Question

在发布这个问题之前，我已经搜索了很多所以它接缝就像我无法使用MapsActivity显示地图 - 我正在使用Kotlin -
所以这是我的代码

package com.example.digit.findmyphone

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
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.MarkerOptions
import com.google.firebase.database.*
import java.util.HashMap  
class MapsActivity : AppCompatActivity(), OnMapReadyCallback {

    private lateinit var mMap: GoogleMap

    var myRef:DatabaseReference?=null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_maps)

        val bundle = intent.extras
        val phoneNumber = bundle.getString("phoneNumber")
        myRef = FirebaseDatabase.getInstance().reference
        myRef!!.child("Users").child(phoneNumber).child("location")
                .addValueEventListener(object: ValueEventListener{
                    override fun onCancelled(p0: DatabaseError?) {

                    }

                    override fun onDataChange(dataSnapShot: DataSnapshot?) {
                        try {
                            val tableData = dataSnapShot!!.value as HashMap<String, Any>
                            val latitude = tableData["latitude"].toString()
                            val longitude = tableData["longitude"].toString()
                            MapsActivity.sydney = LatLng(latitude.toDouble(),longitude.toDouble())
                            MapsActivity.lastSeen = tableData["last seen"].toString()

                            loadMap()
                        }catch (e:Exception){
                            Toast.makeText(applicationContext,"Error: "+e.message,Toast.LENGTH_LONG).show()
                            return
                        }
                    }

                }
                )
    }

    fun loadMap(){

        // Obtain the SupportMapFragment and get notified when the map is ready to be used.


        val mapFragment = supportFragmentManager
                .findFragmentById(R.id.map) as SupportMapFragment
        mapFragment.getMapAsync(this)

    }

    /**
     * Manipulates the map once available.
     * This callback is triggered when the map is ready to be used.
     * This is where we can add markers or lines, add listeners or move the camera. In this case,
     * we just add a marker near Sydney, Australia.
     * If Google Play services is not installed on the device, the user will be prompted to install
     * it inside the SupportMapFragment. This method will only be triggered once the user has
     * installed Google Play services and returned to the app.
     */
    companion object {
        var sydney = LatLng(-34.0, 151.0)
        var lastSeen = "not defined"
    }
    override fun onMapReady(googleMap: GoogleMap) {
        mMap = googleMap

        // Add a marker in Sydney and move the camera

        mMap.addMarker(MarkerOptions().position(sydney).title(lastSeen))
        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(sydney,15f))
    }
}

我已经尝试了我所知道的所有内容，并且我已经编写了与教师相同的代码但是我的工作没有用，它给了我错误：null无法转换为非null类型的com.google.android.gms。此行的maps.supportmapfragment
val mapFragment = supportFragmentManager .findFragmentById(R.id.map) as SupportMapFragment
所以调试后这行返回null，我不知道为什么 - 它是内置的不是我的 - 我甚至试图删除我对该文件的所有调整但是地图没有显示这是教官代码：
`

class MapsActivity : AppCompatActivity(), OnMapReadyCallback {

    private lateinit var mMap: GoogleMap

    var dDatabaseRef:DatabaseReference?=null
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_maps)

        val bundle:Bundle=intent.extras
        val phoneNumber =bundle.getString("phoneNumber")
        dDatabaseRef=FirebaseDatabase.getInstance().reference

        dDatabaseRef!!.child("Users").child(phoneNumber)
                .child("location").addValueEventListener(object:ValueEventListener{

            override fun onDataChange(dataSnapshot: DataSnapshot?) {

                try{
                    val td= dataSnapshot!!.value as HashMap<String,Any>
                    val lat =td["lat"].toString()
                    val log =td["log"].toString()
                    MapsActivity.sydney= LatLng(lat.toDouble(),log.toDouble())
                    MapsActivity.lastOnline= td["lastOnline"].toString()
                    loadMap()
                }catch (ex:Exception){}
            }
            override fun onCancelled(p0: DatabaseError?) {

            }
        })
    }


    fun loadMap(){
        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        val mapFragment = supportFragmentManager
                .findFragmentById(R.id.map) as SupportMapFragment
        mapFragment.getMapAsync(this)
    }
    /**
     * Manipulates the map once available.
     * This callback is triggered when the map is ready to be used.
     * This is where we can add markers or lines, add listeners or move the camera. In this case,
     * we just add a marker near Sydney, Australia.
     * If Google Play services is not installed on the device, the user will be prompted to install
     * it inside the SupportMapFragment. This method will only be triggered once the user has
     * installed Google Play services and returned to the app.
     */
    companion object{
        var sydney = LatLng(-34.0, 151.0)
        var lastOnline="not defined"
    }
    override fun onMapReady(googleMap: GoogleMap) {
        mMap = googleMap

        // Add a marker in Sydney and move the camera

        mMap.addMarker(MarkerOptions().position(sydney).title(lastOnline))
        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(sydney,15f))
    }
}

`
正如你所看到的，两个代码之间没有任何差别

所以，如果有人可以提供帮助我将会非常充实

Kotlin与Android中的地图 - 地图不显示

0 个答案: