public class HelloWorld{ //表示顶一个公开的类，起名HelloWorld
/*
public表示公开的
static表示静态的
void表示空
main表示方法名
String[] args 是一个main方法的形式参数列表
*/
public static void main(String[] args) {
System.out.println("Hello World");
}
} public means open
class means define a class
HelloWorld means a class name
public static void main (String [] args) // Define a public static main method, program entry
The java statement is terminated with a semicolon;
All strings in java need to be enclosed in double quotes
The difference between public class and class
* Multiple classes can be defined in a java source file
* A java source file does not necessarily have public class, public class is not necessary
* A class will be defined to generate a xxx.class bytecode file
* If a public class is defined in a java source file, there can only be one public class, and the class name must be the same as the java source file name.
