java - 如何访问主要 Activity 来获取纬度和经度以便更改 url，以及如何自动更改 url 的语言，

Question

我正在做一个厕所 Android 应用程序，它可以获取最近的厕所，但我遇到了问题。我想获取mainactivity的纬度和经度变量，以便更改main2activty中url的纬度和经度信息。如何在不同的 Activity 之间传递值？感谢您的帮助。下面是我的 mainactivity 和 main2activity java 代码。

这是我的mainactivty

package hk.android.1;

import android.Manifest;
import android.annotation.SuppressLint;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Location;
import android.net.Uri;
import android.os.Bundle;
import android.provider.Settings;
import android.support.annotation.NonNull;
import android.support.design.widget.Snackbar;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import com.google.android.gms.location.FusedLocationProviderClient;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;

import java.util.Locale;

public class MainActivity extends AppCompatActivity {
    private static final String TAG1 = MainActivity.class.getSimpleName();
    private Button button3;
    private Button button4;
    private Button button5;
    private Button button6;
    public static double latitude;
    public static double longitube;
    private static final int REQUEST_PERMISSIONS_REQUEST_CODE = 34;
    private FusedLocationProviderClient mFusedLocationClient;

    protected Location mLastLocation;

    private String mLatitudeLabel;
    private String mLongitudeLabel;
    private TextView mLatitudeText;
    private TextView mLongitudeText;

    @SuppressLint("SetTextI18n")
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button3 = findViewById(R.id.button_3);
        button3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                openMain2Activity();
            }
        });

        button4 = findViewById(R.id.button4);
        button4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                openMain3Activity();
            }
        });

        button5 = findViewById(R.id.button5);
        button5.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                openMain4Activity();
            }
        });

        button6 = findViewById(R.id.button6);
        button6.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                openMain5Activity();
            }
        });

        mLatitudeLabel = getResources().getString(R.string.latitude_label);
        mLongitudeLabel = getResources().getString(R.string.longitude_label);
        mLatitudeText = findViewById((R.id.latitude_text));
        mLongitudeText = findViewById((R.id.longitude_text));

        mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);
    }

    public void openMain2Activity(){
        Intent intent = new Intent(this, Main2Activity.class);
        startActivity(intent);
    }

    public void openMain3Activity(){
        Intent intent = new Intent(this, Main3Activity.class);
        startActivity(intent);
    }
    public void openMain4Activity(){
        Intent intent = new Intent(this, Main4Activity.class);
        startActivity(intent);
    }
    public void openMain5Activity(){
        Intent intent = new Intent(this, Main5Activity.class);
        startActivity(intent);
    }

    @Override
    public void onStart() {
        super.onStart();

        if (!checkPermissions()) {
            requestPermissions();
        } else {
            getLastLocation();
        }
    }

    @SuppressWarnings("MissingPermission")
    public void getLastLocation() {
        mFusedLocationClient.getLastLocation()
                .addOnCompleteListener(this, new OnCompleteListener<Location>() {
                    @Override
                    public void onComplete(@NonNull Task<Location> task) {
                        if (task.isSuccessful() && task.getResult() != null) {
                            mLastLocation = task.getResult();

                            mLatitudeText.setText(String.format(Locale.ENGLISH, "%s: %f",
                                    mLatitudeLabel,
                                    mLastLocation.getLatitude()));

                            latitude = mLastLocation.getLatitude();
                            String lat = Double.toString(latitude);
                            TextView textView = findViewById(R.id.textView);
                            textView.setText(lat);

                            mLongitudeText.setText(String.format(Locale.ENGLISH, "%s: %f",
                                    mLongitudeLabel,
                                    mLastLocation.getLongitude()));

                            longitube = mLastLocation.getLongitude();
                            String longt = Double.toString(longitube);
                            TextView textView2 = findViewById(R.id.textView2);
                            textView2.setText(longt);

                        } else {
                            Log.w(TAG1, "getLastLocation:exception", task.getException());
                            showSnackbar(getString(R.string.no_location_detected));
                        }
                    }
                });
    }

    private void showSnackbar(final String text) {
        View container = findViewById(R.id.main_activity_container);
        if (container != null) {
            Snackbar.make(container, text, Snackbar.LENGTH_LONG).show();
        }
    }

    private void showSnackbar(final int mainTextStringId, final int actionStringId,
                              View.OnClickListener listener) {
        Snackbar.make(findViewById(android.R.id.content),
                getString(mainTextStringId),
                Snackbar.LENGTH_INDEFINITE)
                .setAction(getString(actionStringId), listener).show();
    }

    private boolean checkPermissions() {
        int permissionState = ActivityCompat.checkSelfPermission(this,
                Manifest.permission.ACCESS_COARSE_LOCATION);
        return permissionState == PackageManager.PERMISSION_GRANTED;
    }

    private void startLocationPermissionRequest() {
        ActivityCompat.requestPermissions(MainActivity.this,
                new String[]{Manifest.permission.ACCESS_COARSE_LOCATION},
                REQUEST_PERMISSIONS_REQUEST_CODE);
    }

    private void requestPermissions() {
        boolean shouldProvideRationale =
                ActivityCompat.shouldShowRequestPermissionRationale(this,
                        Manifest.permission.ACCESS_COARSE_LOCATION);

        if (shouldProvideRationale) {
            Log.i(TAG1, "Displaying permission rationale to provide additional context.");

            showSnackbar(R.string.permission_rationale, android.R.string.ok,
                    new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {
                            // Request permission
                            startLocationPermissionRequest();
                        }
                    });

        } else {
            Log.i(TAG1, "Requesting permission");
            startLocationPermissionRequest();
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
                                           @NonNull int[] grantResults) {
        Log.i(TAG1, "onRequestPermissionResult");
        if (requestCode == REQUEST_PERMISSIONS_REQUEST_CODE) {
            if (grantResults.length <= 0) {
                Log.i(TAG1, "User interaction was cancelled.");
            } else if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                getLastLocation();
            } else {
                showSnackbar(R.string.permission_denied_explanation, R.string.settings,
                        new View.OnClickListener() {
                            @Override
                            public void onClick(View view) {
                                // Build intent that displays the App settings screen.
                                Intent intent = new Intent();
                                intent.setAction(
                                        Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
                                Uri uri = Uri.fromParts("package",
                                        BuildConfig.APPLICATION_ID, null);
                                intent.setData(uri);
                                intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                                startActivity(intent);
                            }
                        });
            }
        }
    }
}

这是我的main2activty。

package hk.android.1;

import android.annotation.SuppressLint;
import android.app.ProgressDialog;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.widget.Toast;
import android.os.Handler;
import android.support.v4.widget.SwipeRefreshLayout;
import android.util.Log;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.List;



public class Main2Activity extends AppCompatActivity {
    private static final String TAG = "Main2Activity";
    SwipeRefreshLayout mySwipeRefreshLayout;
    private static final int PAGE_SIZE = 1000;

    @SuppressLint("SetTextI18n")
    public static void main(String[] args) {
        // ...
        clearScreen();
    }

    private static void clearScreen() {
        for (int i = 0; i < PAGE_SIZE; i++) {
            System.out.println();
        }
    }

    private RecyclerView recyclerView;
    private RecyclerView.Adapter adapter;

    private List<ListItem> listItems;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        mySwipeRefreshLayout = findViewById(R.id.swiperefresh);
        mySwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener()
        {
            @Override
            public void onRefresh()
            {
                Log.i(TAG, "onRefresh called from SwipeRefreshLayout");
                myUpdateOperation();
            }
        });

        mySwipeRefreshLayout.setColorSchemeResources(android.R.color.holo_red_light,
                android.R.color.holo_blue_light,
                android.R.color.holo_green_light,
                android.R.color.holo_orange_light,
                android.R.color.holo_purple);

        recyclerView = findViewById(R.id.recyclerView);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        listItems = new ArrayList<>();

        loadRecyclerViewData();

    }

    public void loadRecyclerViewData(){
    double latitude = MainActivity.latitude;
    double longitube = MainActivity.longitube;
    String language = getResources().getString(R.string.lang);
    //String language = Locale.getDefault().getLanguage();
    private String URL_DATA = "http://xxxx/toilet/json-toilet.php?lat=" + latitude + "&lng=" + longitube + "&lang=" + language;
        final ProgressDialog progressDialog = new ProgressDialog(this);
        StringRequest stringRequest = new StringRequest(Request.Method.GET,
                URL_DATA,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String s) {
                        progressDialog.dismiss();
                        try {
                            JSONObject jsonObject = new JSONObject(s);
                            JSONArray array = jsonObject.getJSONArray("results");

                            for(int i=0; i<array.length(); i++){
                                JSONObject o = array.getJSONObject(i);
                                ListItem item;
                                item = new ListItem(
                                        o.getString("name"),
                                        o.getString("address"),
                                        o.getString("distance")
                                );
                                listItems.add(item);
                            }
                            adapter = new MyAdapter(listItems, getApplicationContext());
                            recyclerView.setAdapter(adapter);
                        }      catch (JSONException e) {
                            e.printStackTrace();

                        }
                    }
                },

                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError volleyError) {
                        progressDialog.dismiss();
                        Toast.makeText (getApplicationContext(), volleyError.getMessage(),Toast.LENGTH_LONG).show();
                    }
                });
        RequestQueue requestQueue = Volley.newRequestQueue(this);
        requestQueue.add(stringRequest);
    }


    public void openMainActivity(){
        Intent intent = new Intent(this,MainActivity.class);
        startActivity(intent);
    }

    private void myUpdateOperation()
    {
        new Handler().postDelayed(new Runnable()
                                  {
                                      @Override
                                      public void run()
                                      {
                                          mySwipeRefreshLayout.setRefreshing(false);
                                          openMainActivity();
                                      }
                                  }, 2555
        );
    }
}

我希望在将经纬度信息获取到 main2activity 并更新 URL_DATA 后可以找到最近的厕所。

Answer 1

您可以向 Intent 添加额外内容，以将数据传递到新 Activity 。

 Intent intent = new Intent(this, Main2Activity.class);
 intent.putExtra("latitude", latitude);
 intent.putExtra("longitude", longitude);
 startActivity(intent);

在您的 Main2Activity 中，您可以使用以下方法读出这些值:

Intent intent = getIntent();
double latitude = intent.getDoubleExtra("latitude", 0.0);
double latitude = intent.getDoubleExtra("longitude", 0.0);

0.0 是当您未发送 double 值时使用的默认值。您可以在 Android Documentation 中阅读有关 Intent 的更多信息。