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
