garbage collection

[srinivas sridaragaddi]

   
class grab1 {
public void finalize() {System.out.print ("finalize");}
}
class Test {
private static void f(grab1[] array) {
array[0] = null;
array[1] = array[0];
array[2] = array[1];
array = null;
}
public static void main (String[] args) {
grab1[] array = new grab1[4];
for (int i=0; i<array.length; i++)
   array[i] = new grab1();//line1
f(array);
System.gc();
}
}  
 
as arrays are objects they also leave on heap . at line1 there are totally 8 objects 
created on heap
 
1) is this understanding correct.
2) the total no of objects eligible for garbage collection are 4 
 

please explain...  
 
 

[Srinivasan Mahadevan]

There are totally 5 objects created on the heap, NOT 8 objects. I think you have assumed that for new grab1[4], 4 objects have been created. Please note that it is just a single array object and not 4 objects. The 5 objects are as follows:
1 grab1 array object
4 grab1 objects

Out of these 5 objects, 3 grab1 objects (i.e. the first 3 created grab1 objects) are eligible for garbage collection. The last grab1 object and the grab1 array object will remain active and are not eligible for garbage collection. Please note that inside the method "f", you set array to null. This actually sets the copy of the reference to be set to null and the actual array reference in the main method remains unaffected and is not set to null.