Running a code called void, how do you run functions in delphi for example?

Question

Android

Hello everyone, how to run the code?

public static void main(String[] args) throws Exception {
       int c;
       String str = "btc.ru";
       URL hp = new URL(str);
       URLConnection hpCon = hp.openConnection();

       hpCon.setDoOutput(false);
       hpCon.setDoInput(true);
       hpCon.connect();
       InputStreamReader in = new InputStreamReader(hpCon.getInputStream());
       BufferedReader br = new BufferedReader(in);
       String line = "";
       System.out.print("Ok");
       while ((line = br.readLine()) != null) {
           System.out.println(line);

       }
   }

for example code

public void Message()
    {
       messagebox(123);
    }

I start by writing

protected void onCreate(Bundle savedInstanceState) {
        
           Message(); /////// это
    }

tried on advice

protected void onCreate(Bundle savedInstanceState) {
        main(); 
          
    }

highlights the brackets in red, I have never written in java, you can say, without a clue what, how, where
do you need to specify something in the brackets?
I'm trying to google the code that would write the website code into the string html variable so that it looks
something like this

public void Message() 
    {
String http = "";
http:=  send.get:= '123.ru';
      showmassage(http); // в переменной http код html страницы
    }

figurative code