Guided Notes
Collections
List, ArrayList, and LinkedList; Set and HashSet; Map and HashMap; sorting; iterators; and wrapper classes.
The Collections Framework
Slide 1 / 5java.util provides ready-made data structures that grow and shrink automatically:
• List — an ordered sequence that allows duplicates (ArrayList, LinkedList). • Set — unique values only (HashSet, TreeSet, LinkedHashSet). • Map — key–value pairs with unique keys (HashMap, TreeMap, LinkedHashMap).
Declare variables by the interface and create by the class: List<String> names = new ArrayList<>();
The <String> is a generic type: the list only holds Strings.
