Character classes overview and use

Overview:

Character class wraps a value in an object primitive type char addition, the class provides several methods to determine the type of characters (lowercase letters, numbers, etc.), and the characters are converted from upper case to lower case, and vice versa.
 

:( only a constructor)

public Character(char value )

 

package cn.wen_01;

/*
 * 构造方法：
 * 		Character(char value)
 */
public class CharacterDemo {
	public static void main(String[] args) {
		// 创建对象
		// Character ch = new Character((char) 97);
		Character ch = new Character('a');
		System.out.println("ch:" + ch);
	}
}

Character class member method

• static public boolean isUpperCase (char CH): determine whether a given character is uppercase
• static public Boolean isLowerCase (char CH): determining whether the given character lowercase
• public static Boolean isDigit (char CH): determine whether a given character is a numeric character
• static char public toUpperCase (char CH): the given character converted to uppercase
• static char public toLowerCase (char CH): the given character converted to lowercase

package cn.itcast_02;

public class CharacterDemo {
	public static void main(String[] args) {
		// public static boolean isUpperCase(char ch):判断给定的字符是否是大写字符
		System.out.println("isUpperCase:" + Character.isUpperCase('A'));
		System.out.println("isUpperCase:" + Character.isUpperCase('a'));
		System.out.println("isUpperCase:" + Character.isUpperCase('0'));
		System.out.println("-----------------------------------------");
		// public static boolean isLowerCase(char ch):判断给定的字符是否是小写字符
		System.out.println("isLowerCase:" + Character.isLowerCase('A'));
		System.out.println("isLowerCase:" + Character.isLowerCase('a'));
		System.out.println("isLowerCase:" + Character.isLowerCase('0'));
		System.out.println("-----------------------------------------");
		// public static boolean isDigit(char ch):判断给定的字符是否是数字字符
		System.out.println("isDigit:" + Character.isDigit('A'));
		System.out.println("isDigit:" + Character.isDigit('a'));
		System.out.println("isDigit:" + Character.isDigit('0'));
		System.out.println("-----------------------------------------");
		// public static char toUpperCase(char ch):把给定的字符转换为大写字符
		System.out.println("toUpperCase:" + Character.toUpperCase('A'));
		System.out.println("toUpperCase:" + Character.toUpperCase('a'));
		System.out.println("-----------------------------------------");
		// public static char toLowerCase(char ch):把给定的字符转换为小写字符
		System.out.println("toLowerCase:" + Character.toLowerCase('A'));
		System.out.println("toLowerCase:" + Character.toLowerCase('a'));
	}
}

 Output:

isUpperCase:true
isUpperCase:false
isUpperCase:false
-----------------------------------------
isLowerCase:false
isLowerCase:true
isLowerCase:false
-----------------------------------------
isDigit:false
isDigit:false
isDigit:true
-----------------------------------------
toUpperCase:A
toUpperCase:A
-----------------------------------------
toLowerCase:a
toLowerCase:a

Exercise: alphabetic characters, lowercase alphabetic characters, number of numeric characters appear in uppercase a string of statistics. (Irrespective of other characters)
  
  : Analysis
         A: Define three statistical variables.
             bigCont = 0 int;
             int smalCount = 0;
             int numberCount = 0;
         B: a keyboard input string.
         C: Convert a string to an array of characters.
         D: traversing a character array for each character to obtain
         E: determining whether the character is a
             capital bigCount ++;
             lowercase smalCount ++;
             digital ++ numberCount;
         F.: Output to 

package cn.itcast_03;

import java.util.Scanner;

public class CharacterTest {
	public static void main(String[] args) {
		// 定义三个统计变量。
		int bigCount = 0;
		int smallCount = 0;
		int numberCount = 0;

		// 键盘录入一个字符串。
		Scanner sc = new Scanner(System.in);
		System.out.println("请输入一个字符串：");
		String line = sc.nextLine();

		// 把字符串转换为字符数组。
		char[] chs = line.toCharArray();

		// 历字符数组获取到每一个字符
		for (int x = 0; x < chs.length; x++) {
			char ch = chs[x];

			// 判断该字符
			if (Character.isUpperCase(ch)) {
				bigCount++;
			} else if (Character.isLowerCase(ch)) {
				smallCount++;
			} else if (Character.isDigit(ch)) {
				numberCount++;
			}
		}

		// 输出结果即可
		System.out.println("大写字母：" + bigCount + "个");
		System.out.println("小写字母：" + smallCount + "个");
		System.out.println("数字字符：" + numberCount + "个");
	}
}