set clock

import java.time.LocalTime;
import java.util.*;

public class Main {

    public static void main(String[] args) {

        List<Clock> clockList = Clocks.init();
        print(clockList);
        addMinute(clockList ,1);
        System.out.println();
        print(clockList);
    }

    private static void print(List<Clock> clockList) {
        for (Clock item : clockList) {
            System.out.println(item);
        }
    }

    private static List<Clock> addMinute(List<Clock> clocks, int minute) {
        for (Clock item : clocks) {
            item.addMinutes(minute);
        }
        return clocks;
    }
}

class Clock {

    private LocalTime time;
    private int hour;
    private int minute;

    public Clock(LocalTime time) {
        this.time = time;
    }

    public Clock addMinutes(int minute) {
        time = time.plusMinutes(minute);
        return new Clock(time);
    }

    @Override
    public String toString() {
        return "Godzina: " + time;
    }
}

class Clocks {

    private static final Random random = new Random();
    private static List<Clock> clocksList;
    private static Clock randomClock() {
        int randomHour = random.nextInt(23);
        int randomMinute = random.nextInt(59);
        return new Clock(LocalTime.of(randomHour, randomMinute));
    }

    public static List<Clock> init() {
        clocksList = new LinkedList<>();
        int clocksSize  = random.nextInt(5) + 2;
        for (int i = 0; i < clocksSize; i++) {
            clocksList.add(randomClock());
        }
        return clocksList;
    }
}

I found such a solution on the internet but I don't understand what the linkedlist structure looks like because it is randomly generated I have to do a similar task but I wanted to use my own fixed list, can you explain this to me? actually I would like to understand it in these two ways

import java.util.*;

class Clock {

    private int hour;
    private int minute;

    public Clock(int hour, int minute) {
        this.hour = hour;
        this.minute = minute;
    }
    public int addMinutes(int minute) {
            minute = minute + 1;
            return minute;
        }
        public int minuteChceck() {
            while (minute == 60) {
                hour = hour + 1;
            } return hour;
        }
    @Override
    public String toString() {
        return "Godzina: " + hour +":"+ minute;
    }
}

public class Program {
    public static void main(String[] args) {
        LinkedList<Clock> clocks = new LinkedList<>();
        clocks.add(new Clock(10, 20));
        clocks.add(new Clock(19, 59));


        System.out.println(clocks);
    }
}

I tried something like this, but as it happens with time 59 + 1 minute, it should not display 60 minutes: D

import java.util.concurrent.TimeUnit; class Clock { public String city; private int hour; private int minute; private int second; public Clock(String city, int hour, int minute, int second) { this.city = city; this.hour = hour; this.minute = minute; this.second = second; } public void tick() { // approach using modulus if ((second = ++second % 60) == 0) if ((minute = ++minute % 60) == 0) hour = ++hour % 24; // approach using conditional statements /* if (++second > 59) { second = 0; if(++minute > 59) { minute = 0; if (++hour > 23) hour = 0; } } */ } @Override public String toString() { /* return "Godzina in " + city + ": " + (hour < 10 ? "0" + hour : hour) + ":" + (minute < 10 ? "0" + minute : minute) + ":" + (second < 10 ? "0" + second : second); */ // or use String.format return String.format("Godzina in %s: %02d:%02d:%02d", city, hour, minute, second); } public static void main(String[] args) throws InterruptedException { Clock clock = new Clock("Nuremberg", 9, 59, 55); for (int i = 0; i < 10; i++) { clock.tick(); System.out.println(clock); TimeUnit.SECONDS.sleep(1); } } }

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Lisa L

Level 47 , Nuremberg, Germany

1 June 2022, 11:57

That LinkedList is just a List, similar to ArrayList. It's additional features aren't used here. So you simply could replace it with the mentioned ArrayList. The purpose of the Clocks class... it's some kind of factory class, some generator. It generates random Clock objects and adds them to a list. That's all. It adds between 2 and 6 clocks to the list. Have a look at this sample clock class, I added seconds and a tick method

Karol Grzeszczak

Level 31 , Poland, Poland

2 June 2022, 04:21

yes, I guess it's a normal list, but when I wanted to enter something into it, I didn't know if the time is 1222 or e.g. 12.22 I meant more about the construction in this list, in your example it is clear :) but in this with random generated clocks it's not

2 June 2022, 08:04

such inconsistencies are hard for me, that's why I ask :)

2 June 2022, 11:07

The Clock class you posted is taking using LocalTime objects. That's a class working like a clock. So the programmer wrapped a clock inside a Clock class. You can look up how LocalTime is working in the api docs. No magic here. So when you create a Clock object 'manually', outside the generator class you need to pass it a LocalTime object. That is done as shown in the Generator... new LocalTime(hour, minute); The problem you may face is the fact that LocalTime objects are immutable (like Strings). Means you can not modify those objects. Instead the class returns a new object (just look at the add method, it returns a new Clock object). In the Clocks class you have two methods, one that creates a random Clock object (holding a LocalTime object) and the init method that initilaizes a List with a random number of Clocks. To add these random number of clocks it uses the previously mentioned randomClock method. No problem here so far. The init method returns the list of clocks. You can save it in a List<Clock> variable. That'll be better for testing. To that list you can add new Clock objects that you create list.add(new Clock(new LocalTime(10, 45))); But keep in mind that these objects are immutable. If you loop over the list and call the addMinute method on each element (Clock incrMinuteClock = clock.addMinutes(1); // that's how you need to use it and then output the incrMinuteClock object to see the increase time), then the objects in the list do not change. If you loop over them again the still have the old value. But I thought you're working your 'own' Clock class and do not want to use the found one?

3 June 2022, 04:53

as I said, I just wanted to understand it and you explained it to me beautifully :) Thank you :) but yes i made my own, so you thought right :) I wanted to analyze it when I have more time