Clocker class and main

package MyClock;

public class Clocker {
    private int hours, minutes;
    private final int max_hours = 24, max_minutes = 60, min_value =  0;
    private static int format = 24;//default format

    public Clocker(int hours, int minutes) {
        this.setHours(hours);
        this.setMinutes(minutes);
    } //main constructor

    public Clocker(Clocker object) {
        this.hours = object.getHours();
        this.minutes = object.getMinutes();
    }  // cloning constructor

    public Clocker() {
        this(0, 0);
    } //constructor for cases we build an empty object

    public boolean setHours(int hours) {
        if (hours <= min_value || hours > max_hours) {
            this.hours = min_value;
            return false;
        } else {
            this.hours = hours;
            return true;
        }
    }

    public boolean setMinutes(int minutes) {
        if (minutes <= min_value || minutes > max_minutes) {
            this.minutes = min_value;
            return false;
        } else {
            this.minutes = minutes;
            return true;
        }
    }

    public int getHours() {
        return hours;
    }

    public int getMinutes() {
        return minutes;
    }

    /***
     *
     * getFormat and setFormat will be static because of the parameter "format" is static
     */
    public static boolean setFormat(int format) {
        if (format != 12 && format != 24) {
            Clocker.format = 0;
            return false;
        }
        Clocker.format = format;
        return true;
    }

    public static String getFormat() {
        return format == 12 ? "am:pm format" : "24 hours format";
    }

    @Override
    public String toString() {
        if (format == 12) {
            return (hours < 10 ? "0" : "") + (hours == 12 ? hours : hours % 12) + ":" + (minutes < 10 ? "0" : "") + minutes + (hours < 12 ? "am" : "pm");  //in case of am:pm format it will write am or pm in the end of the string
        }else {
            return (hours < 10 ? "0" : "") + hours + ":" +(minutes < 10 ? "0" : "")+ minutes; // if an hour is until 10 it will write 0 at
        }
    }
}



=======================================================================================================================================
import java.util.*;
import MyClock.*;
public class objectsClassesFirstLesson {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.println("Plese write 12 for am:pm format or 24 for 24 format:");

        //we can use format before we do any object of class
        Clocker.setFormat(sc.nextInt());

        // new object of class
        Clocker shaon = new Clocker(12, 30);

        // see it prints right
        System.out.println(shaon + " " + shaon.getFormat());

        // using cloner constructor
        Clocker chas = new Clocker(shaon);

        // change the time of first object
        shaon.setHours(0);
        shaon.setMinutes(56);

        // checking cloner constructor works
        System.out.println(shaon + " " + shaon.getFormat());
        System.out.println(chas + " " + chas.getFormat());
    }
}