【发布时间】：2019-04-07 10:44:40
【问题描述】：
我正在创建一个导航应用程序，它将显示新加坡的所有停车场位置。我有 2 个课程，HomeUI 和 Appmanager。 HomeUI 将解析来自 carpark API 的 json 数据并将其存储在 arraylist 中。然后我创建了一个名为 getarraylist() 的方法，以便我的 Appmanager 可以访问此方法并获取 arraylist 中的值。但是，我只能打印出数组列表的最后一个值，我没有其他想法了。请检查我的代码，看看是否可以改进。
HomeUI 类：
package teamjake.com.drivesafe.Boundary;
import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Location;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.design.widget.NavigationView;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.content.ContextCompat;
import android.support.v4.view.GravityCompat;
import android.support.v4.view.ViewPager;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.ScrollView;
import android.widget.TextView;
import android.widget.Toast;
import com.android.volley.AuthFailureError;
import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.places.ui.PlaceAutocompleteFragment;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import teamjake.com.drivesafe.AppController;
import teamjake.com.drivesafe.CarparkAvailabilityUI;
import teamjake.com.drivesafe.Control.AppManager;
import teamjake.com.drivesafe.Control.UserAccountManager;
import teamjake.com.drivesafe.Const;
import teamjake.com.drivesafe.R;
import teamjake.com.drivesafe.RoadWorksUI;
import teamjake.com.drivesafe.TrafficIncidentUI;
public class HomeUI extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener, OnMapReadyCallback {
private SupportMapFragment mMap;
PlaceAutocompleteFragment placeAutoComplete;
private GoogleApiClient googleApiClient;
private LocationRequest locationRequest;
private Location lastLocation;
private LocationManager locManager;
private TextView nametxtView;
private Marker currentUserLocationMarker;
private static final int Request_User_Location_Code = 99;
private double latitude, longitude;
private int ProximityRadius = 10000;
public HashMap<String, String> cpItems = new HashMap<String, String>();
private GoogleMap map1;
private static String TAG = HomeUI.class.getSimpleName();
private String tag_json_obj = "jobj_req";
private String tag_json_arry = "jarray_req";
private String jsonResponse;
public ArrayList<HashMap<String, String>> carparkList = new ArrayList<HashMap<String, String>>();
private TextView txtResponse;
// Google Map
// private GoogleMap googleMap;
// Latitude & Longitude
private Double Latitude = 0.00;
private Double Longitude = 0.00;
//From -> the first coordinate from where we need to calculate the distance
private double fromLongitude;
private double fromLatitude;
//To -> the second coordinate to where we need to calculate the distance
private double toLongitude;
private double toLatitude;
//Our buttons
// private Button direction;
ScrollView scrollview;
LinearLayout linearLayout;
private Toolbar toolbar;
private TabLayout tabLayout;
private ViewPager viewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
// direction = (Button) findViewById(R.id.direction);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(viewPager);
setupTabIcons();
//For Navigation Drawer
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
View header = navigationView.getHeaderView(0);
nametxtView = (TextView) header.findViewById(R.id.nametxtView);
nametxtView.setText(UserAccountManager.str_username);
}
@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.home, menu);
return true;
}
private void setupViewPager(ViewPager viewPager) {
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFrag(new AppManager(), "ONE");
adapter.addFrag(new TrafficIncidentUI(), "TWO");
adapter.addFrag(new RoadWorksUI(), "THREE");
adapter.addFrag(new CarparkAvailabilityUI(), "FOUR");
viewPager.setAdapter(adapter);
}
private void setupTabIcons() {
int[] tabIcons = {
R.drawable.ic_map,
R.drawable.ic_traffic,
R.drawable.ic_roadwork,
R.drawable.ic_carpark
};
tabLayout.getTabAt(0).setIcon(tabIcons[0]);
tabLayout.getTabAt(1).setIcon(tabIcons[1]);
tabLayout.getTabAt(2).setIcon(tabIcons[2]);
tabLayout.getTabAt(3).setIcon(tabIcons[3]);
}
@Override
public void onMapReady(GoogleMap googleMap) {
}
class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager manager) {
super(manager);
}
@Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
@Override
public int getCount() {
return mFragmentList.size();
}
public void addFrag(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public CharSequence getPageTitle(int position) {
// return null to display only the icon
return null;
}
}//For Navigation Drawer
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
// Items listed here are from activity_home_drawer.xml
if (id == R.id.trafficIncident) {
} else if (id == R.id.roadWorks) {
} else if (id == R.id.carPark) {
jsonArrayCarpark();
} else if (id == R.id.nav_share) {
} else if (id == R.id.nav_send) {
} else {
//Log out from the page
Intent backToLogIn = new Intent(this, LoginUI.class);
// backToLogIn.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
// backToLogIn.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
// backToLogIn.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
// backToLogIn.putExtra("key",1);
startActivity(backToLogIn);
Toast.makeText(this, "Thank you and see you again :)", Toast.LENGTH_LONG).show();
// finish();
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
private void jsonArrayCarpark() {
JsonObjectRequest jsonObjReq = new JsonObjectRequest(Request.Method.GET,
Const.URL_CarparkAvailability, null,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
String metadata = response.getString("odata.metadata");
JSONArray value = response.getJSONArray("value");
String carparkID = "";
String area = "";
String development = "";
String location = "";
String availableLots = "";
String lotType = "";
String agency = "";
for (int i = 0; i < value.length(); i++) {
JSONObject carparkInfo = value.getJSONObject(i);
carparkID = carparkInfo.getString("CarParkID");
area = carparkInfo.getString("Area");
development = carparkInfo.getString("Development");
location = carparkInfo.getString("Location");
String[] loc = location.split("\\s+");
double latitude = Double.parseDouble(loc[0]);
double longitude = Double.parseDouble(loc[1]);
availableLots = carparkInfo.getString("AvailableLots");
lotType = carparkInfo.getString("LotType");
agency = carparkInfo.getString("Agency");
jsonResponse = "";
jsonResponse += "carparkID: " + carparkID + "\n\n";
jsonResponse += "Area: " + area + "\n\n";
jsonResponse += "Latitude: " + latitude + "\n\n";
jsonResponse += "Longitude: " + longitude + "\n\n";
jsonResponse += "development: " + development + "\n\n";
jsonResponse += "location: " + location + "\n\n";
jsonResponse += "availablelots: " + availableLots + "\n\n";
jsonResponse += "lotType: " + lotType + "\n\n";
jsonResponse += "Agency: " + agency + "\n\n";
Toast.makeText(getApplicationContext(), jsonResponse, Toast.LENGTH_SHORT).show();
cpItems = new HashMap<>();
carparkList = new ArrayList<HashMap<String, String>>();
//cpItems.put("CarParkID", carparkID);
cpItems.put("Area", area);
cpItems.put("Development", development);
cpItems.put("Location", location);
cpItems.put("Latitude", String.valueOf(latitude));
cpItems.put("Longitude", String.valueOf(longitude));
cpItems.put("AvailableLots", availableLots);
cpItems.put("LotType", lotType);
cpItems.put("Agency", agency);
Log.v(TAG, "Testinside: E" + cpItems);
carparkList.add(cpItems);
}
} catch (JSONException e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(),
"Error: " + e.getMessage(),
Toast.LENGTH_LONG).show();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
AlertDialog.Builder add = new AlertDialog.Builder(HomeUI.this);
add.setMessage(error.getMessage()).setCancelable(true);
AlertDialog alert = add.create();
alert.setTitle("Error!!!");
alert.show();
}
}) {
@Override
public Map<String, String> getHeaders() throws AuthFailureError {
HashMap<String, String> headers = new HashMap<String, String>();
headers.put("accept", "application/json");
headers.put("AccountKey", Const.API_DataMall);
return headers;
}
};
// Adding request to request queue
AppController.getInstance().addToRequestQueue(jsonObjReq,
tag_json_obj);
// Cancelling request
// ApplicationController.getInstance().getRequestQueue().cancelAll(tag_json_obj);
}
public ArrayList<HashMap<String, String>> getarraylist() {
Log.v(TAG, "testgethasmap: E" + carparkList);
return carparkList;
}
public void setHashmap(ArrayList<HashMap<String, String>> carparkList) {
this.carparkList = carparkList;
//getarraylist();
Log.v(TAG, "testsethasmap: E" + carparkList);
}
}
AppManager 类：
HomeUI ex = new HomeUI();
hm = ex.getarraylist();
Log.v(TAG, "testhashmap: E" + hm);
if(hm!=null)
{
for (int i = 0; i < hm.size(); i++) {
String name = hm.get(i).get("Area").toString();
latitude = Double.parseDouble(hm.get(i).get("Latitude").toString());
longitude = Double.parseDouble(hm.get(i).get("Longitude").toString());
MarkerOptions marker = new MarkerOptions().position(new LatLng(latitude, longitude)).title(name);
googleMap.addMarker(marker);
}
}
更新
目前，我还有一个问题。根据user guide，他们的 API 响应限制为每次调用 500 条记录。 API 获取请求方法是这样的：http://datamall2.mytransport.sg/ltaodataservice/CarParkAvailabilityv2
要获取接下来的 500 条记录，我必须将 $skip 附加到如下所示的 URL：http://datamall2.mytransport.sg/ltaodataservice/CarParkAvailabilityv2?$skip=500
除了多次调用 API 之外，有没有人知道获取所有记录？
【问题讨论】：
标签： android json google-maps android-studio arraylist