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Local variable and Garbage Collection

 
Greenhorn
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Can anyone explain me the following sentence? I can't follow the explanation to the answer:
When the following method reaches line 8, how many of the String objects created in line 5 are eligible for garbage collection? Assume that the System.out object is not keeping a reference.
1.public void countDown()
2.{
3. for( int i = 10 ; i >= 0 ; i-- )
4.{
5.String tmp = Integer.toString( i );
6.System.out.println( tmp );
7. }
8.System.out.println("BOOM!");
9.}
ANSWER:
10
EXPLANATION:
Because only the last String object of the 11 created still has a reference. Because even though the tmp variable is out of scope in line 8, the local variable still has a reference.
 
Ranch Hand
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That doesn't make sense. If "tmp" is out of scope, then it no longer exists and therefore no longer holds a reference.
 
Ranch Hand
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I agree with Ron. All 11 objects are eligible for garbage collection when both the reference and the String objects go out of scope once control passes out of the loop.
 
Greenhorn
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Daniela Meyer,
There will be eleven String objects eligible for garbage collection after the method finishes execution.
I put some lines as shown below and ran the code ublic class Test
{
public static void main(String [] args)
{
Test obj = new Test();
obj.countDown();
}

public void countDown()
{
for( int i = 10 ; i >= 0 ; i-- )
{
String tmp = Integer.toString( i );
System.out.println( tmp );
}
System.out.println("BOOM!");
}
}
And I had the ff. result:
C:\java>java Test
10
9
8
7
6
5
4
3
2
1
0
BOOM!
Hence, if you check it, the for loop executed eleven times creating eleven objects on the whole.
Ikechukwu Morah.
 
Daniela Meyer
Greenhorn
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Thanks a lot to all of you!
11 was my answer, too, but the commercial MOC did tell me the answer described above.
 
Ron Newman
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What's a "commercial MOC" and what is its URL?
 
Daniela Meyer
Greenhorn
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Ron
A mock exam you pay for...
 
Ranch Hand
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Though the last variable is out of scope at line 8, in some JVM it could not have cleared it by line 8, but it would wait untill the end of the method. Others however may have done it. That is why the exam is not going to test the eligibility of a variable for garbage collection in that context. I think Kathy Sierra has already posted something similar.
Joshua Bloch wrote on page 19 in Effective Java:


It should be noted that on present day JVM (JDK1.3) implementations, it is not sufficient merely to exit the block in which a variable is defined; one must exit the containing method in order for a reference to vanish.

 
Cowgirl and Author
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Yeah, what Jose said
 
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