diff --git a/src/main/java/com/whdc/mqtt/Sub.java b/src/main/java/com/whdc/mqtt/Sub.java
index 9bca41e..6bc1207 100644
--- a/src/main/java/com/whdc/mqtt/Sub.java
+++ b/src/main/java/com/whdc/mqtt/Sub.java
@@ -41,9 +41,9 @@ public class Sub {
 
             @Override
             public void messageArrived(String topic, MqttMessage mqttMessage) {
-                byte[] payload = mqttMessage.getPayload();
-                String msg = new String(payload);
                 try {
+                    byte[] payload = mqttMessage.getPayload();
+                    String msg = new String(payload);
                     Sub.this.onMessageListener.onMessage(msg);
                 } catch (Throwable e) {
                     e.printStackTrace();