaseField
private long time;
public ForeignCollection<WayPoint> getWayPoints() {
return wayPoints;
}
}
@DatabaseTable
public class WayPoint {
@DatabaseField(generatedId=true)
private int id;
@DatabaseField
private int latitude;
@DatabaseField
private int longitude;
@DatabaseField
private int time; // offset
@DatabaseField(foreign=true,foreignAutoRefresh=true)
private Run run;
}
public class Contender implements Comparable<Contender> {
private int accumulatedDistance;
private int interpolatedDistance;
private WayPoint startPoint;
CloseableIterator itr;
private int id;
WayPoint previous;
WayPoint next;
public Contender(ForeignCollection<WayPoint> wayPoints, WayPoint startPoint, int id) {
this.startPoint = startPoint;
this.id = id;
itr = wayPoints.closeableIterator();
if(itr.hasNext()) {
next = (WayPoint)itr.next();
}
else {
Log.e("@@@", "no way points");
}
Log.i("@@@", "wayPoints size is " + wayPoints.size());
}
}
public class GPSLocation extends Service implements LocationListener {
private Run run;
private WayPoint wayPoint;
private int distanceTravelled;
@Override
public void onCreate() {
locationManager = (LocationManager)getSystemService(LOCATION_SERVICE);
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, false);
startLocationUpdates = new ArrayList<Location>();
Log.i(LOGTAG, "GPSLocation Service Running...");
}
public void startRunning() {
setState(GPS_STATE_RUNNING);
startTime = System.currentTimeMillis();
run = new Run();
run.setRoute(route);
run.setDate(new Date());
}
public void storeRun(long elapsedTime) {
// if first run and end point not set then set end point
run.setTime(elapsedTime);
route.addToCumulativeDistance(distanceTravelled);
DatabaseManager.getInstance().storeRun(run);
DatabaseManager.getInstance().updateRoute(route);
resetGlobalState();
}
public void onLocationChanged(Location location) {
previousLocation = currentLocation;
currentLocation = location;
Intent i = null;
boolean startActivity = true;
switch(state)
{
case GPS_STATE_SETTING_START_LOCATION:
startLocationUpdates.add(location);
if(startLocationAccepted())
{
i = new Intent(this, AddRoute.class);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
i.setAction("acquired");
}
else
{
startActivity = false; // waiting for more location data
}
break;
case GPS_STATE_READY:
if(!atLocation(ROUTE_START, location, ROUTE_DELIMITER_REQUIRED_PROXIMITY))
{
setState(GPS_STATE_AWAITING_ARRIVAL_AT_START_LOCATION);
i = new Intent(this, Running.class);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
i.setAction("proximity_update");
}
break;
case GPS_STATE_AWAITING_ARRIVAL_AT_START_LOCATION:
i = new Intent(this, Running.class);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
if(atLocation(ROUTE_START, location, ROUTE_DELIMITER_REQUIRED_PROXIMITY))
{
setState(GPS_STATE_READY);
i.setAction("ready");
}
else
{
i.setAction("proximity_update");
}
break;
case GPS_STATE_RUNNING:
createWayPoint(location);
i = new Intent(this, Running.class);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
if(atLocation(ROUTE_END, location, ROUTE_DELIMITER_REQUIRED_PROXIMITY)
&& (distanceTravelled > ROUTE_DELIMITER_REQUIRED_PROXIMITY))
{
i.setAction("at_end");
}
else
{
i.setAction("update");
}
distanceTravelled += currentLocation.distanceTo(previousLocation);
i.putExtra("distanceTravelled", distanceTravelled);
setState(GPS_STATE_RUNNING_UPDATE);
break;
default:
// error
}
}
private void createWayPoint(Location location) {
wayPoint = new WayPoint();
wayPoint.setLatitude(LocationMath.degreesToMicroDegrees(location.getLatitude()));
wayPoint.setLongitude(LocationMath.degreesToMicroDegrees(location.getLongitude()));
wayPoint.setRun(run);
}
/*
* Now we have the elapsed time from the Running Activity, we can store this WayPoint
*/
public void updateWayPointWithElapsedTime(long elapsedTime) {
// TODO::check the time value is correct
wayPoint.setTimeOffset((int)elapsedTime);
DatabaseManager.getInstance().storeWayPoint(wayPoint);
setState(GPS_STATE_RUNNING);
}
}
摘自DatabaseManager - ＆gt;
public void storeWayPoint(WayPoint point) {
try {
getHelper().getWayPointDao().create(point);
} catch (SQLException e) {
e.printStackTrace();
}
}
public void storeRun(Run run) {
try {
getHelper().getRunDao().create(run);
} catch (SQLException e) {
e.printStackTrace();
}
}
答案 0 :(得分：1)
我发现你发布Chris的代码没有任何问题。因此我怀疑你没有像你认为的那样插入WayPoint。你确认他们在数据库中吗？您是否直接使用WayPoint DAO尝试了查询？
// what does this return?
List<WayPoint> wayPoints = wayPointDao.queryForAll();
我首先为Run生成一些WayPoints并存储它们
此外，请确保您已将Run字段插入Run表并在每个WayPoint 上设置它，然后为{创建{ {1}}。你应该做的事情如下：
WayPoint您可以插入的另一种方法是使用外部集合本身：
Run run1 = new Run(...);
runDao.create(run1);
...
WayPoint wayPoint1 = new WayPoint(...);
wayPoint1.setRun(run1);
wayPointDao.create(wayPoint1);
...
如果您编辑问题并向我们展示用于将// create a foreign collection we can add to
run.wayPoints = runDao.getEmptyForeignCollection("wayPoints");
// now if you add something to the collection, it gets created in the DAO as well
run.wayPoints.add(wayPoint1);
插入数据库的代码，我将编辑我的答案以提供更多信息。