Sweden held a national preselction named Melodifestivalen 1984 to choose the entry for the Eurovision Song Contest the same year. The winner was the three brothers Herrey, consisting of Richard, Louis and Per. Their song was called "Diggi-loo diggi-ley", and was written by Britt Lindeborg and Torgny Söderberg.

Sweden was the first country to perform at ESC that year. In the voting, they received not less than 5 "douze points" from the other 18 countries. Finally the brothers were victorious, with a total of 145 points - 8 points ahead of Ireland. Sweden had won exactly 10 years earlier, then represented by ABBA.

...
Wikipedia