When I first contacted Java, I created a project but found that the class name is an illegal identifier @Illegal identifier

Create the first Java project: Hellow World

It displays Type name is not valid. The type name ‘Hello World’ is not a valid identifier. After searching for the problem, I found that there is a space in the name of Hellow World.A legal identifier cannot be mixed with spacesof.

Later, a cross was found in the upper part of the code block, which read: "Must declare a named package because this compilation unit is associated to the named module ‘HelloWorld’"

I found a solution by searching the blogs of big guys:What to do if the package is not declared

For Java novices who use the latest version of eclipse, they may encounter a small problem:
“ Must declare a named package because this compilation unit is associated to the named module ‘MyProject02’ ”
The reason for this situation is that in the latest version of eclipse, you need to define a package while defining a class. This is different from the previous eclipse, and many java instructional videos still use the non-latest version of ecilpse , So we see in many teaching videos that the teacher can directly create a class. Here, let me say by the way how to define a package:
Select the File->New->Class command in the eclipse menu bar, in the import dialog box, search for Package, and then name it.
From the blogger-DSB kid

The first time I came into contact with java, there were always many problems. After typing the code, I found

The problem of The public type c must be defined in its own file occurs because the defined JAVA class is inconsistent with the file name;
Solution:JAVA error: The public type *** must be defined in its own file***
　　 1. Modify the file name to the same name as the public class;
　　2, modify the class name to the same file name;
　　3. When the subclass inherits the parent class, there is no need to use public modification
From the blogger-Data circle

Then I took a closer look at my class name and file name, and found that HelloWorld was entered as HellowWorld by me. I did not find the problem after reading it for a long time. It seems that the code is still not sensitive enough...

After running the program, you can output the page to get the content in the quotes of System.out.println
This is the first project I created: HelloWorld