Day02

Demo01

​
package com.Day02;

import java.sql.SQLOutput;
import java.util.Scanner;

/**
 * @Description $
 * @Param $
 * @Return $
 * @Author Xiao DaChen
 * @Date $
 * @Time $
 */
public class Demo01 {
    public static void main(String[] args) {
        //Scanner
        //创建一个扫描对象，用于接收键盘数据
        Scanner scanner = new Scanner(System.in);

        System.out.println("使用next方式接收：");
        //判断用户有没有输入字串
        if (scanner.hasNext() == true){
            String str = scanner.next();
            System.out.println("输入的内容是"+str);
        }
        //不可以输入空格
        //使用next方式接收：
        //dsr  534 g
        //输入的内容是dsr

        //关闭
        scanner.close();
    }
}

​

Demo02

package com.Day02;

import java.util.Scanner;

/**
 * @Description $
 * @Param $
 * @Return $
 * @Author Xiao DaChen
 * @Date $
 * @Time $
 */
public class Demo02 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.println("Place input your number:");

        String input = scanner.nextLine(); //可以输入空格

        //Place input your number:
        //342352   543543643
        //Number is 342352   543543643

        System.out.println("Number is " + input);
    }
}

Demo03

package com.Day02;

import java.util.Scanner;

/**
 * @Description $
 * @Param $
 * @Return $
 * @Author Xiao DaChen
 * @Date $
 * @Time $
 */
public class Demo03 {
    public static void main(String[] args) {

        double sum = 0;
        int num = 0;

        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextDouble()){
            double x = scanner.nextDouble();
            sum+= x;
            num++;
            System.out.println("您输入的数字是"+sum);
            System.out.println("现在有"+num+"个数字");
        }

        System.out.println(num+"个数字的和是"+sum);
        System.out.println(num+"个数的平均数是"+sum/num);

        scanner.close();
    }
}

Demo04

package com.Day02;

/**
 * @Description $
 * @Param $
 * @Return $
 * @Author Xiao DaChen
 * @Date $
 * @Time $
 */
public class Demo04 {
    public static void main(String[] args) {
        /*
        while(布尔表达式 ){
                //是真会一直执行下去
        }
         */

        //少数情况需要一直执行，比如服务器的请求响应监听
        int num = 0;
        int sum = 0;
        while (num<=100){
            sum = sum + num;
            num= num + 1;
            System.out.println(sum);
        }
    }
}

Demo05

package com.Day02;

/**
 * @Description $
 * @Param $
 * @Return $
 * @Author Xiao DaChen
 * @Date $
 * @Time $
 */
public class Demo05 {
    public static void main(String[] args) {
        int ji = 0;
        int ou = 0;

        //练习1 计算0-100之间奇数和和偶数和
        for(int i = 0;i<=100;i++){
            if(i % 2 == 0){
                ji = ji + i;
            }else {
                ou = ou + i;
            }
        }
        System.out.println("偶数和是"+ou);
        System.out.println("奇数和是"+ji);

    }
}

Demo06

package com.Day02;

/**
 * @Description $
 * @Param $
 * @Return $
 * @Author Xiao DaChen
 * @Date $
 * @Time $
 */
public class Demo06 {
    public static void main(String[] args) {
        //练习2 用while或者for循环输出1-1000之间能被5整除的数，并且每行输出3个
        int j = 1;
        int temp = 0;
        //没有一行输出，三行之后隔一行

        while (j<=1000){
            if (j % 5 == 0){
                System.out.print(j+"\t");
                temp++;
                if (temp == 3){
                    System.out.println();
                    temp = 0;
                }
            }
            j++;
        }
        System.out.println("wile循环结束");
    }
}

Demo07

package com.Day02;

/**
 * @Description $
 * @Param $
 * @Return $
 * @Author Xiao DaChen
 * @Date $
 * @Time $
 */
public class Demo07 {
    public static void main(String[] args) {

        //打印九九乘法表
        for (int i = 1;i <= 9;i++){
            for (int j = 1;j <= i;j++){
                System.out.print(j+"*"+i+"="+i*j+"\t");
            }
            System.out.println();
        }
        System.out.println("for循环结束");
    }
}

Demo08

package com.Day02;

/**
 * @Description $
 * @Param $
 * @Return $
 * @Author Xiao DaChen
 * @Date $
 * @Time $
 */
public class Demo08 {
    public static void main(String[] args) {
        //打印三角形
        //首先打印一个5行三角形
        for (int i = 1; i <= 5; i++) {
            for (int j = 5; j >= i ; j--){
                System.out.print(" ");
            }
            for (int j = 1;j<=i;j++){
                System.out.print("*");
            }
            for (int j = 1;j < i;j++){
                System.out.print("*");
            }
            System.out.println();
        }
    }
}