[x3d-public] Better approachs, was: Re: Java SOCKS! jsail/Navigation/OrthoViewpoint.java in X3DJSAIL

[John Carlson]

Corrections, learn something new daily!

If you google “immutable arrays in Java” the ai overview is good.  Make a
copy when returning, make final variables private.  That’s the easy
solution.

Also, the AI says:

import java.util.Arrays;
import java.util.Collections;
import java.util.List;

/* [ editor’s note ] I doubt this is feasible, unless we hide stuff in a
private constructor and call the private constructor with this(…) at the
beginning ordinary constructors.  Maybe worth a try, but likely the
stylesheet would be rough.  It’s probably easier to return a copy. But
perhaps you could do the below when initializing a final List? Worth a
try?  I’m not familiar with most of the stylesheet   I’m not sure if List
can be passed to equals()???*/

public class MyClass {
private final List<Integer> immutableList;

public MyClass(int[] initialArray) {
this.immutableList =
Collections.unmodifiableList(Arrays.asList(Arrays.stream(initialArray).boxed().toArray(Integer[]::new)));
}

public List<Integer> getImmutableList() {
return immutableList;
}
}

Reference to documentation:
https://docs.oracle.com/javase/8/docs/api/java/util/Collections.html#unmodifiableList-java.util.List-

There are other unmodifiable collections.

I’ll probably mess with my OArray.java to try this out, interesting!

On Tue, Jul 29, 2025 at 11:55 PM John Carlson <yottzumm at gmail.com> wrote:

> Apparently, the  FIELDOFVIEW_DEFAULT_VALUE should be final (immutable).  I
> think the story is, you can modify elements of an ArrayList<Float>, but you
> can't modify the variable.
>
> The magenta?  Looks wrong.  A final variable got overwritten.
> ##########################################
> ((((getFieldOfView().length > 0) &&
> !getFieldOfViewList().equals(FIELDOFVIEW_DEFAULT_VALUE)) ||
> !ConfigurationProperties.getStripDefaultAttributes()) /* ArrayList .x3d
> compare */ && !hasUSE())=false
> getFieldOfView().length > 0=true
> !getFieldOfViewList().equals(FIELDOFVIEW_DEFAULT_VALUE)=false
> !ConfigurationProperties.getStripDefaultAttributes()=false
> !hasUSE()=true
> getFieldOfViewList()=[0.0, 0.0, 20.0, 20.0]
> FIELDOFVIEW_DEFAULT_VALUE=[0.0, 0.0, 20.0, 20.0]
> ##########################################
>
> Later, the magenta is correct.  Why?
>
> ##########################################
> ((((getFieldOfView().length > 0) &&
> !getFieldOfViewList().equals(FIELDOFVIEW_DEFAULT_VALUE)) ||
> !ConfigurationProperties.getStripDefaultAttributes()) /* ArrayList .x3d
> compare */ && !hasUSE())=false
> getFieldOfView().length > 0=true
> !getFieldOfViewList().equals(FIELDOFVIEW_DEFAULT_VALUE)=false
> !ConfigurationProperties.getStripDefaultAttributes()=false
> !hasUSE()=true
> getFieldOfViewList()=[-1.0, -1.0, 1.0, 1.0]
> FIELDOFVIEW_DEFAULT_VALUE=[-1.0, -1.0, 1.0, 1.0]
> ##########################################
>
> Here's the definition of the variable:
>
> /** MFFloat field named <i>fieldOfView</i> has default value
> <i>{-1f,-1f,1f,1f}</i> (Java syntax) or <i>-1 -1 1 1</i> (XML syntax). */
> public static final ArrayList<Float> FIELDOFVIEW_DEFAULT_VALUE = new
> ArrayList<>(Arrays.asList(-1f,-1f,1f,1f));
>
> See example code to test (it gets even worse, even arrays themselves are
> mutable.
>
> import java.util.ArrayList;
> import java.util.Arrays;
>
> public class OArray {
>         public static final ArrayList<Float> FIELDOFVIEW_DEFAULT_VALUE =
> new ArrayList<>(Arrays.asList(-1f,-1f,1f,1f));
>         public static final float[] ARRAY_FIELDOFVIEW_DEFAULT_VALUE = new
> float [] {-1f,-1f,1f,1f};
>         public static void main(String[] args) {
>                 System.out.println(FIELDOFVIEW_DEFAULT_VALUE);
>                 FIELDOFVIEW_DEFAULT_VALUE.set(0, 0f);
>                 FIELDOFVIEW_DEFAULT_VALUE.set(1, 0f);
>                 FIELDOFVIEW_DEFAULT_VALUE.set(2, 20f);
>                 FIELDOFVIEW_DEFAULT_VALUE.set(3, 20f);
>                 System.out.println(FIELDOFVIEW_DEFAULT_VALUE);
>                 System.out.print(
>                                 ARRAY_FIELDOFVIEW_DEFAULT_VALUE[0]+" "+
>                                 ARRAY_FIELDOFVIEW_DEFAULT_VALUE[1]+" "+
>                                 ARRAY_FIELDOFVIEW_DEFAULT_VALUE[2]+" "+
>                                 ARRAY_FIELDOFVIEW_DEFAULT_VALUE[3]);
>                 System.out.println("");
>                 ARRAY_FIELDOFVIEW_DEFAULT_VALUE[0] = 0f;
>                 ARRAY_FIELDOFVIEW_DEFAULT_VALUE[1] = 0f;
>                 ARRAY_FIELDOFVIEW_DEFAULT_VALUE[2] = 20f;
>                 ARRAY_FIELDOFVIEW_DEFAULT_VALUE[3] = 20f;
>                 System.out.print(
>                                 ARRAY_FIELDOFVIEW_DEFAULT_VALUE[0]+" "+
>                                 ARRAY_FIELDOFVIEW_DEFAULT_VALUE[1]+" "+
>                                 ARRAY_FIELDOFVIEW_DEFAULT_VALUE[2]+" "+
>                                 ARRAY_FIELDOFVIEW_DEFAULT_VALUE[3]);
>                 System.out.println("");
>         }
> }
> $ java net/coderextreme/OArray
> [-1.0, -1.0, 1.0, 1.0]
> [0.0, 0.0, 20.0, 20.0]
> -1.0 -1.0 1.0 1.0
> 0.0 0.0 20.0 20.0
>
> So, yeah, Java socks!  The only thing that isn't final/mutable is
> variables.
>
> Don't you love the C foundation Java is based on?
>
> Anyone for Haskell?
>
> John
>
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