KeyboardReader

import java.util.ArrayList;
import java.util.Scanner;

public class KeyboardReader implements Runnable {
    private ArrayList<String> arrayList = new ArrayList<>();

    @Override
    public void run() {
        try {
            Timer timer = new Timer("timer1", 5);
            Thread thread = new Thread(timer);

            thread.start();

            Scanner in = new Scanner(System.in);
            String currentMessage;
            int i = 0;
            while (true) {
                currentMessage = in.nextLine();
                arrayList.add(currentMessage);
                if (timer.isTimerOff()) {
                    System.out.println(arrayList.toString());
                    arrayList.clear();
                    timer.setProceedSecond(0);
                }
                if(i==1) {
                    thread.join();
                    i = 1;
                }
                System.out.println(timer.isTimerOff());
            }

        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public ArrayList<String> getArrayList() {
        return arrayList;
    }
}

TestTimer

import java.util.ArrayList;
import java.util.Scanner;

public class TestTimer {
    /*public static void main(String[] args) {
        Timer timer = new Timer("timer1", 10);
        Timer timer2 = new Timer("timer 2", 10);
        Timer timer3 = new Timer("timer  3", 10);
        Thread thread = new Thread(timer);
        Thread thread2 = new Thread(timer2);
        Thread thread3 = new Thread(timer3);

        thread.start();
        thread2.start();
        thread3.start();
    }*/

    public static void main(String[] args) {
        try {



            KeyboardReader keyboardReader = new KeyboardReader();
            Thread threadKey = new Thread(keyboardReader);

            threadKey.start();
            threadKey.join();

            /*ArrayList<String> arrayList = keyboardReader.getArrayList();
            for (String s : arrayList) {
                System.out.println(s);
            }*/
            System.out.println("End");
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

Timer

public class Timer implements Runnable {
    private String name;

    private int proceedSecond;
    private int generalSecond;
    private final long delay = 1000L;

    public Timer(String name, int generalSecond) {
        this.name = name;
        this.generalSecond = generalSecond;
    }

    @Override
    public void run() {
        while(!isTimerOff()) {
            //System.out.println(name + " : " + (generalSecond - proceedSecond));
            proceedSecond++;
            try {
                Thread.sleep(delay);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        //System.out.println(name + " has finished");
    }

    public boolean isTimerOff(){
        return proceedSecond == generalSecond ? true : false;
    }

    public void setProceedSecond(int proceedSecond) {
        this.proceedSecond = proceedSecond;
    }

}