Simple question about boolean expression

[Lisa Austin]

Hello everyone,

First time posting here and I'm very new to learning java. I have read through forums and I hope I'm using the code tag correctly here.
My question is regarding this snippet of code. The full code is after this. In this snippet how is the value of "length" being set or determined? I don't understand how we know if x is less than or greater than myDogs.length . I hope my question makes sense. This is from the Head First Java book , Chapter 3.

Thank You very much.

int x = 0;
while (x < myDogs.length){
myDogs[x].bark();
x = x + 1;
}

public class Dog{
String name;

public static void main (String[] args){

  Dog dog1 = new Dog ();
  dog1.bark ();
  dog1.name = "Bart";
  

  Dog[] myDogs = new Dog[3];

  myDogs[0] = new Dog();
  myDogs[1] = new Dog();
  myDogs[2] = dog1;

  myDogs[0].name = "Fred";
  myDogs[1].name = "Marge";

  System.out.print("last dog's name is");
  System.out.println(myDogs[2].name);

  int x = 0;
  while(x < myDogs.length) {
   myDogs[x].bark();
   x = x + 1;
   }
  }
  public void bark () {
   System.out.println(name + " says Ruff!");
   }
   public void eat () {  }
   public void chaseCat() { }
  }

[Henry Wong]

Lisa Austin wrote:In this snippet how is the value of "length" being set or determined? I don't understand how we know if x is less than or greater than myDogs.length.

In Java, arrays have a length field which is the size of the array. It is set when the array is instantiated.

Henry

[Ashwin Rao]

Here you create an array: Dog[] myDogs = new Dog[3];
Arrays have some built-in superpowers!
"length" is one of them. This "length" variable stores the max. length of the array. In this case it stores 3.

int x = 0;
while (x < myDogs.length){ // In this statement you compare the current value of x (which is 0 the first time, 
//1 the second time and so on) with 3 i.e value of length variable for myDogs array.
  myDogs[x].bark();
  x = x + 1;
}

[fred rosenberger]

also. the length of the array is not how many things are IN it, but simply how many it can hold.

Just like an egg carton...it can have twelve spots for eggs, but any/all of those spots can be empty. But the size/length of it will always be 12.

[Lisa Austin]

Thank You everyone! This really helped me.