java 6 NavigableMap related Query

[Harish Tam]

I have this program as follows

 
public static void main(String[] args) {
NavigableMap navMapSimple = new ConcurrentSkipListMap();

navMapSimple.put(1, "One");
navMapSimple.put(2, "Two");
navMapSimple.put(3, "Three");
navMapSimple.put(4, "Four");

System.out.println("navMapSimple firstEntry :"+navMapSimple.firstEntry());
System.out.println("navMapSimple firstEntry Key :"+navMapSimple.firstEntry().getKey());
System.out.println("navMapSimple firstEntry Value :"+navMapSimple.firstEntry().getValue());
System.out.println("navMapSimple pollFirstEntry Key :"+navMapSimple.pollFirstEntry().getKey());
System.out.println("navMapSimple pollFirstEntry Value :"+navMapSimple.pollFirstEntry().getValue());
System.out.println("navMapSimple pollFirstEntry :"+navMapSimple.pollFirstEntry());
System.out.println("navMapSimple lastEntry :"+navMapSimple.lastEntry());
System.out.println("navMapSimple Poll lastEntry :"+navMapSimple.pollLastEntry());
System.out.println("navMapSimple get()"+navMapSimple.get(2));	

the output of the above is something like this

navMapSimple firstEntry :1=One
navMapSimple firstEntry Key :1
navMapSimple firstEntry Value :One
navMapSimple pollFirstEntry Key :1
navMapSimple pollFirstEntry Value :Two
navMapSimple pollFirstEntry :3=Three
navMapSimple lastEntry :4=Four
navMapSimple Poll lastEntry :4=Four
navMapSimple get()null

My Question is related to the behavior of NavigableMap . cause
if you check the output then you will notice that even when i polled first entry of the map it gave me invalid value,but the key was totally correct.
Can anybody puts some knowledge on this and try to explain me as to why this behavior and gave me the second entry value when i polled first entry in this case. And there is a null return in case of a simple get.

Thanks

[Paul Clapham]

Harish Tam wrote:if you check the output then you will notice that even when i polled first entry of the map it gave me invalid value,but the key was totally correct.

I didn't see any invalid value. Could you clarify what you thought was invalid about the output you posted? It all looks perfectly reasonable to me.

(However I suspect you may not completely understand what the pollFirstEntry method does. I recommend you review the API documentation.)

[Harish Tam]

check this line of the output

navMapSimple pollFirstEntry Value :Two

I this this is not valid ,it is One and not Two

Right ?

[Paul Clapham]

No, I think the output you posted is correct. Can you explain why you expect what you said? After re-reading the API documentation for the method, that is? In particular the first word of the description of the method?

[Harish Tam]

do point out if i am wrong in any case

I think the output should be
"navMapSimple pollFirstEntry Value :One "
instead of
"navMapSimple pollFirstEntry Value :Two "

cause the firstEntry is with key : 1
and value :One

i am not sure but this is the case. as per me. If i am wrong please try this code with java 6 compiler

Thanks

[Paul Clapham]

What was the first word of the sentence I suggested you should read in the API documentation?

[Harish Tam]

i got this first part of the line "closest matches for given search targets" from the API docs is it cause of this

it returns the value as Two and not One

so in other case if there is a Question on this output in that case it can be either be One or Two

is there anything else to go with this or just the above part.

please clarify.

Thanks

[Paul Clapham]

You obviously haven't even read the description of the pollFirstEntry method, which is this:

The API documentation wrote:Removes and returns a key-value mapping associated with the least key in this map, or null if the map is empty.

[Harish Tam]

Thanks Paul

Looks like i should read the APIs carefully next time :-)

Thanks a bunch