Android Kotlin 更新 position

Question

我正在處理我的第一個 Android 項目。 我可以拉出最后一個 GPS 位置，但是當我移動 position 時，它不會更新。 如果我切換到地圖應用程序然后回到我的應用程序，GPS 位置將更新，所以這告訴我我需要以某種方式查詢系統以更新當前位置，但無法弄清楚如何做到這一點。

我錯過了什么？

下面是我目前正在使用的。

class MainActivity : AppCompatActivity() {

    private lateinit var fusedLocationProviderClient: FusedLocationProviderClient
    private lateinit var tvLatitude:TextView
    private lateinit var tvLongitude:TextView

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

        fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this)
        tvLatitude=findViewById(R.id.tvLat)
        tvLongitude=findViewById(R.id.tvLon)


        val cmdUpdateLocation = findViewById<Button>(R.id.cmdUpdateLocation)

        cmdUpdateLocation?.setOnClickListener()
        {
            getCurrentLocation()
        }
        
        getCurrentLocation()
    }

    private fun getCurrentLocation() {
        if(checkPermissions())
        {
            if(isLocationEnabled())
            {
                //FInal lat and lon
                if (ActivityCompat.checkSelfPermission(
                        this,
                        Manifest.permission.ACCESS_FINE_LOCATION
                    ) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(
                        this,
                        Manifest.permission.ACCESS_COARSE_LOCATION
                    ) != PackageManager.PERMISSION_GRANTED
                ) {
                    requestPermission()
                    return
                }
                fusedLocationProviderClient.lastLocation.addOnCompleteListener(this){ task->
                    val location: Location?=task.result
                    if(location==null)
                    {
                        Toast.makeText(applicationContext,"Nul received",Toast.LENGTH_SHORT).show()
                    }
                    else
                    {
                        Toast.makeText(applicationContext,"Get Success",Toast.LENGTH_SHORT).show()
                        tvLatitude.text=""+location.latitude
                        tvLongitude.text=""+location.longitude
                    }
                }
            }
            else
            {
                //Settings Open
                Toast.makeText(applicationContext,"Turn on Location",Toast.LENGTH_SHORT).show()
                val intent=Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS)
                startActivity(intent)

            }
        }
        else
        {
                //Request Permission here
            requestPermission()

        }

    }


    private fun isLocationEnabled():Boolean{
        var locationManager:LocationManager=getSystemService(Context.LOCATION_SERVICE) as LocationManager
        return locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)||locationManager.isProviderEnabled(
            LocationManager.GPS_PROVIDER
        )
    }

    private fun requestPermission() {
        ActivityCompat.requestPermissions(
            this,arrayOf(android.Manifest.permission.ACCESS_COARSE_LOCATION,
            android.Manifest.permission.ACCESS_FINE_LOCATION),
            PERMISSION_REQUEST_ACCESS_LOCATION
        )
    }

    companion object{
            private const val PERMISSION_REQUEST_ACCESS_LOCATION=100
        }

    private fun checkPermissions():Boolean
    {
        if(ActivityCompat.checkSelfPermission(this,
            android.Manifest.permission.ACCESS_COARSE_LOCATION)
            ==PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this,
            Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED)
        {
                return true
        }
            return false
    }

    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<out String>,
        grantResults: IntArray
    ) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)

        if(requestCode== PERMISSION_REQUEST_ACCESS_LOCATION)
        {
            if(grantResults.isNotEmpty() && grantResults[0]==PackageManager.PERMISSION_GRANTED)
            {
                Toast.makeText(applicationContext,"Granted",Toast.LENGTH_SHORT).show()
                getCurrentLocation()
            }
            else
            {
                Toast.makeText(applicationContext,"Denied",Toast.LENGTH_SHORT).show()
            }
        }
    }
}

Answer 1

您需要調用 requestLocationUpdates，而不是 lastLocation。 lastLocation 僅返回最后一個已知位置一次，並且經常返回 null（如果位置未打開）。 它不會打開位置。