moka同学java学习笔记

package moka.hello;

public class HelloWorld {

    public static void main(String[] args){

//初始java

        int a = 1;

        int b = 3;

        int sum = a+b;

       

//if语句

        if(a<b){

            System.out.println(sum);

        }else{

            System.out.println("我要学java!"+sum);

        }

       

//for循环语句

        for(int i=1;i<sum;i++){

            System.out.println(a+sum);

        }

       

//运算表达式

        System.out.println((11+3*8)/4%3);

       

//if多重语句

        int age =70;

        if(age>=60){

            System.out.println("老年人");

        }else if(40 <= age && age <60){

            System.out.println("中年");

        }else if(18 <= age && age < 40){

            System.out.println("少年");

        }else{

            System.out.println("儿童");

        }

       

//if语句嵌套[要求：如果是周末晴天逛西湖，阴天室内玩，周内去上班]

        String today="周末";

        String wether="晴朗";

        if(today.equals("周末")){

            if(wether.equals("晴朗")){

                System.out.println("来杭州逛西湖！:):)");

            }else{

                System.out.println("室内玩桌游！");

            }

           

        }else{

            System.out.println("上班，来不了。:(");

        }

   

//if嵌套[要求：预赛成绩大于80分的进决赛，然后根据性别再划分男子组决赛和女子组决赛]

        int score = 94;

        String sex = "女";

        if(score >= 80){

            if(sex.equals("女")){

                System.out.println("女子组决赛");

            }else{

                System.out.println("男子组决赛");

            }

        }

       

//switch语句[根据考试的名次，给予前4名不同奖品，笔记本，IPAD2,移动电源，U盘]

        int rank = 3;

        switch(rank){

        case 1:

            System.out.println("第一名，奖励笔记本");

            break;

        case 2:

            System.out.println("第二名，奖励IPAD");

            break;

        case 3:

            System.out.println("第三名，奖励移动电源");

            break;

        default:

            System.out.println("其他，奖励U盘");

        }

//switch练习[如果是周一、三、五、早餐包子，二四六油条，周日主席套餐]

        char nowday='日';

        String x="吃包子";

        String y="吃油条";

        String z="吃主席套餐";

        switch(nowday){

        case '一':

        case '三':

        case '五':

            System.out.println(x);

        break;

        case '二':

        case '四':

        case '六':

            System.out.println(y);

        break;

        default:

            System.out.println(z);

        }

       

//while 循环[先判断，后执行]

        int i = 1;

        while(i<=10){

            System.out.println(i+"我在学java");

            i++;

        }

       

        for(i=1;i<=5;i++){

            System.out.println(i+"For循环");

        }

       

//do while 循环[先执行，后判断---》输出5次]

        int j =1;

        do{

            System.out.println("我要学java");

            j++;

        }while(j<=5);

// do while 计算50以内偶数的和

        int sum1 = 0;

        int num = 2;

        do{

            sum1 += num;

            num = num + 2;

        }while(num<=50);

        System.out.println("50以内的偶数之和："+sum1);

//[练习: 加法运算式]

        for(int a1=1,b1=5;a1<=b1;a1++,b1--){

            System.out.println(a1+"+"+b1+"="+(a1+b1));

        }

//[练习：计算1到100之间不能被3整除的数之和]

        int sum3 =0;

        for(int i3=1;i3<=100;i3++){

            if(i3 % 3 !=0){

                sum3 = sum3+i3;

            }

        }

        System.out.println("1-100不能被3整除的数之和："+sum3);

       

       

    }

      

   

}