Java study notes 1 - Java catalog creation process and input and output

Java study notes 1 - Java catalog creation process and input and output

1. Create a program

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​Then a window appears, just name it and add the option of sring[]

2. Input and output

package hello;

import java.util.Scanner;

public class Hello {

    public static void main(String[] args) {
        // TODO Auto-generated method stub 
        System.out.println("Hello World!");  //输出语句
        Scanner in = new Scanner(System.in); //输入语句
        System.out.println(in.nextLine());   //将输入的输出
    }

}

System.out.println("echo:" + in.nextLine());     //输出的简单语法
System.out.println("2+3="+5);    //输出5 正确
System.out.println("2+3="+2+3);  //输出23 错误 如需改正，需要加上括号 +（2+3）即可
//但是如果2+3在前面时，的输出是5

3. Pay attention to the realization

• Do not run multiple programs when running, otherwise it will increase the burden on the computer
• Press shift + down arrow key to select multiple lines
• ctrl + / to realize the comment of the selected line, or to clear the comment
• Every time in.nextInt() reads an integer