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Garbage Collection

 
Henry Zhi Lin
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I got the following from exam lab,



How many object can be garbage collected here?

My answer is 0, but the correct answer is 1.

I am so confused here and find there is no alternative way to solve problem like this. Can anyone tip me how to solve such gc problem?

Thanks.
 
Henry Wong
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Let's name the object OA, OB, OC, OD, etc., as they are being created. This is to distinguish them from the reference that points to it. Furthermore, we will follow the instance variable that is part of these objects, to draw all the connections.

---------------------
After...

A a1=null;
A a2=new A(new A(null));
A a3=new A(a2);

You will get...



---------------------
After ...

a1=a3;

You will get...



---------------------
After ...

a1.a=new A(null);

You will get...



----------------------
After ...
a2.a=null;

You will get ...


And as you can see, the B object is now unreachable.

Henry
 
Henry Zhi Lin
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Thanks Henry,

You method are really cool. It is very clear what really happens.
 
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