[Java知识库]（Java）Character类

package com.book.lite;

import sun.lwawt.macosx.CSystemTray;

import java.util.Scanner;

/**
 * @author zhangyu
 * @date 2021年08月16日 10:50 下午
 * Character类的方法
 * 1.判断是否小写：isLowerCase()
 * 2.判断是否大写：isUpperCase()
 * 3.判断是不是数字：isDigit()
 *
 * 4.将字符转成大写：toUpperCase()
 * 5.将字符转成小写：toLowerCase()
 * 6.判断一个字符串中有多少个：大写字母，小写字母，数字，其他字符
 */
public class CharacterDemo {
    public static void main(String[] args) {
        System.out.println(methon_1('a'));
        System.out.println(methon_2('b'));
        System.out.println(methon_3('3'));
        System.out.println(methon_4('d'));
        System.out.println(methon_5('E'));

        /*
         * 从键盘获取字符串
         */
        Scanner sc = new Scanner(System.in);
        System.out.print("请输入字符串：");
        String s = sc.nextLine();
        methon_6(s);


    }
    public static boolean methon_1(char A){
        boolean a = Character.isLowerCase(A);
        return a ;
    }
    public static boolean methon_2(char B){
        boolean b = Character.isUpperCase(B);
        return b;
    }
    public static boolean methon_3(char C){
        boolean c = Character.isDigit(C);
        return c;
    }
    public static char methon_4(char D){
        char d = Character.toUpperCase(D);
        return d;
    }
    public static char methon_5(char E){
        char e = Character.toLowerCase(E);
        return e;
    }

    public static void methon_6(String s){
        int upper = 0;
        int lower = 0;
        int digit = 0;
        int other = 0;
        char[] ch = s.toCharArray();
        for (int x =0; x < ch.length ; x++){
            if (Character.isUpperCase(ch[x])){
                upper +=1;
            }

            else if (Character.isLowerCase(ch[x])) {
                lower += 1;
            }

            else if (Character.isDigit(ch[x])){
                digit +=1;
            }
            else {
                other +=1;
            }
        }
        System.out.println("大写字母有："+upper);
        System.out.println("小写字母有："+lower);
        System.out.println("数字有："+digit);
        System.out.println("其他字符有："+other);
    }
}

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