Question

我正在开发一个应用程序，我想在地图上显示多个标记。（标记来自数据库（dynamodb），值都在“STRING”而不是两倍）。在将double转换为所有“纬度和经度”的字符串之后，我得到java.lang.NumberFormatException的异常：无效的double：“n / a”和app崩溃。因为在表格中，一个lat长显示“na”。（如图所示）

我卡住了，不知道如何处理这个空值。我应该检查一下还是什么？提前致谢

((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMapAsync(new OnMapReadyCallback() {
    @Override
    public void onMapReady(final GoogleMap googleMap) {

        mMap = googleMap;

        final LatLng israel = new LatLng(31.0461, 34.8516);
        googleMap.addMarker(new MarkerOptions().position(israel).title("israel"));
        googleMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
        CameraPosition camPos = new CameraPosition.Builder().target(new LatLng(31.0461, 34.8516)).zoom(8).tilt(70).build();
        CameraUpdate camUpd3 = CameraUpdateFactory.newCameraPosition(camPos);
        googleMap.animateCamera(camUpd3);

        mMap.setOnMapLoadedCallback(new GoogleMap.OnMapLoadedCallback() {
            @Override
            public void onMapLoaded() {

              DDBExecutor.getInstance().getAllSettlements(mContext, new DDBExecutor.OnResponseListener() {
                  @Override
                  public void onResponse(Object result, String message) {
                      List<SettlementsTable> lstSettlements = new ArrayList<>();
                      lstSettlements.addAll((List<SettlementsTable>) result);
                      for (SettlementsTable table : lstSettlements){
                          mMap.addMarker(new MarkerOptions().position(new LatLng(Double.parseDouble(table.getX()), Double.parseDouble(table.getY()))));
                      }
                     LatLngBounds.Builder builder = new LatLngBounds.Builder();
                      builder.include(israel);
                      LatLngBounds bounds = builder.build();
                      CameraUpdate cu = CameraUpdateFactory.newLatLngBounds(bounds, 200);
                      mMap.moveCamera(cu);
                      mMap.animateCamera(CameraUpdateFactory.zoomTo(8), 2000, null);

                      try {
                          KmlLayer kmlLayer = new KmlLayer(googleMap, R.raw.settlements, getApplicationContext());
                          kmlLayer.addLayerToMap();
                          KmlLayer kmlLayer1 = new KmlLayer(googleMap, R.raw.outposts, getApplicationContext());
                          kmlLayer1.addLayerToMap();
                          KmlLayer kmlLayer2 = new KmlLayer(googleMap, R.raw.settlements_in_pal_nghbrhd, getApplicationContext());
                          kmlLayer2.addLayerToMap();

                      } catch (XmlPullParserException e) {
                          e.printStackTrace();
                      } catch (IOException e) {
                          e.printStackTrace();
                      }
                  }
              });

            }
        });

Answer 1

在@OnkarShelke给出的答案的catch块中，你可以手动添加mMap中的默认值而不是简单处理异常。像：
```
mMap.add(new MarkerOptions().position(new LatLng(10.5,1.2));
// 10.5 and 1.2 could be your default values.
```

或者因为您已经知道导致错误的错误值（n / a）例外，您可以在尝试添加到mMap之前检查该值。像：

for (SettlementsTable table : lstSettlements){
    if (table.getX().equalsIgnoreCase("n/a") || table.getY().equalsIgnoreCase("n/a")) {
        // do something like add default values
    } else {
        mMap.addMarker(new MarkerOptions().position(new LatLng(Double.parseDouble(table.getX()), Double.parseDouble(table.getY()))));
    }
}

Answer 2

环绕尝试捕捉

try {
    mMap.addMarker(new MarkerOptions().position(new 
            LatLng(Double.parseDouble(table.getX()), 
                    Double.parseDouble(table.getY()))));
} catch (NumberFormatException ex){
    //do anything when exception occurs
}

Answer 3

包含SettlementsTable对象的第一个过滤器列表，这样当对象字段中有n / a字符串时，不要将其添加到您要提供给Marker对象进行绘图的Arraylist对象。

在地图上放置多个标记时，为Latlng值获取无效的双“n \ a”

3 个答案: