如何使用GPS坐标更新TextView

Question

我是Android和Java开发的新手，所以请耐心等待：(我正在尝试获取手机的GPS坐标，然后用纬度更新TextView(我现在只需要纬度(。到目前为止，我拥有的是：

main.xml:
[...]
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Get my location"
        android:id="@+id/button2"
        android:layout_gravity="center_horizontal"
        android:onClick="returnMyCoordinates" />
<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceMedium"
    android:text="This is where the lat value will show up"
    android:id="@+id/latitudeResult" />
MapsActivity.java:
        public void returnMyCoordinates(View v, Location location){
        double latiTude;
        latiTude = location.getLatitude();
        String lat_value;
        lat_value = Double.toString(latiTude);
        TextView latView = (TextView) findViewById(R.id.latitudeResult);
        latView.setText(lat_value);
    }

我的理解是，我不能将"View v"与方法声明中的其他参数组合在一起。如果这是真的，那为什么呢？否则我怎么能做到这一点呢？

以下是整个上下文文件：

package com.example.googlemapsandroidapi;
import android.content.Context;
import android.content.pm.PackageManager;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.maps.CameraUpdateFactory;
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.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback,LocationListener{
    private GoogleMap mMap = null;
    protected LocationManager locationManager;
    Double lat;
    Double long1;
    TextView txtLat;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }
        public void returnMyCoordinates(View v, Location location){
        double latiTude;
        latiTude = location.getLatitude();
        String lat_value;
        lat_value = Double.toString(latiTude);
        TextView latView = (TextView) findViewById(R.id.latitudeResult);
        latView.setText(lat_value);
    }

     public void showLocation(View v) {
     setContentView(R.layout.activity_maps);
     SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
     .findFragmentById(R.id.map);
     mapFragment.getMapAsync(MapsActivity.this);
     ActivityCompat.requestPermissions(MapsActivity.this,
     new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION},
     1);
     locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
     try {
     locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 250000, 0, this);
     locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 250000, 0, this);
     if(mMap!=null){
     mMap.setMyLocationEnabled(true);
     }
     Log.e("TAG","Location Manager Called Successfully.");
     }catch (SecurityException e){
     e.printStackTrace();
     Log.e("TAG","SecurityException:"+e.getMessage());
     }
     }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode) {
            case 1:
                if (grantResults.length > 0
                        && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    try {
                        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 250000, 0, MapsActivity.this);
                        locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 250000, 0, MapsActivity.this);
                        if(mMap!=null){
                            mMap.setMyLocationEnabled(true);
                        }
                        Log.e("TAG","Location Manager Called Successfully.");
                    }catch (SecurityException e){
                        e.printStackTrace();
                        Log.e("TAG","SecurityException:"+e.getMessage());
                    }
                } else {
                    Toast.makeText(MapsActivity.this,"Sorry We Need All Permissions Open App Again and Allow All.",Toast.LENGTH_LONG).show();
                    MapsActivity.this.finish();
                }
                return;
        }
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;
        // Add a marker in Sydney and move the camera
        /*LatLng sydney = new LatLng(-34, 151);
        mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));*/
    }

    @Override
    public void onStatusChanged(String s, int i, Bundle bundle) {
    }
    @Override
    public void onProviderEnabled(String s) {
    }
    @Override
    public void onProviderDisabled(String s) {
    }
}

Answer 1

尝试在onCreate方法中初始化TextView latView = (TextView) findViewById(R.id.latitudeResult);，因为我认为您的MapsActivity.java是一个Activity？你能把整个MapActivity.java发出来吗。

Answer 2

请使用所有类尝试此操作。MainActivity.class:

public class MainActivity extends Activity implements
    ConnectionCallbacks, OnConnectionFailedListener, View.OnClickListener {

protected GoogleApiClient mGoogleApiClient;
protected Location location;
protected boolean mAddressRequested;
protected String mAddressOutput;
private AddressResultReceiver mResultReceiver;
ProgressBar mProgressBar;
private Button btnCurrentLocation, btnShowAddress;
private TextView tvSetLat, tvSetLang, tvAddress;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    setId();
    setListener();
    mProgressBar = (ProgressBar) findViewById(R.id.progress_bar);

    updateValuesFromBundle(savedInstanceState);
    buildGoogleApiClient();
}

private void setId() {
    tvSetLat = (TextView) findViewById(R.id.tvSetLat);
    tvSetLang = (TextView) findViewById(R.id.tvSetLang);
    btnCurrentLocation = (Button) findViewById(R.id.btnCurrentLocation);

}

private void setListener() {
    btnCurrentLocation.setOnClickListener(this);

}
private void updateValuesFromBundle(Bundle savedInstanceState) {
}
protected synchronized void buildGoogleApiClient() {
    mGoogleApiClient = new GoogleApiClient.Builder(this)
            .addConnectionCallbacks(this)
            .addOnConnectionFailedListener(this)
            .addApi(LocationServices.API)
            .build();
}

@Override
protected void onStart() {
    super.onStart();
    mGoogleApiClient.connect();
}
@Override
protected void onStop() {
    super.onStop();
    if (mGoogleApiClient.isConnected()) {
        mGoogleApiClient.disconnect();
    }
}
@Override
public void onConnected(Bundle connectionHint) {
    if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return;
    }
    location = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
    if (location != null) {
        if (!Geocoder.isPresent()) {
            Toast.makeText(this, R.string.no_geocoder_available, Toast.LENGTH_LONG).show();
            return;
        }
        if (mAddressRequested) {
            startIntentService();
        }
    }
}

@Override
public void onConnectionFailed(ConnectionResult result) {
    Log.i(TAG, "Connection failed: ConnectionResult.getErrorCode() = " + result.getErrorCode());
}

@Override
public void onConnectionSuspended(int cause) {
    Log.i(TAG, "Connection suspended");
    mGoogleApiClient.connect();
}

protected void showToast(String text) {
    Toast.makeText(this, text, Toast.LENGTH_SHORT).show();
}
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    savedInstanceState.putBoolean(ADDRESS_REQUESTED_KEY, mAddressRequested);
    savedInstanceState.putString(LOCATION_ADDRESS_KEY, mAddressOutput);
    super.onSaveInstanceState(savedInstanceState);
}

@Override
public void onClick(View view) {
    switch (view.getId()) {
        case R.id.btnCurrentLocation:
            if (location != null) {
                tvSetLat.setText(String.valueOf(location.getLatitude()));
                tvSetLang.setText(String.valueOf(location.getLongitude()));
            }
            break;

        default:
            break;
    }
}

}

您的xml是activity_main

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.example.android.geocoderdemo.MainActivity">
<ProgressBar
    android:id="@+id/progress_bar"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true" />
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:weightSum="1">
    <TextView
        android:id="@+id/tvSetLat"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight=".50"
        android:padding="10dp"
        android:text="set lat" />
    <TextView
        android:id="@+id/tvSetLang"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight=".50"
        android:padding="10dp"
        android:text="set long" />
</LinearLayout>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:weightSum="1">

    <Button
        android:id="@+id/btnCurrentLocation"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight=".50"
        android:gravity="center"
        android:text="Get Current Location" />
</LinearLayout>

并在menifest:中添加权限

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

同时在gradle中添加播放服务。

compile 'com.google.android.gms:play-services:9.4.0'

你可以看到我的应用程序gradle。

apply plugin: 'com.android.application'

android{compileSdk版本24buildToolsVersion"24.0.1">

defaultConfig {
    applicationId "com.example.android.geocoderdemo"
    minSdkVersion 15
    targetSdkVersion 24
    versionCode 1
    versionName "1.0"
    multiDexEnabled true
}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}

}

依赖项{compile fileTree(包括：['*.jar']，dir:'libs'(testCompile'junit:junit:4.12'编译"com.android.support:multex:1.0.0"编译"com.android.support:appcompat-v7:24.1.1'编译"com.google.android.gms:play services:9.4.0'"}