从文本文件中读取纬度和经度 [英] Reading latitude and longitude from a text file
本文介绍了从文本文件中读取纬度和经度的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我目前有一个硬件编码的经纬度和长仓。相反，我想从一个名为cities.text的文本文件中读取lat和long，其中包含以下内容：
$ p $ Dublin $ 53.347860 -6.272487
凯利52.264007 -9.686990
软木51.892171 -8.475068
可以使用一些帮助，因为我'找到这个功能很难实现，并想知道有人可以帮我完成这个工作吗？。
这是我到目前为止的代码。
地图活动
public class MapActivity扩展AppCompatActivity实现的OnMapReadyCallback {
String city =;
MapFragment mf;
GoogleMap地图;
@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已加载，但尚未布局
this.map = map;
//在地图加载时运行代码
double lat，lon;
if（city.equals（Dublin））
{
lat = 53.347860;
lon = -6.272487;
}
else if（city.equals（Kerry））
{
lat = 52.264007;
lon = -9.686990;
$ b else if（city.equals（Cork））
{
lat = 51.892171;
lon = -8.475068;
}
else
{
lat = 0;
lon = 0;
$ b map.addMarker（new MarkerOptions（）
.position（new LatLng（lat，lon））
.title（）
）;
map.moveCamera（CameraUpdateFactory.newLatLng（new LatLng（lat，lon）））;
map.moveCamera（CameraUpdateFactory.zoomTo（10））;
$ b @Override
public boolean onCreateOptionsMenu（菜单菜单）{
//膨胀菜单;这会将项目添加到操作栏（如果存在）。
getMenuInflater（）。inflate（R.menu.menu_map，menu）;
返回true;
}
@Override
public boolean onOptionsItemSelected（MenuItem item）{
// Handle action bar item clicks here here。操作栏将
//自动处理Home / Up按钮上的点击，只要您在AndroidManifest.xml中指定了一个父活动，就可以长按
//。
int id = item.getItemId（）;
// noinspection SimplifiableIfStatement
if（id == R.id.action_settings）{
return true;
}
返回super.onOptionsItemSelected（item）;
CityListFragment
public class CityListFragment extends Fragment {
$ b public CityListFragment（）{
//必须为空public构造函数
}
@Override
public void onCreate（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）;
$ b @覆盖
public View onCreateView（LayoutInflater inflater，ViewGroup容器，
Bundled savedInstanceState）{
View view = inflater。 inflate（R.layout.fragment_city_list，container，false）;
ArrayAdapter< String> adapter）= new ArrayAdapter<>（this.getActivity（），android.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 $ b $ public void onItemClick（AdapterView<> list，View row，int index， long rowID）{
//用户单击该项目时运行的代码
//启动新的具有孔详细信息的活动
（（CityMap）getActivity（））。setCity（（String）list。 getItemAtPosition（index））;
（（CityMap）getActivity（））。showMap（）;
}
}
）;
返回视图;
}
}
CityMap p>
public class CityMap extends AppCompatActivity implements OnMapReadyCallback {
String city =;
MapFragment mf;
GoogleMap地图;
双纬度;
双经度;
public void setCity（String city）
{
this.city = city;
$ b $ public void showMap（）
{
mf =（MapFragment）getFragmentManager（）。findFragmentById（R.id.the_map）;
if（mf == null）{
// CityMapFragment（Fragment B）不在布局中（手机布局），
//启动MapActivity（Activity B）
//并将它传递给选定项目的信息
Intent intent = new Intent（this，MapActivity.class）;
intent.putExtra（city，city）;
startActivity（intent）;
} else {
// CityMApFragment（Fragment B）在布局中（平板布局）
mf.getMapAsync（this）;
$ b @Override
public void onMapReady（GoogleMap map）{// map已加载但尚未布局
this.map = map;
//在地图加载时运行代码
double lat，lon;
if（city.equals（myLocation））
{
lat = latitude;
lon = longitude;
$ b else if（city.equals（Dublin））
{
lat = 53.347860;
lon = -6.272487;
}
else if（city.equals（Kerry））
{
lat = 52.264007;
lon = -9.686990;
$ b else if（city.equals（Cork））
{
lat = 51.892171;
lon = -8.475068;
}
else
{
lat = 0;
lon = 0;
$ b map.addMarker（new MarkerOptions（）
.position（new LatLng（lat，lon））
.title（）
）;
map.moveCamera（CameraUpdateFactory.newLatLng（new LatLng（lat，lon）））;
map.moveCamera（CameraUpdateFactory.zoomTo（10））;
$ b $ @覆盖
保护无效onCreate（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）;
setContentView（R.layout.main）;
}
@Override
public boolean onCreateOptionsMenu（菜单菜单）{
//膨胀菜单;这会将项目添加到操作栏（如果存在）。
getMenuInflater（）。inflate（R.menu.menu_city_map，menu）;
返回true;
}
@Override
public boolean onOptionsItemSelected（MenuItem item）{
// Handle action bar item clicks here here。操作栏将
//自动处理Home / Up按钮上的点击，只要您在AndroidManifest.xml中指定了一个父活动，就可以长按
//。
int id = item.getItemId（）;
// noinspection SimplifiableIfStatement
if（id == R.id.action_settings）{
return true;
}
返回super.onOptionsItemSelected（item）;
$ div $解析方案假设你可以使用这个函数在你的assets文件夹中包含lat-lng数据，你可以使用这个函数
private HashMap< ;字符串，位置> readFile（String path）{
HashMap< String，Location> citiesLoactionMap = new HashMap<>（）;
String dump = null;
尝试{
dump = readFromAssets（mContext，path）;
} catch（IOException e）{
e.printStackTrace（）;
if（dump！= null&&！dump.isEmpty（））{
String [] cities = dump.split（\\\
） ;
（String city：cities）{
String [] cityData = city.split（\\s +）; （cityData [0]！= null& cityData [1]！= null& cityData [2]！= null）{
位置位置=新位置（cityData [0]）;
location.setLatitude（Double.parseDouble（cityData [1]））;
location.setLongitude（Double.parseDouble（cityData [2]））;
citiesLoactionMap.put（cityData [0]，location）;
}
}
}
return citiesLoactionMap;
}
这里路径就是文件名，例如cities.txt
I currently have an application hard coded with lat and long positions. Instead I want to read the lat and long from a text file called cities.text which contains the following
Dublin 53.347860 -6.272487
Kerry 52.264007 -9.686990
Cork 51.892171 -8.475068
Could use some help as I'm finding this feature difficult to implement and was wondering could someone help me with how this is done?.
Here's the code I have so far.
Map Activity
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);
}
}
CityListFragment
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(), android.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;
}
}
CityMap
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);
}
}
解决方案 Assuming you have this file in your assets folder with the lat-lng data in the above format, you can use this function
private HashMap<String, Location> readFile(String path){
HashMap<String, Location> citiesLoactionMap = new HashMap<>();
String dump = null;
try {
dump = readFromAssets(mContext, path);
} catch (IOException e) {
e.printStackTrace();
}
if (dump != null && !dump.isEmpty()) {
String[] cities = dump.split("\n");
for(String city : cities){
String[] cityData = city.split("\\s+");
if(cityData[0] != null && cityData[1] != null && cityData[2] != null){
Location location = new Location(cityData[0]);
location.setLatitude(Double.parseDouble(cityData[1]));
location.setLongitude(Double.parseDouble(cityData[2]));
citiesLoactionMap.put(cityData[0], location);
}
}
}
return citiesLoactionMap;
}
Here path would be the the file name, e.g. "cities.txt"
这篇关于从文本文件中读取纬度和经度的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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