The difference between find, matches, lookingAt matching strings in matcher

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find in matcher,matches, lookingAt match string difference description

Introduction to regular expressions:

Regular expression, also known as regular expression, (Regular Expression, often abbreviated as regex, regexp or RE in code), is a text pattern that includes ordinary characters (for example, letters between a to z) andSpecial characters (called "metacharacters") are a concept in computer science.Regular expressions use a single string to describe and match a series of strings that match a syntactic rule, and are usually used to retrieve and replace text that matches a pattern (rule).
Many programming languages ​​support string manipulation using regular expressions.For example, a powerful regular expression engine is built into Perl.The concept of regular expressions was first popularized by tools in Unix (such as sed and grep), and later widely used in Scala, PHP, C#, Java, C++, Objective-c, Perl, Swift, VBScript, Javascript, Ruby, Python, and more.Regular expressions are usually abbreviated as "regex", with regexp, regex in the singular, and regexps, regexes, and regexen in the plural.

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Introduction to regular expression related methods:
1. The exec() method is a regular expression method used to retrieve the matching of regular expressions in a string.

The function returns an array in which the matching results are stored; if no match is found, the return value is null.

2. The test() method is a regular expression method used to detect whether a string matches a certain pattern,

Returns true if the string contains matching text, false otherwise.

3. The search() method is used to retrieve the specified substring in the string, or to retrieve the substring matching the regular expression, and return the starting position of the substring.

3.1, the search() method uses regular expressions, uses regular expressions to search for strings, and is case-insensitive

3.2. The search() method uses a string, which can be used as a parameter.String arguments are converted to regular expressions

4. The replace() method is used to replace some characters in a string with other characters, or to replace a substring that matches a regular expression.

4.1. The replace() method uses regular expressions, which use regular expressions and are case-insensitive to replace the parameters in the method with the specified content in the string.

4.2. The replace() method uses a string and will receive a string as a parameter.

5. The match() method retrieves a specified value within a string, or finds a match of one or more regular expressions.

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The following describes the difference between find, matches, and lookingAt matching strings in matcher, as follows:

1. Matcher.matches(): Match the entire string, and return true only if the entire string is matched2. Matcher.lookingAt(): start looking from the head of the input, and only return true if the prefix of the string satisfies the pattern3. Matcher.find(): Match the string, the matched string can be in any positionThe difference between the above three: the position of the matched string and whether it is all