Android error Dx trouble writing output:already prepared

Question

I am building an app using Smack . After running app in Eclipse emulator the apk gets installed successfully but it seems not responding. after clicking on it I am getting the alert "unfortunately the app stopped working ". Please help me to solve the same . Logcat :

01-13 05:55:17.117: E/AndroidRuntime(1067): FATAL EXCEPTION: main
01-13 05:55:17.117: E/AndroidRuntime(1067): Process: com.demo.xmppchat, PID: 1067
01-13 05:55:17.117: E/AndroidRuntime(1067): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.demo.xmppchat/com.demo.xmppchat.CustomizedListView}: java.lang.NullPointerException
01-13 05:55:17.117: E/AndroidRuntime(1067):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2176)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at android.app.ActivityThread.access$700(ActivityThread.java:135)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at android.os.Handler.dispatchMessage(Handler.java:102)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at android.os.Looper.loop(Looper.java:137)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at android.app.ActivityThread.main(ActivityThread.java:4998)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at java.lang.reflect.Method.invokeNative(Native Method)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at java.lang.reflect.Method.invoke(Method.java:515)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at dalvik.system.NativeStart.main(Native Method)
01-13 05:55:17.117: E/AndroidRuntime(1067): Caused by: java.lang.NullPointerException
01-13 05:55:17.117: E/AndroidRuntime(1067):     at com.demo.xmppchat.CustomizedListView.onCreate(CustomizedListView.java:80)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at android.app.Activity.performCreate(Activity.java:5243)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
01-13 05:55:17.117: E/AndroidRuntime(1067):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2140)
01-13 05:55:17.117: E/AndroidRuntime(1067):     ... 11 more

Answer 1

Open properties of your project -> Java build path -> uncheck "Android Private Libraries" and "Android Dependencies".