【发布时间】：2017-11-13 20:47:09
【问题描述】：
在我的情况下，应用程序总是崩溃原因：java.lang.NullPointerException：尝试调用虚拟方法'com.google.android.gms.maps.model.Polyline com.google.android.gms.maps.GoogleMap。 addPolyline 和我写下面的代码，但是运行时显示强制关闭错误
ActivityMain
public class MainActivity extends FragmentActivity implements OnMapReadyCallback {
//Google Maps
public GoogleMap mMap;
//
SQLHelper dbHelper;
Cursor cursor;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//DB
dbHelper = new SQLHelper(this);
try {
dbHelper.createDataBase();
}
catch (Exception ioe) {
Toast.makeText(getApplicationContext(), "Gagal", Toast.LENGTH_LONG).show();
}
//BUAT MAP
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.peta);
mapFragment.getMapAsync(this);
int simpul_awal = 0;
int simpul_tujuan = 3;
//output algoritma
dijkstra algo = new dijkstra();
algo.jalurTerpendek(this, simpul_awal, simpul_tujuan);
Toast.makeText(getBaseContext(), "Jalur terdekat : "+algo.jalur_terpendek1, Toast.LENGTH_LONG).show();
String[] exp = algo.jalur_terpendek1.split("->");
int start = 0;
//Query DB; Gambar Jalurnya!
dbHelper = new SQLHelper(this);
SQLiteDatabase db = dbHelper.getReadableDatabase();
for(int i = 0; i < exp.length-1; i++){
ArrayList<LatLng> lat_lng = new ArrayList<LatLng>();
cursor = db.rawQuery("SELECT jalur FROM graph where simpul_awal ="+exp[start]+" and simpul_tujuan ="+exp[(++start)], null);
cursor.moveToFirst();
int idx_koord = 0;
String[] exp_koord = cursor.getString(0).split(",");
for(int j = 0; j < exp_koord.length/2; j++){
lat_lng.add( new LatLng(Double.parseDouble(exp_koord[idx_koord]), Double.parseDouble(exp_koord[++idx_koord])) );
++idx_koord;
}
PolylineOptions jalurBiasa = new PolylineOptions();
jalurBiasa.addAll(lat_lng).width(5).color(0xff4b9efa).geodesic(true);
**mMap**.addPolyline(jalurBiasa);
}
//zoom ke koordinat
cursor = db.rawQuery("SELECT jalur FROM graph where simpul_awal ="+exp[0]+" and simpul_tujuan ="+exp[1], null);
cursor.moveToFirst();
String[] koord = cursor.getString(0).split(",");
**mMap**.moveCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(Double.parseDouble(koord[0]), Double.parseDouble(koord[1])), 12));
}//oncreate
@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));
}
}
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="kokoro1.com.kokoro1">
<!--
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.
-->
<uses-permission android:name="kokoro1.com.kokoro1.MAPS_RECEIVE"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<!--
The API key for Google Maps-based APIs is defined as a string resource.
(See the file "res/values/google_maps_api.xml").
Note that the API key is linked to the encryption key used to sign the APK.
You need a different API key for each encryption key, including the release key that is used to
sign the APK for publishing.
You can define the keys for the debug and release targets in src/debug/ and src/release/.
-->
<meta-data
android:name="com.google.android.geo.API_KEY"
android:value="AIzaSyAIbPBUmnZ1TF0rHkGjLN-g1GNYHsnR5Uo" />
<activity
android:name=".MainActivity"
android:label="@string/title_activity_main">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
MyLogcat
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
Process: kokoro1.com.kokoro1, PID: 26867
java.lang.RuntimeException: Unable to start activity ComponentInfo{kokoro1.com.kokoro1/kokoro1.com.kokoro1.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.maps.model.Polyline com.google.android.gms.maps.GoogleMap.addPolyline(com.google.android.gms.maps.model.PolylineOptions)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2442)
at android.app.ActivityThread.access$800(ActivityThread.java:156)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1351)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:211)
at android.app.ActivityThread.main(ActivityThread.java:5389)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1020)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:815)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.maps.model.Polyline com.google.android.gms.maps.GoogleMap.addPolyline(com.google.android.gms.maps.model.PolylineOptions)' on a null object reference
at kokoro1.com.kokoro1.MainActivity.onCreate(MainActivity.java:80)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2332)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2442)
at android.app.ActivityThread.access$800(ActivityThread.java:156)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1351)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:211)
at android.app.ActivityThread.main(ActivityThread.java:5389)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1020)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:815)
Application terminated.
【问题讨论】：
标签： android google-maps