Re: Collection
Garg <sendtogarg@gmail.com> writes:
in ArrayList, Vector we can get the value by providing posting number
Like:
String str = (String) arrList.get(4);
but arrayList can only store one object.
HashMap, TreeMap can store two maps (key and Object).
Can i get the value of the key and Object stored at the 4th place.
What fourth place? A HashMap has no inherent order, so you can't even
talk about places.
A LinkedHashMap guarantees the order of iteration to be preserved by
additions. In that case you can talk about the fourth element.
You'd get that by:
Iterator iter = myLinkedMap.entrySet().iterator();
iter.next();
iter.next();
iter.next();
Map.Entry fourth = iter.next();
However, if you want a list of pairs, don't misuse a map for it.
Make a list of pairs!
public class Pair<S,T> {
private final S fst;
private final T snd;
public Pair(S fst, T snd) {
this.fst = fst;
this.snd = snd;
}
public S getFirst() {
return fst;
}
public T getSecond() {
return snd;
}
}
private List<Pair<String,String>> list = new ArrayList<Pair<String,String>>;
// ...
Pair<String,String> fourth = list.get(4);
/L
--
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