Copying ArrayList

[ruds]

hi,
I have 2 arraylists al1 and al2. I'm copying al1 to al2 i.e.
al2=al1;
if i'm removing some elements from al2, the same elements from al1 too
are removed.
why so?
How do i prevent it?
How to copy array list can i clone it?

 

[Abhishek Srivastava]

hi,
I have 2 arraylists al1 and al2. I'm copying al1 to al2 i.e.
al2=al1;
if i'm removing some elements from al2, the same elements from al1 too
are removed.
why so?
How do i prevent it?
How to copy array list can i clone it?

http://java.sun.com/developer/JDCTechTips/2001/tt0410.html

- Abhi

 

[ruds]

Thanks a lot..

 

[Roedy Green]

hi,
I have 2 arraylists al1 and al2. I'm copying al1 to al2 i.e.
al2=al1;
if i'm removing some elements from al2, the same elements from al1 too
are removed.
why so?
How do i prevent it?
How to copy array list can i clone it?

all copying with

arraylist2 = arraylist1

does in give you two pointers to the same ArrayList.

You need to clone the ArrayList.

See if clone is defined.

See if there is a constructor that takes another ArrayList or List.

In a pinch, export an array and use that to create a new ArrayList.

see http://mindprod.com/jgloss/arraylist.html