Well as far as I know ArrayList won't just do this behind your back. I would assume there is something else your app is doing that isn't shown here. Are you sure you never change what is in mPeople that could cause a new instance of an object to be created?
On Sat, Nov 5, 2011 at 10:16 PM, Jay <[email protected]> wrote: > Thank you for the reply. Is there some other mechanism by which the > objects in my array might be replaced with objects with the same type > and contents but different identities (i.e. don't compare as equal > using the default implementation)? Because that seems to be what is > happening (intermittantly). > > Thanks, > Jay > > On Nov 6, 12:00 am, Dianne Hackborn <[email protected]> wrote: > > None of the methods you are using will copy an object. Generally you > must > > explicitly call clone() to do this. > > > > > > > > > > > > > > > > > > > > On Sat, Nov 5, 2011 at 6:25 AM, Jay <[email protected]> wrote: > > > I assume this is an Android question, though it may just betray my > > > ignorance of Java memory management. > > > > > I have an activity designed to randomly pick a person from a list, and > > > to not repeat anyone until everyone has been chosen. The core logic of > > > the pick method looks like this: > > > > > ArrayList<Person> peopleCopy = new ArrayList<Person>(mPeople); > > > peopleCopy.removeAll(mRecent); > > > Person person = peopleCopy.get(mRNG.nextInt(peopleCopy.size())); > > > mRecent.add(person); > > > // Display chosen person in UI > > > > > Both mPeople and mRecent are referenced by adapters that feed into > > > ListViews. > > > > > The bug I was finding is that the same person was being chosen more > > > than once in a cycle, despite the code above. I had a hell of a time > > > tracking it down; I couldn't duplicate it on the emulator or on the > > > actual device when connected to the debugger. I finally managed to > > > "catch" the bug in progrss on the device and plug it in to the > > > debugger. Based on the object id fields, it appears that the problem > > > is that the Person objects referenced my mRecent were different from > > > the ones in peopleCopy, which is why the removeAll method was not > > > subtracting them correctly. I implemented appropriate equals() and > > > hashcode() methods on Person and that seems to have fixed the problem. > > > > > My question is where/when/why were the Persons in mRecent and/or > > > mPeople being replaced with clones? It wasn't happening all the time; > > > based on observations with the debugger, it appears that usually the > > > lists referenced the same objects as I expected them to. Does the > > > framework sometimes clone objects referenced by adapters or does Java > > > or am I misreading this whole situation? > > > > > Thanks, > > > Jay > > > > > -- > > > You received this message because you are subscribed to the Google > > > Groups "Android Developers" group. > > > To post to this group, send email to > [email protected] > > > To unsubscribe from this group, send email to > > > [email protected] > > > For more options, visit this group at > > >http://groups.google.com/group/android-developers?hl=en > > > > -- > > Dianne Hackborn > > Android framework engineer > > [email protected] > > > > Note: please don't send private questions to me, as I don't have time to > > provide private support, and so won't reply to such e-mails. All such > > questions should be posted on public forums, where I and others can see > and > > answer them. > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/android-developers?hl=en > -- Dianne Hackborn Android framework engineer [email protected] Note: please don't send private questions to me, as I don't have time to provide private support, and so won't reply to such e-mails. All such questions should be posted on public forums, where I and others can see and answer them. -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
