should i close statement having local reference ?????

[dmjpro]

look at this code carefullyyyy .....

void test(Connection l_con)
{
Statement l_stmt = l_con.createStatement();
l_stmt.close(); //Sholud i do this to avoid maximum cursors open error
}

i mean when the method calling finished then the local reference l_stmt will be destroyed then will JVM close all resources associated with it ....

plz explain me in details ....

thanx

[r035198x]

look at this code carefullyyyy .....



i mean when the method calling finished then the local reference l_stmt will be destroyed then will JVM close all resources associated with it ....

plz explain me in details ....

thanx

Yes you should close it yourself. The JVM may close it before garbage collecting but that depends on the platform.

[dmjpro]

oh really .... is this true .....

could u say me one more thing does the JVM provided by SUN has this facility ...

plz say ....

thanxxxxx

[r035198x]

oh really .... is this true .....

could u say me one more thing does the JVM provided by SUN has this facility ...

plz say ....

thanxxxxx

Garbage collection like Concurrency is one of those things in Java that are not platform independant. You cannot say when a useless variable's contents are removed from memory. Even is you call System.gc(), garbage collection may not occur. It depends on the memory algorithms of the OS you are using. So leaving a connection open and hoping it will get closed on cleanup is not safe because you never know when clean up actually takes place.

[dmjpro]

thanx for ur detail info ... thanxxxxx

[dmjpro]

oh sorry i forget to mention ....

i don't understand the secind line ...

plz explain me in details ...........

[r035198x]

oh sorry i forget to mention ....

i don't understand the secind line ...

plz explain me in details ...........

which line, dj?

[dmjpro]

sorry i misspell ......

the second line....

plz say .... thanx

[r035198x]

sorry i misspell ......

the second line....

plz say .... thanx

Assuming you mean this:"You cannot say when a useless variable's contents are removed from memory."

A variable holds the address of where an object is stored in memory.

If you have

 
Double x = new Double(3); //memory for Double(3) object
Double y = new Double(5); //memory for Double(5) object
 

Then after

 x = y; 

The variable x is no longer refering to the object Double(3), but is now refering to the Double(5) object. The Double(3) object is no longer being referenced and there is no longer any way of accessing it now. We say that it is ligible for garbage collection. However, you cannot say whether it has been removed from memory yet. It is the duty of the garbage collector to remove that Double(3) object from memory and we don't know when exaclt the GC is going to remove that object from memory even though it is now useless.

[dmjpro]

ok now i can understand ur words ....

many many thanxxxx

[N002199B]

Assuming you mean this:"You cannot say when a useless variable's contents are removed from memory."

A variable holds the address of where an object is stored in memory.

If you have

 
Double x = new Double(3); //memory for Double(3) object
Double y = new Double(5); //memory for Double(5) object
 

Then after

 x = y; 

The variable x is no longer refering to the object Double(3), but is now refering to the Double(5) object. The Double(3) object is no longer being referenced and there is no longer any way of accessing it now. We say that it is ligible for garbage collection. However, you cannot say whether it has been removed from memory yet. It is the duty of the garbage collector to remove that Double(3) object from memory and we don't know when exaclt the GC is going to remove that object from memory even though it is now useless.

I hear you r0.
But Remember there are also primitive values to take care of. The Statement "A variable holds the address of where an object is stored in memory" May not necessarily hold coz primitives are not objects .... a java trade off from object orientation, for practicality........ A primitive variable actually holds the bit pattern of the value it represents.
My question is :Does that mean primitives are never garbage collected

[dmjpro]

yes why not .... i think u didn't get ros' point of view ........

he answered my question perspective ..... the primitive datas are garbage collected

[r035198x]

yes why not .... i think u didn't get ros' point of view ........

he answered my question perspective ..... the primitive datas are garbage collected

Anything that has memory reserved for it can be garbage collected. So I should have included the primitive types there. Of course the primitives are stored in a different manner than objects are. Primitives are stored in constant size memory. I should probably have also included the special way that Strings are handled but I thought that might have clouded the issue at hand.

[N002199B]

Anything that has memory reserved for it can be garbage collected. So I should have included the primitive types there. Of course the primitives are stored in a different manner than objects are. Primitives are stored in constant size memory. I should probably have also included the special way that Strings are handled but I thought that might have clouded the issue at hand.

I am new to this forumn, but so far I am impressed. Thanks. It's nice to be around "Real" java developers...I didn't mean to cloud the thread. Just an open mind taht scrutinises.

I hear u on the String object storage and immutability. I will let you post it on one of those tutorial postings that you so much keep updated.

Keep it up. I'm impressed

[dmjpro]

actually here the point u can understand clearly that how garbage collection depends on the meory issue of the OS .....

thanx N002199B u made me more clear ........

thanxxxxxx aallottt of thanxxxx