How to check wether the activity i am starting is the activity which is running?

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http://stackoverflow.com – I have 6 Buttons, for 1st 3 Buttons i want to start same activity and for other 3 Buttons separate new activities. So problem arises when i click on 1st button and then the second Button which starts same activity because we can not start same activity from same activity. So I just need to know weather the activity which i am going to start is the same activity which is running, based on that if same activity then i'll just update some UI contents else start new activity. So anyone cam help me to know this ? (HowTos)