Can Java's Array clone() return null?

Question

Given this code:

public class SoundAndFilterCollection {

    private final Sound[] sounds;
    private final Filter[] filters;

    public SoundAndFilterCollection(Sound[] sounds, Filter[] filters) {
        this.sounds = sounds.clone();
        this.filters = filters.clone();

        Arrays.sort(sounds);
        Arrays.sort(filters);
    }

    public Sound[] getSounds() {
        return sounds.clone();
    }

    public Filter[] getFilters() {
        return filters.clone();
    }
}

I'm having a NullPointerException when doing getSounds():

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object gab[].clone()' on a null object reference
at com.mycompany.messenger.push2talk.domain.SoundAndFilterCollection.getSounds(SoundAndFilterCollection.java:24)
at com.mycompany.messenger.shareinchat.chatbar.hiddenpanel.views.soundstickers.presenter.SoundStickersPanelPresenter.setSoundsViews(SoundStickersPanelPresenter.java:92)
at com.mycompany.messenger.shareinchat.chatbar.hiddenpanel.views.soundstickers.presenter.SoundStickersPanelPresenter.access$000(SoundStickersPanelPresenter.java:20)
at com.mycompany.messenger.shareinchat.chatbar.hiddenpanel.views.soundstickers.presenter.SoundStickersPanelPresenter.access$200(SoundStickersPanelPresenter.java:20)
at com.mycompany.messenger.shareinchat.chatbar.hiddenpanel.views.soundstickers.presenter.SoundStickersPanelPresenter$3.onDoneWithContext(SoundStickersPanelPresenter.java:59)
at com.mycompany.messenger.shareinchat.chatbar.hiddenpanel.views.soundstickers.presenter.SoundStickersPanelPresenter$3.onDoneWithContext(SoundStickersPanelPresenter.java:56)
at com.mycompany.deferred.Done$UIContextual.onDone(Done.java:35)

My question is: how can I have a null object in getSounds() with this implementation? I've tested Array clone() in JDK 1.8 and in a couple of Android devices and it's never returning null.

About the 2 Arrays.sort() I'm aware that they're sorting the wrong reference and I don't think they're relevant for this crash, but I wanted to share the code just like it is.

PS: Also, I'm having this crash in a huge variety of phones, so I don't think it is related with a strange implementation of clone() in a modified phone.

And just to clarify, `sounds` passed in via the constructor isn't `null`? — Michael Dodd, Feb 07 '17 at 10:59
Have a look at [Does calling clone() on an array also clone its contents](http://stackoverflow.com/questions/5821851/does-calling-clone-on-an-array-also-clone-its-contents) — Mick Mnemonic, Feb 07 '17 at 11:03
@MichaelDodd if it were null, we will have a NPE when building the object — Guillermo Merino, Feb 07 '17 at 11:07
@MickMnemonic but in that case I will have an empty array with wrongly cloned sounds, right? — Guillermo Merino, Feb 07 '17 at 11:08
Are they relevant for this? they're just POJOs implementing Comparable. But if you think I should add them to the question I will :) — Guillermo Merino, Feb 07 '17 at 11:32

score 0 · Answer 1 · edited May 23 '17 at 11:53

0

Mystery solved, this class was being instantiated with Gson in a cache, as I've seen here this is possible even without an empty constructor.

This class was obfuscated with proguard so it wasn't able to recover the serialized info and it was initialized with null values

edited May 23 '17 at 11:53

Community

1
1

answered Feb 07 '17 at 12:55

Guillermo Merino

3,197
2
17
34

Can Java's Array clone() return null?

1 Answers1