Question

好的，所以我在GPS.class使用这个GPS位置，我一直得到Null Object参考，不知道为什么。这是我的代码：

 boolean permissionGranted = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED;

    if(permissionGranted)
    {
        if (GPS.sharedInstance(AppDashboard.this).canGetLocation() && GPS.sharedInstance(this).isPermissionEnabled()) {
            double lat = GPS.sharedInstance(AppDashboard.this).getLatitude();
            double lon = GPS.sharedInstance(AppDashboard.this).getLongitude();
            Log.e(TAG, "Location: " + lat + "/"+ lon);
        }
        else
        {
            Log.e(TAG, "Can't get GPS locations");
        }
    } else {
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 200);
    }

我的宣言：

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-feature android:name="android.hardware.location.gps" />

我的Logcat：

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'double android.location.Location.getLatitude()' on a null object reference
at com.gpsApp.utility.GPS.getLatitude(GPS.java:113)

GPS Class 113

public double getLatitude() {
    if (_locationManager != null) {
        _latitude = _location.getLatitude();
    }

    return _latitude;
}

Answer 1

使用此行

{{ item.form_date|timesince:item.to_date }}

而不是

boolean permissionGranted = ActivityCompat.checkSelfPermission(getApplicationContext, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED;

Answer 2

您正在从public double getLatitude()类调用GPS，但_location变量未初始化，因此您获得NullPointerException。

在调用getLatitude()之前，请尝试从您的public Location getLastKnownLocation()课程中调用GPS。此调用将初始化_location变量。

位置

2 个答案: