尝试从Flatter中的注册表获取上下文时出现Kotlin null指针异常
我正在尝试创建一个使用原生Android sdk的颤振插件 我能够编译sdk的.aar库并在项目中使用它们,但sdk要求我获取主要活动的上下文 这是我得到的错误尝试从Flatter中的注册表获取上下文时出现Kotlin null指针异常,kotlin,plugins,flutter,flutter-dependencies,Kotlin,Plugins,Flutter,Flutter Dependencies,我正在尝试创建一个使用原生Android sdk的颤振插件 我能够编译sdk的.aar库并在项目中使用它们,但sdk要求我获取主要活动的上下文 这是我得到的错误 E/MethodChannel#mychart_plugin(16277): Failed to handle method call E/MethodChannel#mychart_plugin(16277): kotlin.KotlinNullPointerException E/MethodChannel#mychart_plug
E/MethodChannel#mychart_plugin(16277): Failed to handle method call
E/MethodChannel#mychart_plugin(16277): kotlin.KotlinNullPointerException
E/MethodChannel#mychart_plugin(16277): at org.ccf.flutter.plugin.mychart_plugin.MychartPlugin.getContext(MychartPlugin.kt:79)
E/MethodChannel#mychart_plugin(16277): at epic.mychart.android.library.api.authentication.WPAPIAuthentication$1.getContext(WPAPIAuthentication.java:564)
E/MethodChannel#mychart_plugin(16277): at epic.mychart.android.library.prelogin.AuthenticationService.libraryLogin(AuthenticationService.java:461)
E/MethodChannel#mychart_plugin(16277): at epic.mychart.android.library.api.authentication.WPAPIAuthentication.login(WPAPIAuthentication.java:411)
E/MethodChannel#mychart_plugin(16277): at org.ccf.flutter.plugin.mychart_plugin.MychartPlugin.onMethodCall(MychartPlugin.kt:42)
E/MethodChannel#mychart_plugin(16277): at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage(MethodChannel.java:201)
E/MethodChannel#mychart_plugin(16277): at io.flutter.embedding.engine.dart.DartMessenger.handleMessageFromDart(DartMessenger.java:88)
E/MethodChannel#mychart_plugin(16277): at io.flutter.embedding.engine.FlutterJNI.handlePlatformMessage(FlutterJNI.java:219)
E/MethodChannel#mychart_plugin(16277): at android.os.MessageQueue.nativePollOnce(Native Method)
E/MethodChannel#mychart_plugin(16277): at android.os.MessageQueue.next(MessageQueue.java:325)
E/MethodChannel#mychart_plugin(16277): at android.os.Looper.loop(Looper.java:142)
E/MethodChannel#mychart_plugin(16277): at android.app.ActivityThread.main(ActivityThread.java:6541)
E/MethodChannel#mychart_plugin(16277): at java.lang.reflect.Method.invoke(Native Method)
E/MethodChannel#mychart_plugin(16277): at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
E/MethodChannel#mychart_plugin(16277): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
下面是我获取上下文的代码
class MychartPlugin: MethodCallHandler, WPAPIAuthentication.IWPOnLoginListener {
private var registrar: PluginRegistry.Registrar? = null
private val LOGIN_REQUEST_CODE = 9876
fun MychartPlugin(registrar: PluginRegistry.Registrar) {
this.registrar = registrar
}
companion object {
@JvmStatic
fun registerWith(registrar: Registrar) {
val channel = MethodChannel(registrar.messenger(), "mychart_plugin")
channel.setMethodCallHandler(MychartPlugin())
}
}
override fun onMethodCall(call: MethodCall, result: Result) {
if (call.method == "getPlatformVersion") {
result.success("Android ${android.os.Build.VERSION.RELEASE}")
} else if (call.method == "MyChartSdkLogin") {
WPAPIAuthentication.login(this, "TURKJ123", "TurkJ123", LOGIN_REQUEST_CODE)
result.success("called MyChartSdkLogin")
} else {
result.notImplemented()
}
}
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent) {
// super.onActivityResult(requestCode, resultCode, data)
if (requestCode == LOGIN_REQUEST_CODE) {
if (resultCode == Activity.RESULT_OK) {
// login successful
Log.i("LoginFragment", "OK")
} else {
// login failed
val result = WPAPIAuthentication.getLoginResult(data)
Log.i("LoginFragment", result.toString())
val errorMessage = result.getErrorMessage(getContext())
if (!errorMessage.isEmpty()) {
Toast.makeText(getContext(), errorMessage, Toast.LENGTH_LONG).show()
}
}
}
}
override fun startActivityForResult(p0: Intent, p1: Int) {
// super.startActivityForResult(p0, p1)
}
override fun getSupportFragmentManager(): FragmentManager {
val act = registrar!!.activity() as FragmentActivity
return act.getSupportFragmentManager()
}
override fun getContext(): Context {
val cxt = registrar!!.context()
return cxt
}
}
注意我从sdk重写的override getContext()方法,我认为对注册表的这个上下文调用就是我的KotlinNullPointerException来自
getContext
中的注册器代码>。而register
是一个可为空的字段,您可以将其初始化为null
,并且只能在您从未调用的方法中进行设置。请注意,funMyChartPlugin
不是构造函数,您可以将其称为
val plugin = MychartPlugin()
plugin.MychartPlugin(registrar)
但似乎没有任何理由首先让register
为空或可变。你可以换成
class MychartPlugin(private val registrar: Registrar): ...
及
谢谢,我刚回到科特林,所以我生锈了,哈哈
fun registerWith(registrar: Registrar) {
val channel = MethodChannel(registrar.messenger(), "mychart_plugin")
channel.setMethodCallHandler(MychartPlugin(registrar))
}