Retrieving items from Collection

I have a Collection c, which contains 3 items. I want to assign these 3 items to 3 different variables

Collection<Object> c;
var1 = firstItem;
var2 = secondItem;
var3 = thirdItem;


How can I extract the elements of the collection?

There is no effort from OP.
– pvpkiran
Jun 29 at 9:05

2 Answers
2

You can do it as following:

Collection<Object> collection = ...;
Iterator iterator = collection.iterator();
Object firstItem = iterator.next();
Object secondItem = iterator.next();
Object thirdItem = iterator.next();


Update:
This option is fine only if you are sure that collection contains at least 3 items. Otherwise, you need to check whether iterator has next item (method hasNext) before calling next.

hasNext

next

Don't forget to check for the existence of a next element, using iterator.hasNext(); as it may throw a NoSuchElementException.
– chŝdk
Jun 29 at 9:11

iterator.hasNext();

NoSuchElementException

chŝdk, you are right. I have updated my answer. Thanks.
– Timur Levadny
Jun 29 at 9:19

When I do it like this: iterator.next() there is an error When I do it like this: collection.iterator().next() there isn't Can I use the second one?
– ilinq
Jun 29 at 9:34

What is the error? The second option will always provide first item.
– Timur Levadny
Jun 29 at 9:40

Found: 'java.lang.Object' , required 'android.os.Parcelable'
– ilinq
Jun 29 at 9:52

Maybe this can help you :

Object array = c.toArray();
Object var1 = array[0];
Object var2 = array[1];
Object var3 = array[2];


Note toArray() return an array of Object so in case of another Type you have to cast the result for example or you can use :

toArray()

Collection<String> c = Arrays.asList("a", "b", "c");
String array = c.toArray(new String[c.size()]);
String var1 = array[0];
String var2 = array[1];
String var3 = array[2];


Or with a List

Collection<String> c = Arrays.asList("a", "b", "c");
List<String> list = (List<String>) c;
String var1 = list.get(0);
String var2 = list.get(1);
String var3 = list.get(2);


I think that Invoking toArray() for each item is not a good idea from performance perspectives.
– Timur Levadny
Jun 29 at 9:11

toArray()

Thank you @TimurLevadny this is correct I just fix it
– YCF_L
Jun 29 at 9:16

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