Operations on String that are null safe.
IsEmpty/IsBlank - checks if a String is empty (判断字符串是否为空)
Trim/Strip - removes leading and trailing whitespace (删除前后的控制字符、空白字符)
Equals - compares two strings null-safe (判断字符串是否相等)
startsWith - check if a String starts with a prefix null-safe
endsWith - check if a String ends with a suffix null-safe
IndexOf/LastIndexOf/Contains - null-safe index-of checks
IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut - index-of any of a set of Strings
ContainsOnly/ContainsNone/ContainsAny - does String contains only/none/any of these characters
Substring/Left/Right/Mid - null-safe substring extractions
SubstringBefore/SubstringAfter/SubstringBetween - substring extraction relative to other strings (获得相对于分隔符位置的子串)
Split/Join - splits a String into an array of substrings and vice versa (拆分、拼接字符串)
Remove/Delete - removes part of a String
Replace/Overlay - Searches a String and replaces one String with another
Chomp/Chop - removes the last part of a String
AppendIfMissing - appends a suffix to the end of the String if not present (如果字符不以指定的后缀结尾，则在字符串后补充该后缀返回)
PrependIfMissing - prepends a prefix to the start of the String if not present (如果字符不以指定的前缀开头，则在字符串前补充该前缀返回)
LeftPad/RightPad/Center/Repeat - pads a String
UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize - changes the case of a String (改变字符的大小写)
CountMatches - counts the number of occurrences of one String in another
IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable - checks the characters in a String
DefaultString - protects against a null input String (预防 null)
Reverse/ReverseDelimited - reverses a String (反转字符串)
Abbreviate - abbreviates a string using ellipsis
Difference - compares Strings and reports on their differences
LevenshteinDistance - the number of changes needed to change one String into another
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