Conditional judgment and practice of loop sentences

1. Conditional judgment statement

1.1 Practice of if-else statement

1.1.1 Topic: Yue Xiaopeng took the Java exam. He and his father Yue Buqun reached a promise: If: When the score is 100 points, a BMW will be awarded; when the score is (80,99), an iphone xs max will be rewarded; When it is [60,80], an iPad will be awarded; otherwise, there will be no reward. Please input Yue Xiaopeng’s final grades from the keyboard and judge

//导包
import java.util.Scanner;
public class scoreTest{
    public static void main(String args[]){
        //创建键盘录入对象
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入岳小鹏的Java考试成绩");
           //接收数据
           int score = scanner.nextInt();
           //if - else 条件判断
           if(Score == 100){
                System.out.println("奖励一辆BMW");
            }else if(score >80 && Score<= 90){
                System.out.println("奖励一台iPhone xs max");
            }else if(score >=60 && score <= 80){
                System.out.println("奖励一个iPad");
            }else{
                System.out.println("没有获得任何奖励");    
            }
    }
}

1.1.2 Topic: Input three integers from the keyboard and store them into variables num1, num2, num3, sort them (using if-else if-else), and output them from small to large.

//导包
import java.util.Scanner;
//  由键盘输入三个整数分别存入变量num1、num2、num3， 对它们进行排序(使用 if-else if-else),并且从小到大输出。
public class Test {
	//main方法
	public static void main(String[] args) {
		//创建键盘录入对象
		Scanner scanner = new Scanner(System.in);
		System.out.println("请输入第一个整数：");
		int num1 = scanner.nextInt();
		System.out.println("请输入第二个整数：");
		int num2 = scanner.nextInt();
		System.out.println("请输入第三个整数：");
		int num3 = scanner.nextInt();
		//if - else语句
		if(num1>num2) {
			if(num2>num3) {
				System.out.println("从小到大第一个数是:"+num3+"第二个数是："+num2+"第三个数是:"+num1);
			}
		}else if(num2 > num3){
			System.out.println("从小到大第一个数是:"+num3+"第二个数是："+num1+"第三个数是:+num2);
		}else {
			System.out.println("从小到大第一个数是:"+num1+"第二个数是："+num2+"第三个数是:"+num3);
		}	
	}

1.2. Practice of switch statement

1.2.1 Topic: Enter the corresponding number in the keyboard to enter the number, and give the number in English

import java.util.Scanner;
//输入对应数字，给出数字的英文
public class Test1 {
	//main方法
	public static void main(String[] args) {
	Scanner scanner = new Scanner(System.in);
	System.out.println("请输入数字：");
	int number = scanner.nextInt();
		switch(number) {
			case 0:
				System.out.println("zero");
				break;
			case 1:
				System.out.println("one");
				break;
			case 2:
				System.out.println("two");
				break;
			case 3:
				System.out.println("three");
				break;
			case 4:
				System.out.println("four");
				break;
			case 5:
				System.out.println("five");
				break;
			case 6:
				System.out.println("six");
				break;
			case 7:
				System.out.println("seven");
				break;
			case 8:
				System.out.println("eight");
				break;
			case 9:
				System.out.println("nine");
				break;
			default:
				System.out.println("输入有误：");
				break;
		}	
	}
}

1.2.2 Topic: Keyboard input seasons, output scenarios corresponding to the seasons

//键盘录入季节，输出对应季节的情景
import java.util.Scanner;
public class Test2 {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		System.out.println("请输入季节");
		String season = scanner.nextLine();
		switch(season) {
		case "春":
			System.out.println("生机勃勃");
			break;
		case "夏":
			System.out.println("烈日炎炎");
			break;
		case "秋":
			System.out.println("秋高气爽");
			break;
		case "冬":
			System.out.println("寒风凛冽");
			break;
			default:
				System.out.println("输入错误！");
				break;
		}
	}
}

2. Loop statement

2.1. for loop exercise

2.1.1 Topic: Output from 1 to 100

public class Test3 {
	public static void main(String[] args) {
		for(int x = 1;x<=100;x++) {
			System.out.println(x);
		}
	}
}

2.1.2 Topic: Calculate the result of 1+2-3+4-5+6-7...+100

public class Demo01 {
	public static void main(String[] args) {
		int sum1 = 0;//偶数之和
		int sum2 = 0;//奇数之和
		for(int a = 0;a<=100; a++) {
			if(a %2 == 0) {
				sum1 +=a ;
			}else if(a %2!= 0) {
				sum2 -= a;
			}
		}
		System.out.println(sum1+sum2);
	}
}

2.2 while loop exercise

2.2.1 Topic: Use the while loop to output HelloWorld 10 times

public class Demo{
    public static void main(String args[]){
        int x = 1;
        while(x<10){
            System.out.println("HelloWorld");
            x++;
        }
    }
}

2.2.2 Topic: Use the while loop to find the sum between 1 and 100

public class Demo{
    public static void main(String args[]){
        int sum = 0;
        int x = 1;
        while(x<100){
            sum +=x;
            x++;
        }
        System.out.println("和为"+sum)；
    }   
}

2.3 do-while loop exercise

2.3.1 Topic: Use do-while loop to output HelloWorld 10 times

public class Demo{
    public static void main(String args[]){
        int x = 1;
        do{
            System.out.println("HelloWorld");
            x++;
        }while(x<10);
    }
}

Java Basics-4