Re: Strange behavior of a java.util.Vector

From: Jan van Mansum (jvm_at_nospam.com)
Date: 01/25/04 

Date: Sun, 25 Jan 2004 23:11:33 +0100

Remember that in Java all objects and arrays are actually references
(like pointers). So you are adding the same "reference to an array"
(namely the array "outPutLine") three times. All three elements of the
Vector will point to the same array.

HTH, regards,
Jan van Mansum.

Konrad Den Ende wrote:

> I'm not sure if i'm going mad or stupid but as far as i can rely
> on my eyes, when i ADD an element to a Vector, it gets put on
> ALL the position, instead of the last one. It's like if it rolls all
> the way down the list leaving its footprints along the way.
>
> I wrote, like:
> import java.util.*;
>
> public class Temp {
> public static void main (String[] arg) {
> Vector vec = new Vector ();
> String[] outPutLine = new String[3];
> String line;
> for (int k = 0; k < 4; k++) {
> for (int i = 0; i < outPutLine.length; i++)
> outPutLine[i] = "S(" + i + ";" + k + ")";
> vec.add (outPutLine);
>
> System.out.println ("outPutLine " + k + " is: \t\t" + outPutLine[0] +
> "\t" + outPutLine[1] + "\t" + outPutLine[2]);
> System.out.println ("The result is:");
>
> String test = "";
> for (int i = 0; i < vec.size (); i++) {
> for (int j = 0; j < 3; j++)
> test += ((String[])vec.get (i))[j];
> test += "\n";
> }
> System.out.println (test + "\n---------------------------------\n");
> }
> }
> }
>
> So, is it just me or is there funky with the output? Where did the
> element S(0;0) go, for instance?!
>

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