[JAVA] Enter the usage of System.in (Scanner) in Eclipse. (Learning and updating)

package z_Demo;
import java.util.Scanner;
public class demo {

	public static void main(String[] args) {
		System.out.println("1 --- 大叔");
		System.out.println("2 --- 阿姨");
		System.out.println("3 --- 小朋友");
		System.out.println("4 --- 哥哥");
		System.out.print("请选择：");
		Scanner in= new Scanner(System.in);
		if(in.hasNextInt()) // 做了一个判断，如果用户输入的不是整数，如：A，a，1.01等，会出现一个友情提示
		{
			System.out.println("您选择的是："+in.nextInt());
		}
		else {
			System.out.println("您输入了非法值：");
		}
	}
}

// =============== [Display character value]-[in.nextLine()]

Scanner in= new Scanner(System.in);
System.out.println("Your choice is: "+in.nextLine());

// =============== [Display value]-[in.nextInt()]

Scanner in= new Scanner(System.in);
        int num=in.nextInt()+1;
        String str=":"+num; // Convert the value to character
        System.out.println("Your choice is: " +str);
    

2. An example of entering two numbers step by step

package HELLO;
import java.util.Scanner;
public class input {

	public static void main(String[] args) 
	{
		
		System.out.print("输入乘数：");
		Scanner in_1= new Scanner(System.in);
		int in_11=in_1.nextInt();
		
		System.out.print("请输入被乘数：");
		Scanner in_2= new Scanner(System.in);
		int in_22=in_2.nextInt();
		
		int aaa=in_11*in_22;
		System.out.println(in_11+"*"+in_22+"="+aaa);
	}
	

 

3. Conditional judgment and evaluation of the input value

 

		System.out.print("请选择车型：1.金杯  2.金龙");
		m_input = input.nextInt();
		m_type=(m_input==1)?"金杯":"金龙";
	
		System.out.print("请选择车型：1.金杯  2.金龙");
		m_type=(input.nextInt()==1)?"金杯":"金龙";