Unable to start activity

[Arunachalamkalimuthu]

Fatal Exception: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.rizek.android.users/net.alhazmy13.gota.GotaActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.util.ArrayList.size()' on a null object reference
       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2419)
       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2479)
       at android.app.ActivityThread.-wrap11(ActivityThread.java)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1347)
       at android.os.Handler.dispatchMessage(Handler.java:102)
       at android.os.Looper.loop(Looper.java:148)
       at android.app.ActivityThread.main(ActivityThread.java:5421)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)