ArrayList覆蓋所有以前存儲的值android

Question

我試圖計算一個位置（源位置標記）與存儲在ArrayList中的其他位置（從RoutesData返回）之間的距離，並沿另一個ArrayList中的距離存儲位置。但是當我在該陣列中添加一個位置和距離源位置的距離時，它將覆蓋所有先前存儲的位置和距離，並且新添加的位置和距離。我爲特定邏輯編寫代碼。

類RoutesData：返回LatLngs測量距離

public class RoutesData { 



    public ArrayList<LatLng> allRoutesMainStops(){ 
     ArrayList<LatLng> allPoints = new ArrayList<LatLng>(Arrays.asList(
       //icPoints 
       new LatLng(33.582752, 73.044503),new LatLng(33.595504, 73.050912), 
       //station 
       new LatLng(33.601097, 73.047798),new LatLng(33.598755, 73.055607),new LatLng(33.599970, 73.063225),new LatLng(33.602757, 73.066996),new LatLng(33.604297, 73.075843),new LatLng(33.608692, 73.082024), 
       //ali nawaz 
       new LatLng(33.617330, 73.081743), 
       //centre hosp 
       new LatLng(33.630072, 73.071996),new LatLng(33.631454, 73.072416),new LatLng(33.633905, 73.062379),new LatLng(33.641462, 73.063376),new LatLng(33.646714, 73.064095),new LatLng(33.651782, 73.064535),new LatLng(33.661329, 73.063974),new LatLng(33.672490, 73.055906),new LatLng(33.683642, 73.047215),new LatLng(33.689706, 73.030363),new LatLng(33.680982, 73.018654),new LatLng(33.671293, 73.016894), 
       //gpo 1 
       new LatLng(33.595215, 73.051496),new LatLng(33.593119, 73.054184),new LatLng(33.585280, 73.066763),new LatLng(33.588925, 73.076172),new LatLng(33.599117, 73.080001),new LatLng(33.607101, 73.083641),new LatLng(33.626583, 73.075027), 
       //new LatLng(33.630072, 73.071996), //duplicate center 
       new LatLng(33.631550, 73.072534),new LatLng(33.639063, 73.075742),new LatLng(33.643424, 73.077372),new LatLng(33.650480, 73.080152),new LatLng(33.663188, 73.085446),new LatLng(33.696970, 73.062966),new LatLng(33.699527, 73.073920),new LatLng(33.704257, 73.082993),new LatLng(33.707380, 73.088906),new LatLng(33.717143, 73.082961), new LatLng(33.718617, 73.084589), new LatLng(33.720660, 73.083891), new LatLng(33.727328, 73.073823), new LatLng(33.720397, 73.058392), new LatLng(33.733174, 73.087104) 

       )); 
     return allPoints; 
    } 

} 

類LocationDistances：結合位置的距離。

public class LocationDistances { 
    LatLng locs; 
    double distances; 
} 

getOverAllRoute（）方法在MainActivity：哪個源地點與所有LatLngs比較從的RouteData類返回並以列表srcLocDisList存儲它們。我遇到的所有麻煩都在第一循環，它正在計算距離，然後將距離和位置添加到srcDistList，但是當添加新對象時，它會用新添加的對象覆蓋所有以前的對象。

public void getOverAllRoute(){ 
     //to get main route points to measure distance from 
     RoutesData rD = new RoutesData(); 
     ArrayList<LatLng> mainRoutePoints = rD.allRoutesMainStops(); 
     //Toast.makeText(this,"Size: "+mainRoutePoints.size(), Toast.LENGTH_LONG).show(); 
     //to store location + distances from source 
     LocationDistances srcLocDis = new LocationDistances(); 
     ArrayList<LocationDistances> srcLocDisList = new ArrayList(); 
     //showMarkerslongLat(); 
     //create source Location 
     Location srcLoc = new Location(""); 
     srcLoc.setLatitude(sll.latitude); 
     srcLoc.setLongitude(sll.longitude); 

     // to compare distances from source location 
     Location mainPointsLoc = new Location(""); 
     for(int i =0;i<mainRoutePoints.size();i++){ 

      mainPointsLoc.setLatitude(mainRoutePoints.get(i).latitude); 
      mainPointsLoc.setLongitude(mainRoutePoints.get(i).longitude); 
      //store distances and location in arraylist 
      srcLocDis.locs = mainRoutePoints.get(i); 
      srcLocDis.distances = srcLoc.distanceTo(mainPointsLoc); 



      srcLocDisList.add(srcLocDis); 
      Log.d("Location data: ",srcLocDis.locs.toString()); 
      Log.d("Saved Data: ",srcLocDisList.get(i).toString()); 

     } 
     //Toast.makeText(this,"items1: "+srcLocDisList.size(), Toast.LENGTH_LONG).show(); 
     LocationDistances min=null; 
     for(LocationDistances x:srcLocDisList){ 
      String srcLocDisLocFile = x.locs.latitude+" "+x.locs.longitude+" distances:"+x.distances; 


      min=(min==null||x.distances<min.distances)?x:min; 
      Log.d("LocDist:",Double.toString(x.distances)); 

     } 
     LatLng srcStartMin=min.locs; 
     Toast.makeText(this,srcStartMin.latitude+" "+srcStartMin.longitude+" Distance"+Double.toString(min.distances), Toast.LENGTH_LONG).show(); 

    } 

Answer 1

把LocationDistances srcLocDis = new LocationDistances();放在循環內，否則你總是改變同一個對象。

for(int i =0;i<mainRoutePoints.size();i++){ 
    LocationDistances srcLocDis = new LocationDistances(); 
    .... 
}