need to confirm - ArrayList size()

javaalien

Guys, what is the max size for ArrayList size()?
I have arraylist with size up to 4 000 000, is there any problem with it...
my application's running so slow when my arraylist size up to 2 000 000.
Please confirm with me..
Thank you.

sicarie

I would imagine it is limited by your heap size, which, in turn, is constrained by your system - how much RAM you have, how much you have allocated to the JVM, etc... There are ways to increase your heap size from the normal setting (I forget what that is off the top of my head, but you can google it), but you might end up needing to add more RAM to the system.

JosAH

Quote:

Originally Posted by javaalien

Guys, what is the max size for ArrayList size()?
I have arraylist with size up to 4 000 000, is there any problem with it...
my application's running so slow when my arraylist size up to 2 000 000.
Please confirm with me..
Thank you.

The theoretical maximum number of elements in an ArrayList is 2^31-1 but
memory constraints lower that nuber significantly. First assure that you are
able to store 4 million elements by passing the flag -Xmx<value> to the JVM
to allow it do increate the size of the heap to <value> (1024m would be fine)

Note that the ArrayList class has a nice constructor:

Expand|Select|Wrap|Line Numbers

ArrayList(int initialCapacity)

Set the value of initialCapacity to 4,000,000. This sets up an (empty) ArrayList
that can potentially contain that many elements without the need to reallocate
room for all the elements.

kind regards,

Jos

javaalien

Quote:

Originally Posted by JosAH

The theoretical maximum number of elements in an ArrayList is 2^31-1 but
memory constraints lower that nuber significantly. First assure that you are
able to store 4 million elements by passing the flag -Xmx<value> to the JVM
to allow it do increate the size of the heap to <value> (1024m would be fine)

Note that the ArrayList class has a nice constructor:

Expand|Select|Wrap|Line Numbers

ArrayList(int initialCapacity)

Set the value of initialCapacity to 4,000,000. This sets up an (empty) ArrayList
that can potentially contain that many elements without the need to reallocate
room for all the elements.

kind regards,

Jos

How to do that please?
I have tried this - java -Xmx1024m, but comes out all the usage..
Do I have to do this first and then only run my application?