How do I run code once every second in java?

Question

I have the following code, but I want it to run once every second, so if questNumber changes, then currentQuestStats will also change.

Editor's note: pastebin link with code that used to be here no longer works.

Answer 1

use ScheduledExecutorService which added in JAVA 5, you must import following classes.

import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

---

you can use it like below:

ScheduledExecutorService exec = Executors.newSingleThreadScheduledExecutor();
exec.scheduleAtFixedRate(new Runnable() {
    @Override
    public void run() {
        // TODO add your code here:
    }
}, 0, 1, TimeUnit.SECONDS);

---

Answer

• make a method called checkQuestNumber() in QuestsManagement class.
• also create a constructor for QuestsManagement
• initialize currentQuestStats with this value (§e§lCurrent quest: Kill 1 zombie).
• make currentQuestStats and questNumber private and encapsulate them.

here is your QuestsManagement after those changes

public class QuestsManagement {

    private String currentQuestStats = "§e§lCurrent quest: Kill 1 zombie";
    private int questNumber = 1;

    public String getCurrentQuestStats() {
        return currentQuestStats;
    }

    public int getQuestNumber() {
        return questNumber;
    }

    QuestsManagement() {
        ScheduledExecutorService exec = Executors.newSingleThreadScheduledExecutor();
        exec.scheduleAtFixedRate(new Runnable() {

            @Override
            public void run() {
               checkQuestNumber();
            }
        }, 0, 1, TimeUnit.SECONDS);
    }

    void checkQuestNumber() {

        if (questNumber == 1) {
            currentQuestStats = "§e§lCurrent quest: Kill 1 zombie";
            // change manual!
            questNumber = 2;
        } else if (questNumber == 2) {
            currentQuestStats = "§e§lCurrent quest: Walk 100 blocks";
            // change manual!
            questNumber = 1;
        }
    }
}

To Test Code!

in your custom command file

create an instance of QuestsManagement and use getCurrentQuestStats() method

QuestsManagement m = new QuestsManagement();
player.addChatMessage("Test" + QuestsManagement.getCurrentQuestStats());

Answer 2

Do it using multithreading. Here's the code:

public class QuestsManagement implements Runnable{
    public String currentQuestStats = "";
    public int questNumber = 1;
    Thread t;

    @Override
    public void run() {
        try {
            if(questNumber == 1) {
                currentQuestStats = "§e§lCurrent quest: Kill 1 zombie";
                if(questNumber == 2) {
                    currentQuestStats = "§e§lCurrent quest: Walk 100 blocks";
                }
            }
            Thread.sleep(1000);
        }
        catch(Exception e) {
            System.out.println(e);
        }
    }

    public static void main(String[] args) {
        Thread t = new Thread(new QuestsManagement());

        t.start();

        //do something else here... whatever you want to do
    }
}

Answer 3

First of all, you need to add all of the code you want to run to a method. I will assume you will call it update().

What you then want to do is add something like the following to your main program loop:

long nextTick = currentTimeMillis() + 1000 ;//Set time of first game tick

QuestsManagement quest = new QuestsManagement();

//Main Loop
while (true) {
    /*
    Do some other stuff
    */

    if (System. currentTimeMillis() >= nextTick) {//Check to see if it is time or past time to update
        nextTick += 1000//Set next tick to one second in the future
        quest.update();
    }
}

Please note that you are missing the update() method, the constructor, and any getters and setters. I would also refrain from making your variables public.

Answer 4

Well, there are multiple answers possible to this question. Java provides various ways to perform time operations. One approach is to use Timer class.

public class QuestsManagement {

public String currentQuestStats = "";
public int questNumber = 1;
static Timer t;
TimerTask task;
public static void main(String[] args) {
t = new Timer();
task = new TimerTask() {
        @Override
        public void run() {
            // TODO Auto-generated method stub

            if(questNumber == 1) {
                currentQuestStats = "§e§lCurrent quest: Kill 1 zombie";
            if(questNumber == 2) {
                 currentQuestStats = "§e§lCurrent quest: Walk 100 blocks";

         }
 } ;

t.scheduleAtFixedRate(task , 1000, 1000 );
}}

import following

import java.util.Timer;

import java.util.TimerTask;