Android kotlin - 检查 GPS 是否启用时应用停止

Question

这是代码：

        val gps_enabled = locationManager!!.isProviderEnabled(LocationManager.GPS_PROVIDER)

        if(!gps_enabled) {
            Log.d("letsSee", "GPS IS OFF")
        }else{
            Log.d("letsSee", "GPS IS ON")
        }

当我尝试检查 GPS 是打开还是关闭时，应用程序崩溃了。没有检查一切正常，但我仍然需要检查它！有什么想法吗？

09-16 03:59:12.533 32454-32454/com.amoflirt.amoflirt E/dalvikvm: Could not find class 'android.graphics.drawable.RippleDrawable', referenced from method android.support.v7.widget.AppCompatImageHelper.hasOverlappingRendering
09-16 03:59:13.713 32454-32454/com.amoflirt.amoflirt E/AndroidRuntime: FATAL EXCEPTION: main
    kotlin.KotlinNullPointerException
        at com.amoflirt.amoflirt.MainActivity.getLocation(MainActivity.kt:95)
        at com.amoflirt.amoflirt.MainActivity$onCreate.onClick(MainActivity.kt:67)
        at android.view.View.performClick(View.java:4475)
        at android.view.View$PerformClick.run(View.java:18786)
        at android.os.Handler.handleCallback(Handler.java:730)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:176)
        at android.app.ActivityThread.main(ActivityThread.java:5419)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:525)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1046)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:862)
        at dalvik.system.NativeStart.main(Native Method)

Answer 1

确保 locationManager 在您访问它之前已经被定义。

作为旁注，您也许可以使用 Kotlin 的惰性初始化：

val locationManager by lazy { //however you define it normally }

这只会在第一次访问时初始化它，然后在 class.

的生命周期内保留该实例

Android kotlin - 检查 GPS 是否启用时应用停止

Android kotlin - app stopps when check if GPS is enabled

java

gps

android

location

kotlin