java - Android Studio 监听器导致错误

Question

我正在尝试实现一个监听器来监视对标记的所有点击(Google Maps API)，以允许在标记点击事件触发器上调用函数。但是，每次我包含事件监听器代码时，应用程序都会崩溃。

事件监听器 - setOnMarkerClickListener

如何正确实现此监听器并处理崩溃？

我已经使用的代码是:

mMap.setOnMarkerClickListener(new GoogleMap.OnMarkerClickListener() {
            @Override
            public boolean onMarkerClick(Marker marker) {

                // TODO Auto-generated method stub
                if(marker.equals(ibrox)){
                    Log.w("Click", "test");
                    return true;
                }
                return false;

            }
        });

我希望程序能够运行而不会崩溃，并且函数能够记录“测试”。

编辑:ibrox 变量的值 -

private static final LatLng ibrox = new LatLng(55.8522161, -4.3138359);

整个代码:

package com.example.googlemaps;

import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.util.Log;
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.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

    private GoogleMap mMap;

    private static final LatLng ibrox = new LatLng(55.8522161, -4.3138359);
    private Marker mIbrox;

    @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);

        mMap.setOnMarkerClickListener(new GoogleMap.OnMarkerClickListener() {
            @Override
            public boolean onMarkerClick(Marker marker) {

                // TODO Auto-generated method stub
                if(marker.equals(ibrox)){
                    Log.w("Click", "test");
                    return true;
                }
                return false;

            }
        });

    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;

        // Add a marker in Sydney and move the camera
        LatLng sydney = new LatLng(40.7589, -73.9851);
        mIbrox = mMap.addMarker(new MarkerOptions()
                .position(ibrox)
                .title("Ibrox"));

        mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in a place"));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
    }
}

Answer 1

请确保mMap不为空。您需要在 onMapReady 方法中设置监听器。

按照这个例子:- https://github.com/googlemaps/android-samples/blob/master/ApiDemos/java/app/src/main/java/com/example/mapdemo/MarkerDemoActivity.java

@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;
    mMap.setOnMarkerClickListener(new GoogleMap.OnMarkerClickListener() {
            @Override
            public boolean onMarkerClick(Marker marker) {

                // TODO Auto-generated method stub
                if(marker.equals(ibrox)){
                    Log.w("Click", "test");
                    return true;
                }
                return false;

            }
        });
        // Add a marker in Sydney and move the camera
        LatLng sydney = new LatLng(40.7589, -73.9851);
        mIbrox = mMap.addMarker(new MarkerOptions()
                .position(ibrox)
                .title("Ibrox"));

        mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in a place"));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
    }