Java基础程序

生兔子问题：

package com.atguigu.exer;

import java.util.Scanner;

public class Fibonacci {

    public static void main(String[] args) {
         Scanner scanner = new Scanner(System.in);
         System.out.println("Please input n:");
         int n = scanner.nextInt();
         
         System.out.println("当前值为" + fibonacci(n));
         
         int sum = 0;
         for(int i = 1; i <= n; i++){
             sum += fibonacci(n);
         }
         System.out.println(sum);
    }


    public static int fibonacci(int n){
        if(n < 2){
            return 1;
        }else {
            return fibonacci(n-1) +fibonacci(n-2);
        }
        
    }
}

统计字符个数：

package com.atguigu.exer;

public class total {
    public static void main(String[] args){
        String s = "aasddsfdg213SS";
        
        int countNum = 0;
        int countUpper = 0;
        int countLower = 0;
        int countOther = 0;
        
        for(int i = 0; i < s.length(); i ++){
            char c = s.charAt(i);
            
            if (c >= 'A' && c <= 'Z') {
                countUpper++;
            }else if (c >= 'a' && c <= 'z') {
                countLower++;
            }else if (c >= '0' && c <= '9') {
                countNum++;
            }else {
                countOther++;
            }
        }
        System.out.println(countLower);
        System.out.println(countUpper);
        System.out.println(countNum);
        System.out.println(countOther);
    }
    
}