Copy arbitrary collections about guava HOT 8 CLOSED

Original comment posted by jared.l.levy on 2007-11-01 at 05:14 AM

What's the use case for that kind of copying? When writing application code, I'd
rather explicitly specify the class of the copy. To maintain the iteration ordering
of the original, you can use a class like a LinkedHashMap.

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Original comment posted by limpbizkit on 2007-11-01 at 04:51 PM

I'm thinking in particular of utility methods that return a copy of their input - this includes methods like
intersection(), transform(), and filter() for various collections types.

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Original comment posted by kevinb9n on 2007-11-02 at 02:15 AM

Quite simply, "a wish for a clone() that worked."

I agree that this would be good to support, for the same reasons that the (failed)
idea of clone() was created in the first place.

This would enable things like Sets.union() to do what people expect (I think).

btw, the other thing I'm aware of that you can't do generically to a collection is
get an unmodifiable view of it!

  public static <C extends Collection<?>> C unmodifiableView(C collection) { ... }

This seems closely related, in that to make it work, we'd have to have tedious
itemized support for all the JDK collections plus have some interface or something
that other collections would be required to implement if they want to participate.

Big Yuck for us, but possibly useful to users?

Labels: -Type-Defect, Type-Enhancement

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Original comment posted by [email protected] on 2009-09-15 at 06:17 AM

clone() on collections, like on the jdk collections, would be useful.

I just got the following exception from eclipselink-2.0 M7, this is the reference
implementation of JPA-2.0.

Target Invocation Exception: java.lang.CloneNotSupportedException:
com.google.common.collect.Lists$TwoPlusArrayList
        at
org.eclipse.persistence.internal.jpa.transaction.EntityTransactionImpl.commitInternal(EntityTransactionImpl.java:102)
        at
org.eclipse.persistence.internal.jpa.transaction.EntityTransactionImpl.commit(EntityTransactionImpl.java:63)
        at org.metawb.astro.db.PersonTest.linkPersonTag(PersonTest.java:191)

FYI, This came from Lists.asList
        em.getTransaction().begin();
        for(int i = 0; i < 3; i++) {
            ps.get(i).setTagtypeCollection(Lists.asList(
                    tts.get(0), tts.get(i+1), new Tagtype[0]));
        }
        em.getTransaction().commit();

but this works ok

        ps.get(i).setTagtypeCollection(Lists.newArrayList(
                tts.get(0), tts.get(i+1)));

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Original comment posted by kevinb9n on 2009-09-17 at 06:02 PM

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Labels: Milestone-Post1.0

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Original comment posted by [email protected] on 2010-07-30 at 03:53 AM

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Labels: -Milestone-Post1.0

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Original comment posted by [email protected] on 2010-07-30 at 03:56 AM

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Labels: -Priority-Medium

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Original comment posted by [email protected] on 2011-01-26 at 08:51 PM

This is out of the scope of the guava project.

Status: WontFix

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