Time in Java counting seconds in real time

Question

I want to show the system time and the seconds counting in real time in Java.

Answer 1

You can use the Java service scheduler to display the hours every second.

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.*;

public class Relogio {

    public static void main(String args[]) throws IOException {

        ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);

        scheduler.scheduleAtFixedRate(
          new Runnable() {
              public void run() {
                  System.out.println(new SimpleDateFormat("HH:mm:ss").format(new Date()));
              }
        }, 1, 1, TimeUnit.SECONDS);
    }
}

No need to use the class Thread, or use the method sleep and nor do incorrect treatment of exception.

Answer 2

According to that response in the OS you can do it like this:

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Main {
    public static void main(String[] args) {
        Thread th = new Thread(new Runnable() { //cria uma thread
            public void run() {
                while(true) { //roda indefinidamente
                    Date date = Calendar.getInstance().getTime(); //pega a hora do sistema
                    DateFormat formatter = new SimpleDateFormat("HH:mm:ss");
                    String today = formatter.format(date);      
                    System.out.println(today);
                    try {
                        Thread.sleep(1000); //espera 1 segundo para fazer a nova evolução
                    } catch(InterruptedException ex){
                        //é algo terrível a se fazer mas pelo jeito a API medonha do Java exige
                    }
                }
            }
        });
        th.start();
    }
}

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

It may not give the best result but that’s it. There are no guarantees that all screen updates will occur every exact 1 second.

It has to position the cursor always in the same position but as I have no way to test I will just leave the code for you to try:

System.out.print(String.format("%c[%d;%df", 0x1B, 0, 0));

Answer 3

I think this is what you want

import java.text.SimpleDateFormat;
import java.util.Date;
import javax.swing.JLabel;

public class relogio {

    public static void main(String[] args) {
        try {  
            while (true) {  
                Date d = new Date();  
                StringBuffer data = new StringBuffer();  

                    SimpleDateFormat sdfData = new SimpleDateFormat("dd.MM.yyyy");  
                    data.append(sdfData.format(d));  
                    data.append(" - ");  

                SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");  
                System.out.println(""+data.toString() + sdf.format(d));

                Thread.sleep(1000);  
            }  
        } catch (InterruptedException ex) {  
            System.out.println("Problema na atualização da data/hora");  
            ex.printStackTrace();  
        }  
    }
}