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Garbage collection (program)

 
Nabila Mohammad
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Hi.
This is the code
I got from a book explaining Garbage Collection.Cannot understand any part of the progam.Would be grateful if someone explain the stepwise execution of the program.
Also I did not understand

HeavyItem list=createList("X");
list = createList("Y");

itemA=new HeavyItem(itemID,null);

and the code written in the main method.

What exactly do you mean by these lines.

 
marc weber
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Originally posted by Nabila Mohammad:
...Also I did not understand

HeavyItem list = createList("X");
list = createList("Y");
itemA = new HeavyItem(itemID, null);...

It would be difficult to grasp garbage collection without understanding object creation, because garbage collection is all about "unreachable" objects that can be cleared from memory.

new HeavyItem(itemID, null) creates a new instance of HeavyItem by calling a HeavyItem constructor that takes arguments of a String and a HeavyItem. In this case, the String is referenced by itemID, and the HeavyItem is a null reference.

createList is a method that takes a String argument and returns a reference to a HeavyItem. In fact, the method creates three new instances of HeavyItem and returns a reference to one of these. But this HeavyItem HAS-A HeavyItem, which in turn HAS-Another HeavyItem.
 
Nabila Mohammad
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Hey.
Can you tell me where I can get the details of Object creation
besides the regular stuff.
ie.
MyClass obj=new MyClass();
 
marc weber
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What book are you using to learn Java?
 
Nabila Mohammad
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I m using A Programmer's guide to Java Certification by Khalid A.Mughal and Rolf W.Rasmussen.
I was referred for this book by one of my teachers.
 
ahmed yehia
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Hi Nabila
If you are preparing for Java Certification, then this book is for you, although others are recommended for SCJP, see JavaRanch FAQ.

However a Certification guide is not intended for teaching language basics instead teaches exam stuff.. If you aren't interested in SCJP then better find an introdutory book which focuses on learning the language.
 
Nabila Mohammad
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Can you suggest some link where i can brush my basics?
 
ahmed yehia
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Sun Java Tutorial
 
Nabila Mohammad
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Thanks.
 
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