java从文本文件中读取纬度和经度

Question

我目前有一个用lat和多头仓位硬编码的应用程序。相反，我想从一个名为cities的文本文件中读取lat和long。包含以下内容的文本

Dublin 53.347860 -6.272487
Kerry 52.264007 -9.686990
Cork 51.892171 -8.475068

我发现这个功能很难实现，想知道有人能帮我解决这个问题吗

这是我目前掌握的代码

地图活动

public class MapActivity extends AppCompatActivity implements OnMapReadyCallback {

String city = "";
MapFragment mf;
GoogleMap map;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_map);

    Intent I = getIntent();
    city = I.getStringExtra("city");
    mf = (MapFragment) getFragmentManager().findFragmentById(R.id.the_map);
    mf.getMapAsync(this);
}

@Override
public void onMapReady(GoogleMap map) {    // map is loaded but not laid out yet
    this.map = map;
    // code to run when the map has loaded

    double lat, lon;

    if (city.equals("Dublin"))
    {
        lat = 53.347860;
        lon = -6.272487;
    }
    else if (city.equals("Kerry"))
    {
        lat= 52.264007;
        lon= -9.686990;

    }
    else if (city.equals("Cork"))
    {
        lat= 51.892171;
        lon= -8.475068;
    }
    else
    {
        lat=0;
        lon=0;
    }

    map.addMarker(new MarkerOptions()
            .position(new LatLng(lat, lon))
            .title("")
    );

    map.moveCamera(CameraUpdateFactory.newLatLng(new LatLng(lat, lon)));
    map.moveCamera(CameraUpdateFactory.zoomTo(10));

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_map, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
}

城市碎片

public class CityListFragment extends Fragment {



public CityListFragment() {
    // Required empty public constructor
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.fragment_city_list, container, false);

    ArrayAdapter<String> adapter = new ArrayAdapter<>(this.getActivity(), 安卓.R.layout.simple_list_item_1, Arrays.asList("myLocation","Dublin","Kerry","Cork"));
    ListView list = (ListView) view.findViewById(R.id.listView);
    list.setAdapter(adapter);

    list.setOnItemClickListener(
            new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> list, View row, int index, long rowID) {
                    // code to run when user clicks that item
                    // launch new Activity with holes details
                    ((CityMap)getActivity()).setCity((String)list.getItemAtPosition(index));
                    ((CityMap)getActivity()).showMap();

                }
            }
    );
    return view;
}


}

城市地图

public class CityMap extends AppCompatActivity implements OnMapReadyCallback {

String city = "";
MapFragment mf;
GoogleMap map;
double latitude;
double longitude;

public void setCity(String city)
{
    this.city = city;
}

public void showMap()
{
    mf = (MapFragment) getFragmentManager().findFragmentById(R.id.the_map);
    if (mf == null) {
        // CityMapFragment (Fragment B) is not in the layout (handset layout),
        // so start MapActivity (Activity B)
        // and pass it the info about the selected item
        Intent intent = new Intent(this, MapActivity.class);
        intent.putExtra("city", city);
        startActivity(intent);
    } else {
        // CityMApFragment (Fragment B) is in the layout (tablet layout)
        mf.getMapAsync(this);

    }
}

@Override
public void onMapReady(GoogleMap map) {    // map is loaded but not laid out yet
    this.map = map;
    // code to run when the map has loaded

    double lat, lon;
    if (city.equals("myLocation"))
    {
        lat= latitude;
        lon= longitude;

    }

    else if (city.equals("Dublin"))
    {
        lat = 53.347860;
        lon = -6.272487;
    }
    else if (city.equals("Kerry"))
    {
        lat= 52.264007;
        lon= -9.686990;

    }

    else if (city.equals("Cork"))
    {
        lat= 51.892171;
        lon= -8.475068;
    }
    else
    {
        lat=0;
        lon=0;
    }

    map.addMarker(new MarkerOptions()
            .position(new LatLng(lat, lon))
            .title("")
    );

    map.moveCamera(CameraUpdateFactory.newLatLng(new LatLng(lat, lon)));
    map.moveCamera(CameraUpdateFactory.zoomTo(10));

}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_city_map, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
}