Please help me!!! I'm stuck in the abstract classes

Question

Hello everybody,

Currently i'm trying to complete the online JAVA course on MOOC.FI and i'm complete lost in the following syntaxes:

How they switched the following code :

public class Main{
public static void main(String args[]){

ClockHand hours = new ClockHand(24);
ClockHand minutes = new ClockHand(60);
ClockHand seconds = new ClockHand(60);

while (true) {
// 1. Printing the time
System.out.println(hours + ":" + minutes + ":" + seconds);

// 2. Advancing the second hand
seconds.advance();

// 3. Advancing the other hands when required
if (seconds.value() == 0) {
minutes.advance();

if (minutes.value() == 0) {
hours.advance();
}
}
}
}
}

public class ClockHand {
private int value;
private int limit;

public ClockHand(int limit) {
this.limit = limit;
this.value = 0;
}

public void advance() {
this.value = this.value + 1;

if (this.value >= this.limit) {
this.value = 0;
}
}

public int value() {
return this.value;
}

public String toString() {
if (this.value < 10) {
return "0" + this.value;
}

return "" + this.value;
}
}

to this one :

public class Main{

public static void main(String args[]){

Clock clock = new Clock();

while (true) {
System.out.println(clock);
clock.advance();
}
}
}

public class Clock {
private ClockHand hours; // what does it mean this???
private ClockHand minutes;
private ClockHand seconds;

public Clock() {
this.hours = new ClockHand(24); // what does it mean this???
this.minutes = new ClockHand(60);
this.seconds = new ClockHand(60);
}

public void advance() {
this.seconds.advance();

if (this.seconds.value() == 0) {
this.minutes.advance();

if (this.minutes.v

Answer 1

The first //what : Initial a ClockHand variable.

Second //what : In this function, the previous variable is assign to a new obj of type ClockHand.

Answer 2

The first what: the variable shoudn t be initialize with types?(int, String erc)
Why they initialize with Private ClockHand hours instead of int hours?