E/AndroidRuntime: FATAL EXCEPTION: main
Process: paho.mqtt.java.example, PID: 30824
java.lang.RuntimeException: Error receiving broadcast Intent { act=android.net.conn.CONNECTIVITY_CHANGE flg=0x4000010 (has extras) } in org.eclipse.paho.android.service.MqttService$NetworkConnectionIntentReceiver@4228fd88
at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:808)
at android.os.Handler.handleCallback(Handler.java:808)
at android.os.Handler.dispatchMessage(Handler.java:103)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5368)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:828)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:644)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at org.eclipse.paho.client.mqttv3.MqttAsyncClient.stopReconnectCycle(MqttAsyncClient.java:1120)
at org.eclipse.paho.client.mqttv3.MqttAsyncClient.reconnect(MqttAsyncClient.java:1057)
at org.eclipse.paho.android.service.MqttConnection.reconnect(MqttConnection.java:1049)
at org.eclipse.paho.android.service.MqttService.reconnect(MqttService.java:342)
at org.eclipse.paho.android.service.MqttService$NetworkConnectionIntentReceiver.onReceive(MqttService.java:827)
at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:798)
at android.os.Handler.handleCallback(Handler.java:808)
at android.os.Handler.dispatchMessage(Handler.java:103)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5368)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:828)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:644)
at dalvik.system.NativeStart.main(Native Method)
解决办法：
Am aslo got same error, which version are you using in mqttclient ?
I think you are using this version
compile 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.1.0'
compile 'org.eclipse.paho:org.eclipse.paho.android.service:1.1.1'
Pls update the version
compile 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.2.0'
compile 'org.eclipse.paho:org.eclipse.paho.android.service:1.1.1'
My side its working fine
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原文链接：https://blog.csdn.net/xuwenwen_2013/article/details/79701121