Question

我是Android的新手，我正在创建一个应用程序，用于计算从开始纬度和经度到当前纬度和经度的距离。下面是关于获取纬度和经度距离的代码，其中开始意味着开始，而curr意味着当前。（我刚刚复制了关于如何在互联网上获得两个纬度和经度距离的公式）

public Double getDistance(Double startLat, Double startLong, Double currLat, Double currLong) {

    int radius = 6371; //This is the radius of the earth
    Double distanceLatitude = degreeToRadius(currLat-startLat);
    Double distanceLongitude = degreeToRadius(currLong-startLong);
    Double area =
            Math.sin(distanceLatitude/2) * Math.sin(distanceLatitude/2) +
                    Math.cos(degreeToRadius(startLat)) * Math.cos(degreeToRadius(currLat)) *
                            Math.sin(distanceLongitude/2) * Math.sin(distanceLongitude/2)
            ;
    Double circumference = 2 * Math.atan2(Math.sqrt(area), Math.sqrt(1-area));
    Double totalDistance = radius * circumference;
    return totalDistance;

}

public Double degreeToRadius(Double degreeToRadius) {
    return degreeToRadius * (Math.PI/180);
}

这是我的onLocationChanged函数，它在设备移动时更新纬度和经度，我也在这里设置距离。

@Override
public void onLocationChanged(Location location) {

    String locationMessage = "Latitude: " + location.getLatitude()
            + "Longitude: " + location.getLongitude();

    Double locationLatitude = location.getLatitude();
    Double locationLongitude = location.getLongitude();

    Toast.makeText(getBaseContext(), locationMessage, Toast.LENGTH_LONG).show();
    currentLatitude.setText(locationLatitude.toString());
    currentLongitude.setText(locationLongitude.toString());

    Double startLat = Double.parseDouble(startingLatitude.getText().toString());
    Double startLong = Double.parseDouble(startingLongitude.getText().toString());
    Double currLat = Double.parseDouble(currentLatitude.getText().toString());
    Double currLong = Double.parseDouble(currentLongitude.getText().toString());

    distance.setText(getDistance(startLat, startLong, currLat, currLong).toString() + "KM");

}

每当我启动应用程序时，它都能正常运行，但是当它开始获取位置时，它总是会崩溃。任何的想法？请帮忙。感谢

这是日志

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: com.example.webglider.fitnessapp, PID: 7600
              java.lang.NumberFormatException: Invalid double: ""
                  at java.lang.StringToReal.invalidReal(StringToReal.java:63)
                  at java.lang.StringToReal.parseDouble(StringToReal.java:267)
                  at java.lang.Double.parseDouble(Double.java:301)
                  at com.example.webglider.fitnessapp.MainActivity.onLocationChanged(MainActivity.java:196)
                  at android.location.LocationManager$ListenerTransport._handleMessage(LocationManager.java:290)
                  at android.location.LocationManager$ListenerTransport.access$000(LocationManager.java:219)
                  at android.location.LocationManager$ListenerTransport$1.handleMessage(LocationManager.java:235)
                  at android.os.Handler.dispatchMessage(Handler.java:102)
                  at android.os.Looper.loop(Looper.java:148)
                  at android.app.ActivityThread.main(ActivityThread.java:7325)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)

这是我的MainActivity.java上的第196行

Double startLat = Double.parseDouble(startingLatitude.getText().toString());

Answer 1

尝试以下代码。 android中的位置类具有内置方法以获取两个位置之间的距离。这将为您提供以米为单位的距离。

Location oldLocation = new Location("oldLocation");     
oldLocation.setLatitude(oldLat); 
oldLocation.setLongitude(oldLng);
Location newLocation = new Location("newLocation");
newLocation.setLatitude(newLat); 
newLocation.setLongitude(newLng);
float distance = oldLocation.distanceTo(newLocation) ;

有关参考，请查看官方文档。https://developer.android.com/reference/android/location/Location.html#distanceTo(android.location.Location)

当从两个纬度和经度获得距离时，应用程序崩溃

1 个答案: