## Quantifiers in JavaIn Java, regular expressions are frequently employed to define search patterns using sequences of characters. Quantifiers, which determine the number of occurrences of a character or group of characters, are integral to specifying the extent of the search. These expressions help define the rules for pattern matching within the given text or data. **X* (Zero or More Occurrences):**- The quantifier specifies that the element
**X**may appear zero or more times in the given string. - Example: If
**X**is the character 'a', the pattern "a*" would match an empty string, "a", "aa", "aaa", and so forth.
- The quantifier specifies that the element
**X? (Zero or One Occurrence):**- The quantifier indicates that the element
**X**may appear zero or one time in the given string. - Example: If
**X**is the character 'b', the pattern "b?" would match an empty string or "b".
- The quantifier indicates that the element
**X+ (One or More Occurrences):**- The quantifier specifies that the element
**X**must appear at least once in the given string, but it can also appear more times. - Example: If
**X**is the character 'c', the pattern "c+" would match "c", "cc", "ccc", and so on.
- The quantifier specifies that the element
**X{n} (Exactly n Occurrences):**- The quantifier mandates that the element
**X**appear exactly**n**times in the given string. - Example: If
**X**is the character 'd', the pattern "d{3}" would match "ddd".
- The quantifier mandates that the element
**X{n,} (At Least n Occurrences):**- The quantifier specifies that the element
**X**must appear at least**n**times in the given string, but it can also appear more times. - Example: If
**X**is the character 'e', the pattern "e{2,}" would match "ee", "eee", and so forth.
- The quantifier specifies that the element
**X{n, m} (Occurrences Between n and m):**- The quantifier defines a range, stating that the element
**X**must appear between**n**and**m**times in the given string. - Example: If
**X**is the character 'f', the pattern "f{2,4}" would match "ff", "fff", or "ffff", but not "f" or "fffff".
- The quantifier defines a range, stating that the element
## Greedy Quantifier (Default)A greedy quantifier is the default behaviour in regular expressions, and it matches as much of the input as possible while still allowing the overall pattern to match. In other words, it tries to consume as many characters as possible and satisfy the entire regular expression. ## Algorithm:
- Find the longest sequence of digits in the input string for each iteration.
## Implementation:
Match: 123 Match: 456 ## Reluctant Quantifier (Appending a ? after quantifier)Reluctant quantifiers in Java regular expressions, also known as non-greedy or lazy quantifiers, match as little as possible, contrasting with greedy quantifiers. They match the first character initially and add more from the input string if needed. Appending a "?" to a greedy quantifier turns it into a reluctant quantifier. It is useful for extracting the shortest possible matching sequence in text processing tasks. ## Algorithm:
- On each iteration, find the next Match in the input string.
## Implementation:
Match: 1 Match: 2 Match: 3 Match: 4 Match: 5 Match: 6 ## Possessive Quantifier (Appending a + after quantifier)A possessive quantifier in Java regular expressions is denoted by appending a plus sign + after a regular quantifier. The quantifier is similar to a greedy quantifier but with distinct behaviour. A possessive quantifier matches as much as possible and does not backtrack, even if doing so would allow the overall pattern to match. ## Algorithm:
- On each iteration, find the next Match in the input string.
## Implementation:
Match: cccc |

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