Error: link of class 'lcom /... /Persistentconnectionlistener; 'failed... Vfy: unable

When XMPP push is used, the following error is reported:

06-05 14:12:10. 710: W/dalvikvm (8735): link of class 'lcom/.../persistentconnectionlistener; 'failed'

14:12:10-05. 710: E/dalvikvm (8735): cocould not find class 'com ..... persistentconnectionlistener ', referenced from method com ..... xmppmanager. <init>
14:12:10-05. 710: W/dalvikvm (8735): vfy: unable to resolve new-instance 280 (lcom /... /persistentconnectionlistener;) in lcom /... /xmppmanager;
06-05 14:12:10. 710: W/dalvikvm (8735): vfy: unable to find class referenced in signature (lorg/jivesoftware/smack/xmppconnection ;)
06-05 14:12:10. 710: W/dalvikvm (8735): vfy: unable to resolve virtual method 1600: lorg/jivesoftware/smack/xmppconnection;. isconnected () Z
06-05 14:12:10. 710: W/dalvikvm (8735): vfy: unable to resolve virtual method 1600: lorg/jivesoftware/smack/xmppconnection;. isconnected () Z
06-05 14:12:10. 720: W/dalvikvm (8735): vfy: unable to find class referenced in signature (lorg/jivesoftware/smack/xmppconnection ;)
06-05 14:12:10. 720: W/dalvikvm (8735): vfy: unable to find class referenced in signature (lorg/jivesoftware/smack/connectionlistener ;)
06-05 14:12:10. 720: W/dalvikvm (8735): vfy: unable to find class referenced in signature (lorg/jivesoftware/smack/packetlistener ;)
06-05 14:12:10. 720: W/dalvikvm (8735): vfy: unable to find class referenced in signature (lorg/jivesoftware/smack/xmppconnection ;)
06-05 14:12:10. 720: W/dalvikvm (8735): link of class 'lcom/.../persistentconnectionlistener; 'failed'
06-05 14:12:10. 720: W/dalvikvm (8735): link of class 'lcom/.../notificationpacketlistener; 'failed'
06-05 14:12:10. 720: W/dalvikvm (8735): threadid = 1: thread exiting with uncaught exception (group = 0x0000bb9d8)
06-05 14:12:10. 730: E/androidruntime (8735): Fatal exception: Main
06-05 14:12:10. 730: E/androidruntime (8735): Java. Lang. noclassdeffounderror: com... persistentconnectionlistener
06-05 14:12:10. 730: E/androidruntime (8735): At com... xmppmanager. <init> (xmppmanager. Java: 105)
06-05 14:12:10. 730: E/androidruntime (8735): At com... notificationservice. oncreate (icationicationservice. Java: 122)
06-05 14:12:10. 730: E/androidruntime (8735): at Android. App. activitythread. handlecreateservice (activitythread. Java: 2266)
06-05 14:12:10. 730: E/androidruntime (8735): at Android. App. activitythread. Access $1600 (activitythread. Java: 126)
06-05 14:12:10. 730: E/androidruntime (8735): at Android. App. activitythread $ H. handlemessage (activitythread. Java: 1204)
06-05 14:12:10. 730: E/androidruntime (8735): at Android. OS. handler. dispatchmessage (handler. Java: 99)
06-05 14:12:10. 730: E/androidruntime (8735): at Android. OS. Looper. Loop (Looper. Java: 137)
06-05 14:12:10. 730: E/androidruntime (8735): at Android. App. activitythread. Main (activitythread. Java: 4439)
06-05 14:12:10. 730: E/androidruntime (8735): At java. Lang. Reflect. method. invokenative (native method)
06-05 14:12:10. 730: E/androidruntime (8735): At java. Lang. Reflect. method. Invoke (method. Java: 511)
06-05 14:12:10. 730: E/androidruntime (8735): At com. Android. Internal. OS. zygoteinit $ methodandargscaller. Run (zygoteinit. Java: 787)
06-05 14:12:10. 730: E/androidruntime (8735): At com. Android. Internal. OS. zygoteinit. Main (zygoteinit. Java: 554)

06-05 14:12:10. 730: E/androidruntime (8735 ):
At Dalvik. system. nativestart. Main (native method)

Solution:

Check whether the required package has been imported,

If all the packages have been imported, right-click the libs folder of the project, that is, right-click the folder of the jar package to be imported, and choose build path> use as source folder.

This should solve the problem. Run it again ~