地点返回NULL [英] Location returns NULL

问题描述

我写一个Android应用程序，返回经度和纬度，但位置持有空值。

请看看你是否可以明白为什么，它整天缠着我。低于code：

 公共类例子扩展活动{

    公共静态双重纬度;
    公共静态双经度;
    LocationManager流明;
    LocationListener的LL;
    地点位置;


  / **第一次创建活动时调用。 * /
  @覆盖
  公共无效的onCreate（包savedInstanceState）{
      super.onCreate（savedInstanceState）;
      的setContentView（R.layout.questions）;


      LM =（LocationManager）getSystemService（Context.LOCATION_SERVICE）;

      LL =新MyLocationListener（）;

      lm.requestLocationUpdates（LocationManager.GPS_PROVIDER，0，0，LL）;
      //位置= lm.getLastKnownLocation（lm.getBestProvider（标准，真））;

      按钮B =（按钮）findViewById（R.id.button2）;
      b.setOnClickListener（新View.OnClickListener（）{

        @覆盖
        公共无效的onClick（查看为arg0）{
            字符串商= Settings.Secure.getString（getContentResolver（），Settings.Secure.LOCATION_PROVIDERS_ALLOWED）;
             INT索引1 = provider.indexOf（GPS）;
             如果（索引1℃，）
                 // GPS未启用，通话MSGBOX
                 showMsgBox（全球定位系统处于关闭状态，GPS是关闭打开它？，打开）;
             其他
            我们到了吗（）; }}）;
}

  私人无效areWeThereYet（）
  {
      如果（weAreThere（））
      {
          toastMsg（在正确的地方）;
      }
      否则，如果（位置！= NULL）
          toastMsg（现在还没有）;
  }

私人布尔weAreThere（）{

     位置= lm.getLastKnownLocation（LocationManager.GPS_PROVIDER）;

    如果（位置！= NULL）
    {
        经度= location.getLongitude（）;
        纬度= location.getLatitude（）;
        toastMsg（北纬++经度）;
        返回inCorrectPlace（问题）;
    }
    其他
    {
        toastMsg（位置还没有准备好）;
        返回false;
    }
}

私人无效toastMsg（弦乐味精）{
        吐司面包= Toast.makeText（这一点，味精，2000年）;
        toast.setGravity（Gravity.BOTTOM，0，0）;
            toast.show（）;
}
}
 

解决方案

如果该GPS还没有得到过由于设备被引导的位置，该位置的对象将是无效的。有一件事你可以做的是试图得到一个GPS定位和网络位置，并检查二，看其中任何一项都不错（或哪一个更好），并使用该位置。

I am writing an Android app that returns longitude and latitude, however location holds a Null value.

Please see if you can see why, Its been bugging me all day. Code below:

public class example extends Activity {

    public static double latitude;
    public static double longitude;
    LocationManager lm;
    LocationListener ll;
    Location location;


  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.questions);


      lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);

      ll = new MyLocationListener();

      lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, ll);
      //location = lm.getLastKnownLocation(lm.getBestProvider(criteria, true)); 

      Button b = (Button) findViewById(R.id.button2);
      b.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
            String provider = Settings.Secure.getString(getContentResolver(), Settings.Secure.LOCATION_PROVIDERS_ALLOWED);
             int index1 = provider.indexOf("gps");
             if(index1 < 0)
                 // gps not enabled, call msgbox    
                 showMsgBox("GPS is off", "GPS is off. Turn it on?", "Turn on");
             else
            areWeThereYet(); }});
}

  private void areWeThereYet()
  {
      if(weAreThere())
      {
          toastMsg("in correct place");     
      }
      else if(location!=null)
          toastMsg("not there yet");
  }

private boolean weAreThere() {

     location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);

    if (location!=null)
    {
        longitude = location.getLongitude();
        latitude = location.getLatitude();
        toastMsg(latitude + " " + longitude);
        return inCorrectPlace(question);
    }
    else
    {
        toastMsg("Location not ready yet");
        return false;
    }
}

private void toastMsg(String msg) {
        Toast toast = Toast.makeText(this, msg, 2000);
        toast.setGravity(Gravity.BOTTOM, 0, 0);
            toast.show();
}
}

解决方案

If the GPS has not ever gotten a location since the device was booted, the location object will be null. One thing you can do is attempt to get a GPS location and a network location, and check to two to see if either of them are good (or which one is better) and use that location.

这篇关于地点返回NULL的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！