Day04-the first Java program, IDEA installation

Day04-the first Java program, IDEA installation

Hello World

1. Create a new txt file --> rename it to Hello.java (the name is consistent with the class name class)
2. Edit with notepad++
3. Write code

public class Hello{
    
    
    public static void main(String[] args){
    
    
        System.out.print("Hello World!");
    }
}

4. Enter cmd + "space" at the beginning of the file address bar (enter the directory where the file is located in cmd)
5. Compile and enter "javac Hello.java" (ie javac + space + file name. extension)
6. Run , enter "java Hello", and press Enter

Precautions:

• Capitalization issues (String and System are capitalized)
• All symbols use English half-width
• The file name is consistent with the class name (the first letter is capitalized)

Compiled, interpreted

• Compilation type: compile all at once, and then run

  After the code changes, you need to recompile all

• Interpretation: compile one sentence and run one sentence

  Code execution efficiency is low, suitable for websites, etc.

IDEA

IDE: Integrated Development Environment (IDE, Integrated Development Environment) is an application used to provide a program development environment, which generally includes tools such as a code editor, a compiler, a debugger, and a graphical user interface. Integrated development software service suite with code writing function, analysis function, compilation function, debugging function, etc.

Common abbreviations and abbreviations:

• psvm = public static void main(String[] args){}

• sout = System.out.println();