java基础练习[一]

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);
       
       
    }

      
   
}