Java Api--character Class

1. Overview of the character class· The Character class wraps the value of a basic type char in an object · In addition, the class provides several methods to determine the categories of characters (lowercase letters, numbers, and so on) and to convert characters from uppercase to lowercase, and vice versa 2. Construction Method

 Public class CharacterDemo01 {    publicstaticvoid  main (string[] args) {           Create object        new Character (' a ');        System.out.println ("ch:" +ch);}    }

3.character class member method public static Boolean isuppercase (char ch): Determines whether the given character is uppercase characters        public static Boolean islowercase (char ch): Determines whether the given character is lowercase characters       public static Boolean isdigit (char ch): Determines whether a given character is a numeric character       public static char touppercase (char ch): Converts the given character to uppercase characters       public static char tolowercase (char ch): Converts the given character to lowercase characters

 Public classCharacterDemo02 { Public Static voidMain (string[] args) {//Public Static Boolean isuppercase (char ch): Determines whether the given character is uppercase charactersSystem.out.println ("isuppercase:" + character.isuppercase (' A '));//isuppercase:trueSystem.out.println ("isuppercase:" + character.isuppercase (' a '));//Isuppercase:falseSystem.out.println ("isuppercase:" + character.isuppercase (' 0 '));//Isuppercase:falseSystem.out.println ("-----------------------------------------"); //Public Static Boolean islowercase (char ch): Determines whether the given character is lowercase charactersSystem.out.println ("islowercase:" + character.islowercase (' A '));//Islowercase:falseSystem.out.println ("islowercase:" + character.islowercase (' a '));//islowercase:trueSystem.out.println ("islowercase:" + character.islowercase (' 0 '));//Islowercase:falseSystem.out.println ("-----------------------------------------"); //Public Static Boolean isdigit (char ch): Determines whether a given character is a numeric characterSystem.out.println ("isdigit:" + character.isdigit (' A '));//Isdigit:falseSystem.out.println ("isdigit:" + character.isdigit (' a '));//Isdigit:falseSystem.out.println ("isdigit:" + character.isdigit (' 0 '));//isdigit:trueSystem.out.println ("-----------------------------------------"); //Public Static char touppercase (char ch): Converts the given character to uppercase charactersSystem.out.println ("toUpperCase:" + character.touppercase (' A '));//touppercase:aSystem.out.println ("toUpperCase:" + character.touppercase (' a '));//touppercase:aSystem.out.println ("-----------------------------------------"); //Public Static char tolowercase (char ch): Converts the given character to lowercase charactersSystem.out.println ("toLowerCase:" + character.tolowercase (' A '));//tolowercase:aSystem.out.println ("toLowerCase:" + character.tolowercase (' a '));//tolowercase:a    }}

4. Exercises: count the number of uppercase characters, lowercase alphabetic characters, and numeric characters in a string. (No other characters are considered)

 Public classCharacterDemo03 { Public Static voidMain (string[] args) {//define three statistical variables.         intBigcount = 0; intSmallcount = 0; intNumbercount = 0; System.out.println ("Please enter a string:"); Scanner SC=NewScanner (system.in); String Line=Sc.nextline (); Char[] ch =Line.tochararray ();  for(inti = 0; i < ch.length; i++){            if(Character.isuppercase (Ch[i])) Bigcount++; Else if(Character.islowercase (Ch[i])) Smallcount++; Else if(Character.isdigit (Ch[i])) Numbercount++; }        //output results can beSYSTEM.OUT.PRINTLN ("Uppercase:" + Bigcount + "X")); System.out.println ("Lowercase letters:" + Smallcount + "X"); System.out.println ("Numeric characters:" + Numbercount + "X"); }}

Output Result:

Please enter a string: Hello 123 ABCAA Capital Letter: 3 Lowercase letters: 7 numeric characters: 3

Java Api--character Class