Bar bar5M_0 = history.getBar(instrument, Period.FIVE_MINS, OfferSide.BID, 0);
IBar bar5M_20 = history.getBar(instrument, Period.FIVE_MINS, OfferSide.BID, 20);

double[] sma = indicators.ema(instrument, Period.FIVE_MINS, OfferSide.BID, AppliedPrice.CLOSE, periodIndicateur, Filter.NO_FILTER, bar5M_20.getTime(), bar5M_0.getTime());

double valeur1 =0;

if(sma.length > 1) {
valeur1 = Math.abs((sma[10] - sma[20]));
}


But, i have really no idea how to creates indicator with this idea.

indicator : EMA of timeperiod 20

outputs : indicate the difference between 2 value of the array example array[5] - array[0] ...

Thanks for your help