如何解决使用 BroadcastReceiver 实现 Android 通知操作时出错
我正在尝试使通知中的操作按钮调用一个方法。我阅读并关注了一些文章,但是在我的应用程序中发出通知(应用程序本身编译时没有问题)后,它崩溃并出现以下错误:
D/AndroidRuntime(28351): Shutting down VM
E/AndroidRuntime(28351): FATAL EXCEPTION: main
E/AndroidRuntime(28351): Process: com.example.tasko,PID: 28351
E/AndroidRuntime(28351): java.lang.RuntimeException: Unable to instantiate service com.example.tasko.Stopwatch: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
E/AndroidRuntime(28351): at android.app.ActivityThread.handleCreateService(ActivityThread.java:3940)
E/AndroidRuntime(28351): at android.app.ActivityThread.access$1500(ActivityThread.java:219)
E/AndroidRuntime(28351): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1875)
E/AndroidRuntime(28351): at android.os.Handler.dispatchMessage(Handler.java:107)
E/AndroidRuntime(28351): at android.os.Looper.loop(Looper.java:214)
E/AndroidRuntime(28351): at android.app.ActivityThread.main(ActivityThread.java:7356)
E/AndroidRuntime(28351): at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime(28351): at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
E/AndroidRuntime(28351): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
E/AndroidRuntime(28351): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
E/AndroidRuntime(28351): at android.content.Contextwrapper.getPackageName(Contextwrapper.java:145)
E/AndroidRuntime(28351): at android.content.ComponentName.<init>(ComponentName.java:131)
E/AndroidRuntime(28351): at android.content.Intent.<init>(Intent.java:6510)
E/AndroidRuntime(28351): at com.example.tasko.Stopwatch.<init>(StopwatchService.kt:21)
E/AndroidRuntime(28351): at java.lang.class.newInstance(Native Method)
E/AndroidRuntime(28351): at android.app.AppComponentFactory.instantiateService(AppComponentFactory.java:129)
E/AndroidRuntime(28351): at androidx.core.app.CoreComponentFactory.instantiateService(CoreComponentFactory.java:75)
E/AndroidRuntime(28351): at android.app.ActivityThread.handleCreateService(ActivityThread.java:3935)
E/AndroidRuntime(28351): ... 8 more
这是我的简化代码:
class Stopwatch : Service() {
// error at this line
val intent = Intent(this,ActionReceiver::class.java).apply {
action = "snooze"
}
val pendingIntent: PendingIntent = PendingIntent.getbroadcast(this,snoozeIntent,0)
private fun startForeground() {
...
builder
...
.addAction(R.drawable.ic_round_play_arrow_24,"Play",pendingIntent)
}
}
ActionReceiver.kt:
class ActionReceiver : broadcastReceiver() {
override fun onReceive(context: Context?,intent: Intent?) {
println("Hello!")
}
}
解决方法
问题是我需要在某些方法中初始化我的意图(在我的例子中是 startForeground()
),而不是在类初始化器中,如下所示:
class Stopwatch : Service() {
private fun startForeground() {
...
val intent = Intent(this,ActionReceiver::class.java).apply {
action = "snooze"
}
val pendingIntent: PendingIntent = PendingIntent.getBroadcast(this,snoozeIntent,0)
builder
...
.addAction(R.drawable.ic_round_play_arrow_24,"Play",pendingIntent)
}
}
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