"Java - Collections (Basics)"

How things are related in Collections?

Iterable ← Collection ← List ← Queue ← Set

List → ArayList, LinkedList, Vector ← Stack Set → HashSet, LinkedHashSet SortedSet → TreeSet

What are collections where can we use them in real life (Doing small stuff)

Collections are a represents a groups of same objects. python has list, c++ has vector …etc.

How to do processing on collections

How to traverse over collections ?

ArrayList<String> myCollection = new ArrayList<>();  
names.add("Bleh");  
names.add("Mary");  
names.add("Bleh");

• For Each

for (String x: myCollection) {
	System.out.println(x);
}

• Iterator()

for (Iterator<?> it = myCollection.iterator(); it.hasNext(); ){
	System.out.println(it.next());
}

Collection Interface Bulk Operations

Bulk operations perform an operation on an entire Collection. You could implement these shorthand operations using the basic operations, though in most cases such implementations would be less efficient. The following are the bulk operations:

• containsAll — returns true if the target Collection contains all of the elements in the specified Collection.
• addAll — adds all of the elements in the specified Collection to the target Collection.
• removeAll — removes from the target Collection all of its elements that are also contained in the specified Collection.
• retainAll — removes from the target Collection all its elements that are not also contained in the specified Collection. That is, it retains only those elements in the target Collection that are also contained in the specified Collection.
• clear — removes all elements from the Collection.