go学习开篇

package main
 
import "fmt"
 
func main() {
    // 单行注释
    /*
      多行注释
     */
 
   fmt.Println("Hello, World!")
}

go run: cannot run non-main package

# command-line-arguments
./hello_world.go:4: imported and not used: "flag"

# command-line-arguments
runtime.main: call to external function main.main
runtime.main: main.main: not defined
runtime.main: undefined: main.main

xxx {
     yyyy
}

# command-line-arguments
./hello_world.go:6: syntax error: unexpected semicolon or newline before {

public class Test {
 
    public static void main(String args[]) {
        System.out.println("hello world !");
    }
 
}