How to stop kids from sucking their fingers

My son is 2  1/4  years old.He has the habit of sucking his fingers,while sleeping,gradually he started to keep his hands while watching t.v,while sitting idle and when he got bored.We tried lots of methods but all went in vain.We thought we need to some how stop this habit.Its better to stop before the period when milk teeth falls,because when they suck in that period the tooth will start to grow in the direction where the root was and the roots direction will be changed according the position they suck their fingers and also it can cause some speech problems.We some how finally succeeded in our attempt.Here are the methods we tried.
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Action1:We tried to put gloves in his hand.
Result:He kept the gloves for some time and started to remove it.
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Action 2: We tied a kerchief around his hands
Result:He kept for some time and later he tried to remove the kerchief
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Action 3: We tried to stick adhesive tape around  his finger
Result: He tried to peel it of and during night he voluntarily started asking for the tape,he however removes it after some time.
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Finally we implemented this method,of course  we browsed a lot for it
We started saying "You have become a big boy,big boys wont suck their fingers",we started saying whenever he sucks.gradually in 2-3 days he completely stopped that habit.
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Hurray !!!!!!! we did it !