无法启动 activity java.lang.NullPointerException

Unable to start activity java.lang.NullPointerException

我正在尝试在我的应用程序中使用 google 地图。我已经添加了库和所有需要的东西,但应用程序以 NULL 指针异常终止。请建议我。提前谢谢你。

Logcat

E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.yd.hhivaction/com.yd.hhivacation.MapIt}: java.lang.NullPointerException
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2097)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2122)
        at android.app.ActivityThread.access0(ActivityThread.java:140)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1228)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4895)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.NullPointerException
        at com.yd.hhivacation.MapIt.onCreate(MapIt.java:56)
        at android.app.Activity.performCreate(Activity.java:5163)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2061)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2122)
            at android.app.ActivityThread.access0(ActivityThread.java:140)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1228)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4895)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
            at dalvik.system.NativeStart.main(Native Method)

MapIt.java

package com.yd.hhivacation;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.Intent;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;

import com.android.volley.Request.Method;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.VolleyLog;
import com.android.volley.toolbox.JsonObjectRequest;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.location.LocationListener;
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.Marker;
import com.google.android.gms.maps.model.MarkerOptions;

public class MapIt extends ActionBarActivity implements LocationListener,
        OnMapReadyCallback, android.location.LocationListener {

    GoogleMap googlemap;
    String listingid;
    JSONArray data;
    String laitude;
    String logitude;
    String headline, subline;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_map_it);
        Intent in = getIntent();
        listingid = in.getStringExtra("listingid");

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

        googlemap = mapFragment.getMap();
        googlemap.setMyLocationEnabled(true);
        LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
        Criteria criteria = new Criteria();
        String bestProvider = locationManager.getBestProvider(criteria, true);
        Location location = locationManager.getLastKnownLocation(bestProvider);
        if (location != null) {
            onLocationChanged(location);
        }
        locationManager.requestLocationUpdates(bestProvider, 20000, 0, this);
    }

    /**
     * This is where we can add markers or lines, add listeners or move the
     * camera. In this case, we just add a marker near Africa.
     */
    @Override
    public void onMapReady(final GoogleMap map) {

        String url2 = "http://m.hhivacation.com/webapi/getmapdetailsbyID.php?listingid="
                + listingid;
        JsonObjectRequest jsonObjReq = new JsonObjectRequest(Method.GET, url2,
                null, new Response.Listener<JSONObject>() {

                    @SuppressLint("NewApi")
                    Context context;

                    @SuppressLint("UseValueOf")
                    @Override
                    public void onResponse(JSONObject response) {

                        try {
                            boolean suc = Boolean.parseBoolean(response
                                    .getString("success"));

                            if (suc = true) {

                                data = response.getJSONArray("listing_details");

                                JSONObject feedObj = (JSONObject) data.get(0);

                                headline = feedObj.getString("headline");
                                subline = feedObj.getString("subline");

                                laitude = feedObj.getString("map_lat");
                                logitude = feedObj.getString("map_long");

                                if (laitude.length() != 0
                                        & laitude.length() != 0) {
                                    double lo, la;

                                    try {

                                        lo = new Double(logitude);
                                        la = new Double(laitude);

                                    } catch (NumberFormatException e) {
                                        lo = 75.8655; // your default value

                                        la = 22.7253;
                                    }
                                    final LatLng PERTH = new LatLng(la, lo);
//                                  Marker perth = map
//                                          .addMarker(new MarkerOptions()
//                                                  .position(PERTH)
//                                                  .title(headline)
//                                                  .snippet(subline));
//
//                                  map.getUiSettings().setZoomControlsEnabled(
//                                          false);
//
//                                  map.moveCamera(CameraUpdateFactory.newLatLngZoom(
//                                          new LatLng(
//                                                  Double.parseDouble(laitude),
//                                                  Double.parseDouble(logitude)),
//                                          4));
                                }

                                Log.d("mapit", headline + "&" + subline);

                            }

                        } catch (JSONException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }

                        Log.d("resonce", laitude + "--" + logitude);
                        /*
                         * responseText.setText("Response:" + " " +
                         * response.toString() + ":" + st1);
                         */

                    }
                }, new Response.ErrorListener() {

                    @Override
                    public void onErrorResponse(VolleyError error) {
                        VolleyLog.d("App", "Error: " + error.getMessage());
                        // hide the progress dialog

                    }
                });

        VolleySingleton.getInstance(getApplicationContext()).addToRequestQueue(
                jsonObjReq);

    }

    @SuppressLint("UseValueOf")
    @Override
    public void onLocationChanged(Location location) {
        // TODO Auto-generated method stub

        if (laitude != null && logitude != null) {

            if (laitude.length() != 0 & logitude.length() != 0) {

                double lo, la;

                try {

                    lo = new Double(logitude);
                    la = new Double(laitude);

                } catch (NumberFormatException e) {
                    la = 42.3482; // your default value

                    lo = 75.1890;
                }
                double latitude = lo;
                double longitude = la;
                LatLng latLng = new LatLng(latitude, longitude);
                googlemap.addMarker(new MarkerOptions().position(latLng));
                googlemap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
                googlemap.animateCamera(CameraUpdateFactory.zoomTo(6));

//              Toast.makeText(MapIt.this, location + " & " + longitude,
//                      Toast.LENGTH_SHORT).show();
            }
        }
    }

    private boolean isGooglePlayServicesAvailable() {
        int status = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
        if (ConnectionResult.SUCCESS == status) {
            return true;
        } else {
            GooglePlayServicesUtil.getErrorDialog(status, this, 0).show();
            return false;
        }
    }

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

    }

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

    }

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

    }

}

清单

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

    android:versionCode="2"
    android:versionName="1.1" >

    <uses-sdk
        android:minSdkVersion="11"
        android:targetSdkVersion="19" />

    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <!-- External storage for caching. -->
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <!-- My Location -->
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.CALL_PHONE" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />

    <!-- Maps API needs OpenGL ES 2.0. -->
    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true" />

    <application
        android:name="com.yd.hhivacation.MyApplication"
        android:allowBackup="true"
        android:icon="@drawable/icon"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <meta-data
            android:name="com.google.android.maps.v2.API_KEY"
            android:value="AIzaSyCNe5t_yjE_NwwWTNj8MYq2oJNetFfFIk4" />
        <meta-data
            android:name="com.google.android.gms.version"
            android:value="@integer/google_play_services_version" />

        <activity
            android:name="com.yd.hhivacation.FirstActivity"
            android:label="@string/app_name"
            android:screenOrientation="portrait"
            android:windowSoftInputMode="stateHidden" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

        <activity
            android:name=".SubCat"
            android:label="@string/title_activity_sub_cat"
            android:screenOrientation="portrait"
            android:windowSoftInputMode="stateHidden" >
        </activity>
        <activity
            android:name=".Listing"
            android:label="@string/title_activity_listing"
            android:screenOrientation="portrait"
            android:windowSoftInputMode="stateHidden" >
        </activity>
        <activity
            android:name=".Detail"
            android:label="@string/title_activity_detail"
            android:screenOrientation="portrait"
            android:windowSoftInputMode="stateHidden" >
        </activity>
        <activity
            android:name=".WriteReview"
            android:label="@string/title_activity_write_review"
            android:screenOrientation="portrait"
            android:windowSoftInputMode="stateHidden" >
        </activity>
        <activity
            android:name=".MapIt"
            android:label="@string/title_activity_map_it"
            android:screenOrientation="portrait" >
        </activity>
        <activity
            android:name=".Search"
            android:label="@string/title_activity_search"
            android:screenOrientation="portrait"
            android:windowSoftInputMode="stateHidden" >
        </activity>
        <activity
            android:name=".F_about"
            android:label="@string/title_activity_f_about"
            android:screenOrientation="portrait"
            android:windowSoftInputMode="stateHidden" >
        </activity>
        <activity
            android:name=".F_feedback"
            android:label="@string/title_activity_f_feedback"
            android:screenOrientation="portrait"
            android:windowSoftInputMode="stateHidden" >
        </activity>
        <activity
            android:name=".F_public"
            android:label="@string/title_activity_f_public"
            android:screenOrientation="portrait"
            android:windowSoftInputMode="stateHidden" >
        </activity>
        <activity
            android:name=".F_advert"
            android:label="@string/title_activity_f_advert"
            android:screenOrientation="portrait"
            android:windowSoftInputMode="stateHidden" >
        </activity>
        <activity
            android:name=".Loadreviews"
            android:label="@string/title_activity_loadreviews"
            android:screenOrientation="portrait"
            android:windowSoftInputMode="stateHidden" >
        </activity>
        <activity
            android:name=".Websites"
            android:label="@string/title_activity_websites"
            android:screenOrientation="portrait"
            android:windowSoftInputMode="stateHidden" >
        </activity>

    </application>

</manifest>

activity_map_it

<fragment xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/map"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  class="com.google.android.gms.maps.SupportMapFragment"/>

新 Logcat 几处改动后

E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.yd.hhivaction/com.yd.hhivacation.MapIt}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2097)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2122)
            at android.app.ActivityThread.access0(ActivityThread.java:140)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1228)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4895)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.yd.hhivacation.MapIt.onCreate(MapIt.java:52)
            at android.app.Activity.performCreate(Activity.java:5163)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2061)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2122)
            at android.app.ActivityThread.access0(ActivityThread.java:140)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1228)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4895)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
            at dalvik.system.NativeStart.main(Native Method)

@52 googlemap.setMyLocationEnabled(真);

错误可能在第 googlemap = mapFragment.getMap(); 行。在上一行中,您使用:mapFragment.getMapAsync(this);,在 onMapReady 中,您应该像 googlemap = map 一样存储 google 映射。所以你需要做的是:

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_map_it);
        Intent in = getIntent();
        listingid = in.getStringExtra("listingid");

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

        LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
        Criteria criteria = new Criteria();
        String bestProvider = locationManager.getBestProvider(criteria, true);
        Location location = locationManager.getLastKnownLocation(bestProvider);
        if (location != null) {
            onLocationChanged(location);
        }
        locationManager.requestLocationUpdates(bestProvider, 20000, 0, this);
    }


@Override
    public void onMapReady(final GoogleMap map) {
        if (this.googlemap == null) {
            googlemap = map;
            googlemap.setMyLocationEnabled(true);
        }
        String url2 = "http://m.hhivacation.com/webapi/getmapdetailsbyID.php?listingid="
                + listingid;
     ....
     ....
    }

也在onLocationChanged

if (googlemap != null) {
    googlemap.addMarker(new MarkerOptions().position(latLng));
    googlemap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
    googlemap.animateCamera(CameraUpdateFactory.zoomTo(6));
}

希望对您有所帮助。