android - 在单击按钮时查找当前位置时应用程序崩溃

Question

我的问题是应用程序运行时。 onClick 函数应该通过经度、纬度从 GPS 调用我的位置。但问题是单击按钮时应用程序崩溃。解决方案是什么？我尝试按照旧堆栈问题的说明进行操作，但错误仍然存​​在。

这是调试消息:

-------------------------------------------------- -------------------------------------------------- -------------------------------------------

java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.maps.GoogleMap.animateCamera(com.google.android.gms.maps.CameraUpdate)' on a null object reference at com.booleandev.googlfind.MainActivity.onClick(MainActivity.java:97)

-------------------------------------------------- -------------------------------------------------- -------------------------------------------

public void onClick(View v) {
        if (v == koordinat) {

            if (latitude != 0 && longitude != 0) {
                Toast.makeText(getApplicationContext(), "Latitude : " + latitude + " Longitude : " + longitude, Toast.LENGTH_LONG).show();
            }

        }

     if (v == posisi_user) {


          LatLng user = new LatLng(latitude, longitude);

        googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(
                user, 12));

     }
    }

这是我完整的 MainActivity.java

package com.booleandev.googlfind;

import android.*;
import android.Manifest;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Build;
import android.os.Bundle;
import android.provider.Settings;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import com.google.android.gms.maps.MapView;
import com.google.android.gms.maps.CameraUpdate;
import com.google.android.gms.maps.GoogleMap.OnMapClickListener;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
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.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class MainActivity extends FragmentActivity implements LocationListener, OnMapReadyCallback,View.OnClickListener {

    GoogleMap googleMap;
    double latitude;
    double longitude;
    Button koordinat;
    Button posisi_user;
    private final static int MY_PERMISSION_FINE_LOCATION = 101;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        koordinat = (Button) findViewById(R.id.koordinat);
        posisi_user = (Button) findViewById(R.id.posisi_user);

        koordinat.setOnClickListener(this);
        posisi_user.setOnClickListener(this);

        SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        fm.getMapAsync(this);

        CekGPS();


        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
//            googleMap.setMyLocationEnabled(true);

        } else {

            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, MY_PERMISSION_FINE_LOCATION);
            }
        }

        if (latitude != 0 && longitude != 0) {
            Toast.makeText(getApplicationContext(), "Latitude : " + latitude + " Longitude : " + longitude, Toast.LENGTH_LONG).show();
        }
    }



    @Override
    public void onClick(View v) {
        if (v == koordinat) {

            if (latitude != 0 && longitude != 0) {
                Toast.makeText(getApplicationContext(), "Latitude : " + latitude + " Longitude : " + longitude, Toast.LENGTH_LONG).show();
            }

        }

     if (v == posisi_user) {


           LatLng user = new LatLng(latitude, longitude);

        googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(
                user, 12));


     }
    }


    public void CekGPS() {
        try {

                /* pengecekan GPS hidup / tidak */
            LocationManager manager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

            if (!manager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {

                AlertDialog.Builder builder = new AlertDialog.Builder(this);
                builder.setTitle("Info");
                builder.setMessage("Anda akan mengaktifkan GPS?");

                builder.setPositiveButton("Ya",
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog,
                                                int which) {

                                Intent i = new Intent(
                                        Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                                startActivity(i);
                            }
                        });

                builder.setNegativeButton("Tidak",
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog,
                                                int which) {

                                dialog.dismiss();
                            }
                        });
                builder.create().show();

            }

        } catch (Exception e) {

        }

        int status = GooglePlayServicesUtil
                .isGooglePlayServicesAvailable(getBaseContext());

        // menampilkan status google play service
        if (status != ConnectionResult.SUCCESS) {
            int requestCode = 10;
            Dialog dialog = GooglePlayServicesUtil.getErrorDialog(status, this,
                    requestCode);
            dialog.show();

        } else {
            // Google Play Services tersedia

            try {
                LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

                // Membuat kriteria untuk penampungan provider
                Criteria criteria = new Criteria();

                // Mencari provider terbaik
                String provider = locationManager.getBestProvider(criteria,
                        true);

                // Mendapatkan lokasi terakhir
                Location location = locationManager.getLastKnownLocation(provider);

                if (location != null) {
                    onLocationChanged(location);
                }
                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) {
                    // TODO: Consider calling
                    //    ActivityCompat#requestPermissions
                    // here to request the missing permissions, and then overriding
                    //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                    //                                          int[] grantResults)
                    // to handle the case where the user grants the permission. See the documentation
                    // for ActivityCompat#requestPermissions for more details.
                    return;
                }
                locationManager.requestLocationUpdates(provider, 5000, 0, this);
            } catch (Exception e) {


            }
        }
    }

    @Override
    public void onLocationChanged(Location lokasi) {
        // TODO Auto-generated method stub
        latitude =lokasi.getLatitude();
        longitude = lokasi.getLongitude();
    }

    @Override
    public void onProviderDisabled(String provider) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onProviderEnabled(String provider) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub

    }

    public void onMapReady(GoogleMap googleMap) {
        googleMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
        googleMap.setTrafficEnabled(true);
        googleMap.setIndoorEnabled(true);
        googleMap.setBuildingsEnabled(true);
        googleMap.getUiSettings().setZoomControlsEnabled(true);
    }


    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode) {
            case MY_PERMISSION_FINE_LOCATION:
                if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != 
PackageManager.PERMISSION_GRANTED) {
                        googleMap.setMyLocationEnabled(true);
                    }

                }
                else {
                    Toast.makeText(getApplicationContext(), "GPS TURN OFF", Toast.LENGTH_SHORT).show();
                    finish();
                }
                break;
        }
    }
}

我的 activity_main.xml 也是

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/home_root"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:weightSum="10"
    >


    <fragment

        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="9"
        android:name="com.google.android.gms.maps.SupportMapFragment"
        class="com.google.android.gms.maps.SupportMapFragment"
        />

    <LinearLayout

        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:orientation="horizontal">
        <Button
            android:id="@+id/koordinat"
            style="?android:attr/borderlessButtonStyle"
            android:textStyle="bold"
            android:layout_height="wrap_content"
            android:text="Koordinat User"
            android:layout_weight="1"
            android:layout_width="0dp" />
        <Button
            style="?android:attr/borderlessButtonStyle"
            android:id="@+id/posisi_user"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Posisi User"/>

    </LinearLayout>


</LinearLayout>

list

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="">

    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
    <uses-permission android:name="com.google.android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="com.google.android.permission.ACCESS_COARSE_LOCATION" />

    <!--
         The ACCESS_COARSE/FINE_LOCATION permissions are not required to use
         Google Maps Android API v2, but you must specify either coarse or fine
         location permissions for the 'MyLocation' functionality. 
    -->


    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <meta-data
            android:name="com.google.android.maps.v2.API_KEY"
            android:value="Secret" />
        <meta-data
            android:name="com.google.android.gms.version"
            android:value="@integer/google_play_services_version" />
        <activity android:name=".lokasi">

        </activity>
        <activity android:name=".spalsh">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>




    </application>

</manifest>

Answer 1

您尚未在 map 就绪时初始化 googlemap 变量
点赞this.googleMap=googleMap;

  public void onMapReady(GoogleMap googleMap) {
        this.googleMap=googleMap;
        googleMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
        googleMap.setTrafficEnabled(true);
        googleMap.setIndoorEnabled(true);
        googleMap.setBuildingsEnabled(true);
        googleMap.getUiSettings().setZoomControlsEnabled(true);
    }

试试这个