Hama Kamal

Seetharaman Venkatasamy wrote:

Hama Kamal wrote:do you mean that da[0] refers to two objects?

It is a chaining, da[0] referes Dozens object, which internally referes []dz object. clear now?

Seetharaman what you say is quite reasonable and logical but i want to ask if it is your own conclusion or you got if from a text book?

First superclass in the hierarchy of the serializable class that does not implements Serializable interface, MUST have a no-arg constructor.
If this is violated, readObject() will produce a java.io.InvalidClassException in runtime.

can you give an example for this one?!

n nandwana wrote:

Yohan Weerasinghe wrote:I have brought this book

Yes this is a good book, but if you feel it's being tough for you than you can also try book by Khalid&Mughal SCJP 6.

is the new version of this book released? scjp7?

Seetharaman Venkatasamy wrote:

Hama Kamal wrote:are you sure that at line 2 two objects are created?

array int[] is an object. when Dozens object get initialized, it initialized an object []dz of type int array. what do you think?

well i think there is only one Object and it's referenced from da[0],,,, do you mean that da[0] refers to two objects?

Seetharaman Venkatasamy wrote:Well, Actually there are 5 objects created, and only 1 object is eligible for GC.
Dozens[] da=new Dozens[3];//one object because, it wont run Dozens's constructor da[0]=new Dozens();//2 objects one is new Dozens() and this new runs Dozens's constructor, so []dz created Dozens d=new Dozens();--> (0) //2 objects one is new Dozens() and this new runs Dozens's constructor, so []dz created da[1]=d; d=null;//d points to null, so it released new Dozens();--> (0) da[1]=null; //d[1]points to null, so it released new Dozens();--> (0) now(in this line) it dont have reference, hence eligible for GC
Note* but end of the method , all the above 5 objects will be Garbage Collected.

are you sure that at line 2 two objects are created?

la fyuan wrote:Given:
public class Eggs { public static void main(String[] args) { Dozens[] da=new Dozens[3]; // first object is created here da[0]=new Dozens(); // second object got created Dozens d=new Dozens(); // third object got created da[1]=d; // 1 d=null; // 2 da[1]=null; //3 // as a result of line 1,2 and 3 one object is eligible for GC here } } class Dozens{ int []dz={1,2,3,4,5}; // fourth object got created however i'm not so sure about this one.. :-( }

Question:
How many objects were created?
How many object(objects) is(are) eligible for GC?

Loganathan Karunakaran wrote:Today I saw that Java 7 beta exams are added in the Oracle's Certification Pages. Just thought of sharing it:

http://education.oracle.com/pls/web_prod-plq-dad/db_pages.getpage?page_id=505





Regards
Loganathan

is the K&B book updated as well? if so where can i get it?

n nandwana wrote:Can anyone tell me, what is major difference between them, till now i was preparing for 1.6 through "SCJP 1.6 Study Guide by K&B", now what should i do ? Can anyone tell me book for 1.7 ? now , Is OCA mandatory for OCJP 1.7 ?

is SCJP 1.7 realease?

Question:
How many objects were created?
How many object(objects) is(are) eligible for GC?

4
1

hi all,

i'm supposed to get the result in italian when i run below code but i get it in eglish,,, any idea?

import java.text.*; import java.util.*; class TestDates { public static void main(String[] args) { Locale loc = new Locale("it", "IT"); Calendar c = Calendar.getInstance(loc); c.add(Calendar.MONTH, -3); Date d = c.getTime(); String s = d.toString(); System.out.println(s); } }

Many thanks Tommy

Thansk Tommy, but are you sure that it is not on the exam?

well John, and on which object the private methods get called ? on the Dog object ?

how good are you in java? it depends on your background and experience

hi guys...
please check my comment below line 20
shouldn't we get NullPointerException, since theCollar has not been initialized yet???
import java.io.*; class Collar { private int collarSize; public Collar(int size) { collarSize = size; } public int getCollarSize() { return collarSize; } } class Dog implements Serializable { transient private Collar theCollar; // we can't serialize this private int dogSize; public Dog(Collar collar, int size) { theCollar = collar; dogSize = size; } public Collar getCollar() { return theCollar; } private void writeObject(ObjectOutputStream os) { // throws IOException { // 1 try { os.defaultWriteObject(); // 2 os.writeInt(theCollar.getCollarSize()); // shouldn't we get NullPointerException, since theCollar has not been initialized yet??? } catch (Exception e) { e.printStackTrace(); } } private void readObject(ObjectInputStream is) { // throws IOException, ClassNotFoundException { // 4 try { is.defaultReadObject(); // 5 theCollar = new Collar(is.readInt()); // 6 } catch (Exception e) { e.printStackTrace(); } } } public class SerializeDog { public static void main(String[] args) { Collar c = new Collar(3); Dog d = new Dog(c, 5); System.out.println("before: collar size is " + d.getCollar().getCollarSize()); try { FileOutputStream fs = new FileOutputStream("testSer.ser"); ObjectOutputStream os = new ObjectOutputStream(fs); os.writeObject(d); os.close(); } catch (Exception e) { e.printStackTrace(); } try { FileInputStream fis = new FileInputStream("testSer.ser"); ObjectInputStream ois = new ObjectInputStream(fis); d = (Dog) ois.readObject(); ois.close(); } catch (Exception e) { e.printStackTrace(); } System.out.println("after: collar size is " + d.getCollar().getCollarSize()); } }