Re: Copying a List to a List of Lists

From:
"Alex" <alexander.webb@gmail.com>
Newsgroups:
comp.lang.java.help
Date:
14 Jul 2006 03:14:41 -0700
Message-ID:
<1152872081.422426.151990@s13g2000cwa.googlegroups.com>
Sorry there was an error in the code I posted: I actually do:

A.add(B);

Hendrik Maryns wrote:

Alex schreef:

Hi,

I am having trouble with the following: I wish to have a list of lists
of type Double called A. I then have a separate List of Doubles called
B which i wish to add to A. I then want to be able to clear B and reuse
it without clearing what I have added to A.

Currently my code looks like:

for(int i=0;i<seqLength;i++)
        {
            B.clear();

            for(int j=i+1;j<seqLength;j++)
            {
                if(fourGameteTest(i,j))
                {
                    B.add(segPositions.get(j));
                }
            }

            A.get(i).add(B);
            
A.get(i).addAll(B);
                 }

However, it seems that due to, I guess the element held in A being a
reference to the same place as B, when B is cleared A ends up having no
elements. How can I do this so as to be able to reuse B but not lose
what I have stored in A?


If you made this code generic, it would give a type error: You are
adding B to the ith list in A, instead you probably want to add all
values of B, see above.

H.
--
Hendrik Maryns

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