does a java class need a constuctor?

[vb_student]

does a java class need a constructor, in this code there does not seem to be any constructor?

class CheckingAccount {

   private double balance = 0;
   public void setBalance(double bal) {
      balance = bal;
   };

   public double getBalance(){

      return balance;
   };
}


class Encapsulation {

   public static void main(String args[]) {
      System.out.println("Starting myEncapsulation...");
      CheckingAccount myAccount = new CheckingAccount();
      myAccount.setBalance(40.00);
      System.out.println("Balance = " + myAccount.getBalance());
   }
}

in the code line

checkingaccount myaccount = new checkingaccount();

does the checkingaccount() call a function or does it call the class since there is a pari of brackets at the end of the code

[CornedBee]

If no constructor at all is defined, the compiler will implicitly define one that takes no arguments and does nothing except inline initializations.

[vb_student]

thanks for the reply

what is an inline initialisation

what about if no destructor is defined?

in the code line

checkingaccount myaccount = new checkingaccount();

does the checkingaccount() call a function or does it call the class since there is a pari of brackets at the end of the code

[ComputerJy]

Again as CornedBee said, it'll call the no-arguments constructor, if you didn't create one, java will do that.
In-line initialization is calling the constructor of the super class and allocating memory for the attributes and function

EDIT: Java doesn't have a "destructor" you can override the "finalize()" method

[CornedBee]

Actually, by in-line I meant stuff like this:

public class Whatever
{
  int i = 100;
}

but what ComputerJy said applies too, of course. Except for the allocating memory stuff: memory for the attributes is already allocated by the time the constructor is called, and functions don't take memory.

[vb_student]

thanks for the replies guys, it makes sense



can i break the following code

checkingaccount myaccount = new checkingaccount();

into

checkingaccount myaccount ;
myaccount = new checkingaccount();

[ComputerJy]

If you try it and it works then it's ok to do so.
Yes its ok to do it

[vb_student]

thanks for the reply

the superclass is the base class, right?

what attributes and methods does the superclass contain?

in the code

checkingaccount myaccount = new checkingaccount();

isnt't the constructir returning an address which is assigned to the object myaccount?

or is it the keyword new which is returning the address?

[ComputerJy]

Depends on the super class you are deriving from, if it's nothing (class Object implicitly), read javadoc for more information

[CornedBee]

The keyword new returns the reference (there's no such thing as raw addresses in Java). The constructor call initializes the object.

[vb_student]

thanks guys
makes sense