Ecplise debugging java. lang. NoClassDefFoundError exception Solution

The external android project is imported to ecplise. The compilation is normal and an error is returned. The logcat is as follows: 12-19 10:55:25. 915: E/AndroidRuntime (2929): fatal exception: main12-19 10:55:25. 915: E/AndroidRuntime (2929): java. lang. noClassDefFoundError: com. guet. siriCN. mainActivity $1 www.2cto. com12-19 10:55:25. 915: E/AndroidRuntime (2929): at com. XXX. mainActivity. <init> (MainActivity. java: 189) 12-19 10:55:25. 915: E/AndroidRuntime (2929): at java. lang. class. newInstanceImpl (Native Method) 12-19 10:55:25. 915: E/AndroidRuntime (2929): at java. lang. class. newInstance (Class. java: 1429) 12-19 10:55:25. 915: E/AndroidRuntime (2929): at android. app. instrumentation. newActivity (Instrumentation. java: 1021) 12-19 10:55:25. 915: E/AndroidRuntime (2929): at android. app. activityThread. extends mlaunchactivity (ActivityThread. java: 2577) 12-19 10:55:25. 915: E/AndroidRuntime (2929): at android. app. activityThread. handleLaunchActivity (ActivityThread. java: 2679) 12-19 10:55:25. 915: E/AndroidRuntime (2929): at android. app. activityThread. access $2300 (ActivityThread. java: 125) 12-19 10:55:25. 915: E/AndroidRuntime (2929): at android. app. activityThread $ H. handleMessage (ActivityThread. java: 2033) 12-19 10:55:25. 915: E/AndroidRuntime (2929): at android. OS. handler. dispatchMessage (Handler. java: 99) 12-19 10:55:25. 915: E/AndroidRuntime (2929): at android. OS. logoff. loop (logoff. java: 123) 12-19 10:55:25. 915: E/AndroidRuntime (2929): at android. app. activityThread. main (ActivityThread. java: 4627) 12-19 10:55:25. 915: E/AndroidRuntime (2929): at java. lang. reflect. method. invokeNative (Native Method) 12-19 10:55:25. 915: E/AndroidRuntime (2929): at java. lang. reflect. method. invoke (Method. java: 521) 12-19 10:55:25. 915: E/AndroidRuntime (2929): at com. android. internal. OS. zygoteInit $ MethodAndArgsCaller. run finds many reasons. When an external jar package is introduced, if the jar package is not in the lib directory, it needs to be referenced separately. The solution is as follows: properties-java build path-order and export page