【The Java™ Tutorials】【Regular Expressions】6. Quantifiers
Quantifiersallowyoutospecifythenumberofoccurrencestomatchagainst.GreedyReluctantPossessiveMeaningX?X??X?+X,onceornotatallX*X*?X*+X,zeroormoretimesX+X+?X++X,oneormoretimesX{n}X{n}?X{n}+X,exactlyntimesX