| Interface |
Class/implementation |
Description |
| List |
ArrayList |
List |
| LinkedList |
List |
| Vector |
Vector |
| Stack |
Stack |
| Set |
HashSet |
Set |
| TreeSet |
Set |
| SortedSet |
Sorted set |
| Map |
HashMap |
Map/dictionary |
| TreeMap |
Map/dictionary |
| SortedMap |
Sorted dictionary |
| Hashtable |
Hash-table |
Declaration Syntax:
List<String> list = new ArrayList<String>();
Set<String> set = new HashSet<String>();
Map<String, String> map = new HashMap<String, String>();
ADD Elements Syntax:
list.add(“techBuddha”);
set.add(“techBuddha”);
map.put(“key”, “techBuddha”);
Traversing Collection Syntax:
Iterator<String> iterator = list.iterator();while (iterator.hasNext()) {
String text = iterator.next(); System.out.println(text);}
—————————————————-
Iterator<String> iterator = set.iterator();
while (iterator.hasNext()) { String text = iterator.next(); System.out.println(text);}
——————————————————
Iterator<Map.Entry<String, String>> iterator = map.entrySet().iterator();while (iterator.hasNext()){ Map.Entry<String, String> pair = iterator.next(); String key = pair.getKey(); String value = pair.getValue(); System.out.println(key + “:” + value);
}
—————————————————–
Traversing Collection with ShortHand Fast For Loop:
for (String text : list) { System.out.println(text); }
——————————————————-
for (String text : set) { System.out.println(text); }
——————————————————-
for (Map.Entry<String, String> pair : map.entrySet()){ String key = pair.getKey(); String value = pair.getValue(); System.out.println(key + “:” + value);}
——————————————————-
Methods for Set:
| Operation |
Method |
| Add element(s) |
add(), addAll() |
| Remove element(s) |
remove(), removeAll() |
| Check for the presence of element(s) |
contains(), containsAll() |
Methods for Map:
| Operation |
Method |
| Get a set of all pairs |
entrySet() |
| Get a set of all keys |
keySet() |
| Get a set of all values |
values() |
| Add a pair |
put(key, value) |
| Get the value for the specified key |
get(key) |
| Check whether the specified key is present |
containsKey(key) |
| Check whether the specified value is present |
containsValue(value) |
| Check whether the Map is empty |
isEmpty() |
| Clear the Map |
clear() |
| Remove the value for the specified key |
remove(key) |
Collection Methods:
ArrayList<Integer> list = new ArrayList<Integer>();
sort() : Collection.sort(list);
max() : Collection.max(list);
min() : Collection.min(list);
reverse() : Collection.reverse(list);
shuffle() : Collection.shuffle(list);
swap() : Collection.swap(list, i, j);
unmodifiableList() : creates immutable arrayList from an array.
List<String> weekEndDays = Collections.unmodifiableList(new ArrayList<>(Arrays.asList(saturday, sunday)));
disjoint() : It checks whether two collections intersect, returns false if intersection is non null otherwise true.
ArrayList<String> list1 = new ArrayList<>(Arrays.asList(sunday, monday, tuesday));ArrayList<String> list2 = new ArrayList<>(Arrays.asList(saturday, sunday));
Collection.disjoint(list1, list2); // will return false, sunday is common.
Collection Initialization:
public static Set join(Set a, Set b)
{
/*Double braces initialization*/
return new HashSet() {{ addAll(a); addAll(b); }}
}
buddhaTech 