1. String-related classes (string, StringBuffer)---string------The Java.lang.String class represents an immutable sequence of characters------"XXXXX" is an object of the class------common construction method of the String class: (see API document)--------string ( String original)-----------Create a copy of the string object original--------string (char[] value)----------- Creates a string object with a character number--------string (char[] value, int offset, int count)----------- Creates a string object from the count character sequence starting with the offset entry with a single character array
2. StringBuffer class---java.lang.Stringbuffer represents a variable sequence of characters---StringBuffer andstring is similar, butStringBuffer can make changes to its string. ---common construction methods for the StringBuffer class:------StringBuffer (): Creates a "null" that does not contain a sequence of charactersStringBuffer Object------StringBuffer (String str): Create aThe StringBuffer object that contains the same sequence of characters as the String Object str.3. Basic data type packing class---Wrapper classes (such as Integer, double, etc.) these classes encapsulate a corresponding base data type value and provide it with a series of manipulations. ---Take the Java.lang.Integer class as an example: Construction method:------Integer (int value)------Integer (String s)4. File Class---java.io.File class represents the System file name (path and file name)5, Java.lang.Enum Enumeration type:---enum type:------can only take one of the specific values------use the ENUM keyword------is the Java.lang.Enum type---Example:------testenum.java6, Summarizes---string-related------regular Expressions---The underlying type wrapper class---Math---File-----Recursive---Enumeration
1. String-related classes (string, StringBuffer)---string------The Java.lang.String class represents an immutable sequence of characters------"XXXXX" is an object of the class------common construction method of the String class: (see API document)--------string ( String original)-----------Create a copy of the string object original--------string (char[] value)----------- Creates a string object with a character number--------string (char[] value, int offset, int count)----------- Creates a string object from the count character sequence starting with the offset entry with a single character array
2. StringBuffer class---java.lang.Stringbuffer represents a variable sequence of characters---StringBuffer andstring is similar, butStringBuffer can make changes to its string. ---common construction methods for the StringBuffer class:------StringBuffer (): Creates a "null" that does not contain a sequence of charactersStringBuffer Object------StringBuffer (String str): Create aThe StringBuffer object that contains the same sequence of characters as the String Object str.3. Basic data type packing class---Wrapper classes (such as Integer, double, etc.) these classes encapsulate a corresponding base data type value and provide it with a series of manipulations. ---Take the Java.lang.Integer class as an example: Construction method:------Integer (int value)------Integer (String s)4. File Class---java.io.File class represents the System file name (path and file name)5, Java.lang.Enum Enumeration type:---enum type:------can only take one of the specific values------use the ENUM keyword------is the Java.lang.Enum type---Example:------testenum.java6, Summarizes---string-related------regular Expressions---The underlying type wrapper class---Math---File-----Recursive---Enumeration
Vi. Common Java Classes
