mMap.setOnMapClickListener(this) 中的空对象错误；
Null object error in mMap.setOnMapClickListener(this);
package com.example.mukesh.airpollution;
import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.GoogleMap.OnMapClickListener;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.LatLngBounds;
import com.google.android.gms.maps.model.Polygon;
import com.google.android.gms.maps.model.PolygonOptions;
import com.google.maps.android.PolyUtil;
import java.util.List;
import java.util.ArrayList;
public class MapsActivity extends FragmentActivity
implements OnMapClickListener, OnMapReadyCallback {
//final int RQS_GooglePlayServices = 1;
private GoogleMap mMap;
//private GoogleMap googleMap;
boolean markerClicked;
PolygonOptions polygonOptions;
Polygon polygon;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
// SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
// .findFragmentById(R.id.map);
// mapFragment.getMapAsync(this);
MapFragment mapFragment = (MapFragment) getFragmentManager().findFragmentById(R.id.map);
mapFragment.getMapAsync((OnMapReadyCallback) this);
mMap.setOnMapClickListener(this);
// MapFragment mapFragment = (MapFragment) getFragmentManager().findFragmentById(R.id.map);
// mapFragment.getMapAsync(this);
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
ArrayList<Polygon> polygonList = new ArrayList<>();
Polygon polygon = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(28.555335, 76.798553), new LatLng(28.830117, 76.935883), new LatLng(28.882919, 77.080078), new LatLng(28.868489, 77.220154), new LatLng(28.714438, 77.328644), new LatLng(28.519141, 77.3698434), (new LatLng(28.399615, 77.196808)), (new LatLng(28.555335, 76.798553)))
.strokeColor(Color.RED)
// .fillColor(Color.BLUE)
//
);
// ArrayList<Polygon> polygonList = new ArrayList<>();
Polygon p1 = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(28.882919, 77.080078), new LatLng(28.752972, 77.078705), new LatLng(28.714438, 77.328644), new LatLng(28.868489, 77.220154),new LatLng(28.882919, 77.080078))
.strokeColor(Color.RED)
.fillColor(Color.BLUE));
// ArrayList<Polygon> polygonList = new ArrayList<>();
Polygon p2 = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(28.882919, 77.080078), new LatLng(28.752972, 77.078705), new LatLng(28.830117, 76.935883), new LatLng(28.882919, 77.080078))
.strokeColor(Color.RED)
//.fillColor(Color.BLUE)
);
Polygon p3 = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(28.555335, 76.798553), new LatLng(28.752972, 77.078705), new LatLng(28.830117, 76.935883), new LatLng(28.555335, 76.798553))
.strokeColor(Color.RED)
// .fillColor(Color.BLUE)
);
final LatLng SYDNEY = new LatLng(28.6139,77.2090);
final LatLng MOUNTAIN_VIEW = new LatLng(28.6387, 77.0941);
final LatLngBounds.Builder bounds;
final LatLng s=new LatLng(28.643353 ,77.446747);
bounds = new LatLngBounds.Builder();
bounds.include(new LatLng(28.643353, 77.446747));
bounds.include(new LatLng(28.509488, 76.823273));
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(SYDNEY, 10));
mMap.animateCamera(CameraUpdateFactory.zoomIn());
mMap.animateCamera(CameraUpdateFactory.zoomTo(10), 2000, null);
CameraPosition cameraPosition = new CameraPosition.Builder()
.target(MOUNTAIN_VIEW)
.zoom(10)
.bearing(90)
.tilt(30)
.build();
mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
mMap.setOnCameraChangeListener(new GoogleMap.OnCameraChangeListener() {
@Override
public void onCameraChange(CameraPosition arg0) {
// Move camera.
// googleMap.moveCamera(CameraUpdateFactory.newLatLngBounds(bounds.build(),
if (arg0.zoom >= 10) ;
else if (arg0.zoom < 9) {
CameraPosition cameraPosition1 = new CameraPosition.Builder()
.target(MOUNTAIN_VIEW) // Sets the center of the map to Mountain View
.zoom(12) // Sets the zoom
.bearing(90) // Sets the orientation of the camera to east
.tilt(30) // Sets the tilt of the camera to 30 degrees
.build(); // Creates a CameraPosition from the builder
mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition1));
}
// Remove listener to prevent position reset on camera move.
// googleMap.setOnCameraChangeListener(googleMap.moveCamera(CameraUpdateFactory.newLatLngBounds(bounds.build(),12)));
//googleMap.(latlngbounds);
}
}
);
}
@Override
public void onMapClick(LatLng point) {
Polygon polygon = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(0, 0), new LatLng(0, 5), new LatLng(3, 5), new LatLng(0, 0)));
Polygon p1 = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(0, 0), new LatLng(0, 5), new LatLng(3, 5), new LatLng(0, 0)));
Polygon p2 = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(0, 0), new LatLng(0, 5), new LatLng(3, 5), new LatLng(0, 0)));
Polygon p3 = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(0, 0), new LatLng(0, 5), new LatLng(3, 5), new LatLng(0, 0)));
//CHANGE POLYGON SPECIFICATIONS
//ADD ALL POLYGONS
List<LatLng> points = polygon.getPoints();
List<LatLng> points1 = p1.getPoints();
List<LatLng> points2 = p2.getPoints();
List<LatLng> points3 = p3.getPoints();
if (PolyUtil.containsLocation(point, points, false)) {
//Do SOMETHING...
} else if (PolyUtil.containsLocation(point, points1, false)) {
//Do SOMETHING...
}
if (PolyUtil.containsLocation(point, points2, false)) {
//Do SOMETHING...
}
if (PolyUtil.containsLocation(point, points3, false)) {
//Do SOMETHING...
}
}
}
此行出现错误
mMap.setOnMapClickListener(this);
java.lang.RuntimeException: Unable to start activity
ComponentInfo{com.example.mukesh.airpollution/com.example.mukesh.airpollution.MapsActivity}:
java.lang.NullPointerException: Attempt to invoke virtual method 'void
com.google.android.gms.maps.GoogleMap.setOnMapClickListener(com.google.android.gms.maps.GoogleMap$OnMapClickListener)'
on a null object reference
at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access0(ActivityThread.java:151)
at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual
method 'void
com.google.android.gms.maps.GoogleMap.setOnMapClickListener(com.google.android.gms.maps.GoogleMap$OnMapClickListener)'
on a null object reference
at
com.example.mukesh.airpollution.MapsActivity.onCreate(MapsActivity.java:58)
at android.app.Activity.performCreate(Activity.java:5990)
at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access0(ActivityThread.java:151)
at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
首先将setOnMapClickListener移动到onMapReady(),然后确保Map图层在所有图层中具有最高值，否则将调用最顶层的onClickListener .应该这样做。让我知道是否还有其他问题。 :)
只需删除 onMapClick 并在 onMapReady() 中实现 setonMapClickListner。现在它应该可以正常工作了。
package com.example.mukesh.airpollution;
import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.GoogleMap.OnMapClickListener;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.LatLngBounds;
import com.google.android.gms.maps.model.Polygon;
import com.google.android.gms.maps.model.PolygonOptions;
import com.google.maps.android.PolyUtil;
import java.util.List;
import java.util.ArrayList;
public class MapsActivity extends FragmentActivity
implements OnMapClickListener, OnMapReadyCallback {
//final int RQS_GooglePlayServices = 1;
private GoogleMap mMap;
//private GoogleMap googleMap;
boolean markerClicked;
PolygonOptions polygonOptions;
Polygon polygon;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
// SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
// .findFragmentById(R.id.map);
// mapFragment.getMapAsync(this);
MapFragment mapFragment = (MapFragment) getFragmentManager().findFragmentById(R.id.map);
mapFragment.getMapAsync((OnMapReadyCallback) this);
mMap.setOnMapClickListener(this);
// MapFragment mapFragment = (MapFragment) getFragmentManager().findFragmentById(R.id.map);
// mapFragment.getMapAsync(this);
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
ArrayList<Polygon> polygonList = new ArrayList<>();
Polygon polygon = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(28.555335, 76.798553), new LatLng(28.830117, 76.935883), new LatLng(28.882919, 77.080078), new LatLng(28.868489, 77.220154), new LatLng(28.714438, 77.328644), new LatLng(28.519141, 77.3698434), (new LatLng(28.399615, 77.196808)), (new LatLng(28.555335, 76.798553)))
.strokeColor(Color.RED)
// .fillColor(Color.BLUE)
//
);
// ArrayList<Polygon> polygonList = new ArrayList<>();
Polygon p1 = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(28.882919, 77.080078), new LatLng(28.752972, 77.078705), new LatLng(28.714438, 77.328644), new LatLng(28.868489, 77.220154),new LatLng(28.882919, 77.080078))
.strokeColor(Color.RED)
.fillColor(Color.BLUE));
// ArrayList<Polygon> polygonList = new ArrayList<>();
Polygon p2 = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(28.882919, 77.080078), new LatLng(28.752972, 77.078705), new LatLng(28.830117, 76.935883), new LatLng(28.882919, 77.080078))
.strokeColor(Color.RED)
//.fillColor(Color.BLUE)
);
Polygon p3 = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(28.555335, 76.798553), new LatLng(28.752972, 77.078705), new LatLng(28.830117, 76.935883), new LatLng(28.555335, 76.798553))
.strokeColor(Color.RED)
// .fillColor(Color.BLUE)
);
final LatLng SYDNEY = new LatLng(28.6139,77.2090);
final LatLng MOUNTAIN_VIEW = new LatLng(28.6387, 77.0941);
final LatLngBounds.Builder bounds;
final LatLng s=new LatLng(28.643353 ,77.446747);
bounds = new LatLngBounds.Builder();
bounds.include(new LatLng(28.643353, 77.446747));
bounds.include(new LatLng(28.509488, 76.823273));
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(SYDNEY, 10));
mMap.animateCamera(CameraUpdateFactory.zoomIn());
mMap.animateCamera(CameraUpdateFactory.zoomTo(10), 2000, null);
CameraPosition cameraPosition = new CameraPosition.Builder()
.target(MOUNTAIN_VIEW)
.zoom(10)
.bearing(90)
.tilt(30)
.build();
mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
mMap.setOnCameraChangeListener(new GoogleMap.OnCameraChangeListener() {
@Override
public void onCameraChange(CameraPosition arg0) {
// Move camera.
// googleMap.moveCamera(CameraUpdateFactory.newLatLngBounds(bounds.build(),
if (arg0.zoom >= 10) ;
else if (arg0.zoom < 9) {
CameraPosition cameraPosition1 = new CameraPosition.Builder()
.target(MOUNTAIN_VIEW) // Sets the center of the map to Mountain View
.zoom(12) // Sets the zoom
.bearing(90) // Sets the orientation of the camera to east
.tilt(30) // Sets the tilt of the camera to 30 degrees
.build(); // Creates a CameraPosition from the builder
mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition1));
}
// Remove listener to prevent position reset on camera move.
// googleMap.setOnCameraChangeListener(googleMap.moveCamera(CameraUpdateFactory.newLatLngBounds(bounds.build(),12)));
//googleMap.(latlngbounds);
}
}
);
}
@Override
public void onMapClick(LatLng point) {
Polygon polygon = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(0, 0), new LatLng(0, 5), new LatLng(3, 5), new LatLng(0, 0)));
Polygon p1 = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(0, 0), new LatLng(0, 5), new LatLng(3, 5), new LatLng(0, 0)));
Polygon p2 = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(0, 0), new LatLng(0, 5), new LatLng(3, 5), new LatLng(0, 0)));
Polygon p3 = mMap.addPolygon(new PolygonOptions()
.add(new LatLng(0, 0), new LatLng(0, 5), new LatLng(3, 5), new LatLng(0, 0)));
//CHANGE POLYGON SPECIFICATIONS
//ADD ALL POLYGONS
List<LatLng> points = polygon.getPoints();
List<LatLng> points1 = p1.getPoints();
List<LatLng> points2 = p2.getPoints();
List<LatLng> points3 = p3.getPoints();
if (PolyUtil.containsLocation(point, points, false)) {
//Do SOMETHING...
} else if (PolyUtil.containsLocation(point, points1, false)) {
//Do SOMETHING...
}
if (PolyUtil.containsLocation(point, points2, false)) {
//Do SOMETHING...
}
if (PolyUtil.containsLocation(point, points3, false)) {
//Do SOMETHING...
}
}
}
此行出现错误
mMap.setOnMapClickListener(this);
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mukesh.airpollution/com.example.mukesh.airpollution.MapsActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.maps.GoogleMap.setOnMapClickListener(com.google.android.gms.maps.GoogleMap$OnMapClickListener)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) at android.app.ActivityThread.access0(ActivityThread.java:151) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5254) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.maps.GoogleMap.setOnMapClickListener(com.google.android.gms.maps.GoogleMap$OnMapClickListener)' on a null object reference at com.example.mukesh.airpollution.MapsActivity.onCreate(MapsActivity.java:58) at android.app.Activity.performCreate(Activity.java:5990) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) at android.app.ActivityThread.access0(ActivityThread.java:151) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5254) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
首先将setOnMapClickListener移动到onMapReady(),然后确保Map图层在所有图层中具有最高值，否则将调用最顶层的onClickListener .应该这样做。让我知道是否还有其他问题。 :)
只需删除 onMapClick 并在 onMapReady() 中实现 setonMapClickListner。现在它应该可以正常工作了。