ArrayList Question

[k4ghg]

I was wondering if someone might help me get a grasp on arrayLists. I've read the books but an still having some problems.

I created a GUI to accept varing records. There are buttons to travers the records and each time I select a button I'm updating the arrayLists. ArrayList.add(Number, object); When I do forward the Number is incremented and when I go back its reduced.

By using the "Number" are are substituing a record or adding a new record and sliding the old one up? The program seems to bomb when I go back and forth between records.

Thanks

 

[timw]

When you specify an index for the add method, you are in fact inserting the object at that position in the list. The subsequent entries will all be indexed one greater.

This is mentioned in the JDK API Docs.

Tim
---------------------------
"Your morbid fear of losing,
destroys the lives you're using." - Ozzy

 

[sedj]

ArrayList.add() just adds a record to the list - when you access records, you use the get(int record) method.

Perhaps you could show a quick example to highlight your problem ?

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[Diancecht]

You can see an example here:

http://www.idevelopment.info/data/Programming/java/PROGRAMMING_Java_Programming.shtml

Cheers,
Dian

 

[k4ghg]

Thanks...I was suprised that it inserts the value and not replace. If anyone is interested I created two routines. If the item is new its added else I set it in place:

for (int n = 0; n > 10; n++){
if (aID.size ==0){
aID.add(n, ID[n]);
}
else(
aID.set(n, ID[n]);
}
}

Thanks again...Ronnie

 

[Diancecht]

Maybe you should take a look at HashMap, it stores key-value pairs that you could use to store your buttons.

Cheers,
Dian