CODEWITHSUNDEEP
javagarbage-collection
someone
someone

Reputation: 6572

Is it a good practice to set an object to null after processing?

I have scenario like this:

public void processData(String name,String value) {

/* line 1 */    MyDTO dto = new MyDTO();  
/* line 2 */    dto.setName(name);
/* line 3 */    dto.setValue(value);
/* line 4 */    sendThroughJMSChannel(dto);
/* line 5 */    dto = null; //As a best practice, should I do this ?

}

In my program after line 4 I don't require dto for further processing. As a best practice, should I set dto to null as in line 5 or ignore it?

By setting it to null, I'm expecting fast garbage collection. Is it correct?

Upvotes: 15

Views: 12553

Answers (3)

Zeena
Zeena

Reputation: 429

As already been said, compiler is smart enough for the local scope but again in the non local scope it is a lot more context specific. One needs to understand how legitimate it is to nullify the reference at a particular point. Say when using a HashMap - 

Map<String, Object> entry = new HashMap<String, Object>();
String name = "test";             
Object o = new Object();          
entry.put(name, o);                

o = null; 
name = null; 

System.gc(); // Nothing is eligible !!! Still referenced by the Map.

Object test = entry.get("test");    // Returns the object.

The entry must be removed from being referenced from the HashMap first, in this scenario.

Upvotes: 0

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726509

No, do not set local variables to null to hasten their collection by the GC: the compiler is smart enough to figure it out without your help; the null assignments will only make your code look dirty.

Non-locals are a different story: if you have a member variable that might stay around for longer than necessary, it is a good idea to set it to null and prevent lingerer memory leaks.

Upvotes: 31

Jigar Joshi
Jigar Joshi

Reputation: 240880

It will be out of scope it self after line 4 (once method invocation is over) so not required in this case

Upvotes: 13

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