CS102 · Collections · Annotated SlidesJava Collection Framework
Original
Overview

Java Collection Framework

The Collections Framework (interfaces, implementations, algorithms), Collection vs. Map, Set vs. List, ArrayList and its methods, iterators, the diamond <>, Collections.sort and Collections.binarySearch.

How to read this page

Every original slide is shown unchanged. Yellow marks on a slide point to a numbered note: hover or tap a mark to jump to its note, and hover a note to see its marks. Questions tagged Past exam appeared on a real paper; Prediction questions are likely angles, not confirmed. Pick an answer to each question: a wrong pick tells you why it is wrong, so you can try again.

All 33 slides
  1. 1 Slide 1
  2. 2 Objective
  3. 3 Java Collections Framework
  4. 4 Collections Framework is a unified architecture for managing collections
  5. 5 Interfaces
  6. 6 Collections Framework Implementations
  7. 7 Collection
  8. 8 Map
  9. 9 Operations
  10. 10 Collections Methods
  11. 11 Slide 11
  12. 12 Slide 12
  13. 13 — A List (sometimes called a sequence ) is an
  14. 14 Array List
  15. 15 Array List
  16. 16 Introduction to Collections and Class ArrayList
  17. 17 Introduction to Collections and Class ArrayList (Cont.)
  18. 18 Slide 18
  19. 19 Introduction to Collections and Class ArrayList (Cont.)
  20. 20 Slide 20
  21. 21 Slide 21
  22. 22 Slide 22
  23. 23 Code Example: ArrayListCollection
  24. 24 and ArrayList Iterator
  25. 25 Collection Interface
  26. 26 Slide 26
  27. 27 and ArrayList Iterator
  28. 28 Method sort
  29. 29 Arrays static asList
  30. 30 Collection Method Sort
  31. 31 Slide 31
  32. 32 Binary Search
  33. 33 public class GFG { public static void main(String[] args) {
Slide 1 / 33

Slide 1

Slide 1: Slide 1
Slide 2 / 33

Objective

Slide 2: Objective
Slide 3 / 33

Java Collections Framework

Slide 3: Java Collections Framework
Slide 4 / 33

Collections Framework is a unified architecture for managing collections

Slide 4: Collections Framework is a unified architecture for managing collections

Notes

  1. Three parts: interfaces, implementations (classes), algorithms (static methods in Collections).

Slide 5 / 33

Interfaces

Slide 5: Interfaces

Notes

  1. Core interfaces: Collection, Set (no duplicates), List (ordered, duplicates allowed), Queue, Map (key → value).

Exam angle

PredictionQ1

Which collection type does NOT allow duplicate elements?

Slide 6 / 33

Collections Framework Implementations

Slide 6: Collections Framework Implementations
Slide 7 / 33

Collection

Slide 7: Collection
Slide 8 / 33

Map

Slide 8: Map

Notes

  1. Map is NOT a Collection: it stores key–value pairs.

Exam angle

PredictionQ1

Map extends the Collection interface.

Slide 9 / 33

Operations

Slide 9: Operations
Slide 10 / 33

Collections Methods

Slide 10: Collections Methods
Slide 11 / 33

Slide 11

Slide 11: Slide 11
Slide 12 / 33

Slide 12

Slide 12: Slide 12
Slide 13 / 33

— A List (sometimes called a sequence ) is an

Slide 13: — A List (sometimes called a sequence ) is an
Slide 14 / 33

Array List

Slide 14: Array List
Slide 15 / 33

Array List

Slide 15: Array List

Notes

  1. ArrayList: like an array but resizes automatically; holds objects only (Integer, not int).

Exam angle

PredictionQ1

An ArrayList<int> declaration:

Slide 16 / 33

Introduction to Collections and Class ArrayList

Slide 16: Introduction to Collections and Class ArrayList
Slide 17 / 33

Introduction to Collections and Class ArrayList (Cont.)

Slide 17: Introduction to Collections and Class ArrayList (Cont.)
Slide 18 / 33

Slide 18

Slide 18: Slide 18
Slide 19 / 33

Introduction to Collections and Class ArrayList (Cont.)

Slide 19: Introduction to Collections and Class ArrayList (Cont.)

Notes

  1. Methods: add, add(index, e), get, set, remove, size, contains, indexOf, clear, isEmpty.

Exam angle

PredictionQ1

Which returns the number of elements in an ArrayList list?

Slide 20 / 33

Slide 20

Slide 20: Slide 20
Slide 21 / 33

Slide 21

Slide 21: Slide 21
Slide 22 / 33

Slide 22

Slide 22: Slide 22
Slide 23 / 33

Code Example: ArrayListCollection

Slide 23: Code Example: ArrayListCollection
Slide 24 / 33

and ArrayList Iterator

Slide 24: and ArrayList Iterator

Notes

  1. Iterator: hasNext(), next(), remove(): the safe way to remove while iterating.

Exam angle

PredictionQ1

Removing elements from a list inside a for-each loop is safe.

Slide 25 / 33

Collection Interface

Slide 25: Collection Interface
Slide 26 / 33

Slide 26

Slide 26: Slide 26
Slide 27 / 33

and ArrayList Iterator

Slide 27: and ArrayList Iterator
Slide 28 / 33

Method sort

Slide 28: Method sort
Slide 29 / 33

Arrays static asList

Slide 29: Arrays static asList
Slide 30 / 33

Collection Method Sort

Slide 30: Collection Method Sort
Slide 31 / 33

Slide 31

Slide 31: Slide 31
Slide 32 / 33

Binary Search

Slide 32: Binary Search

Exam angle

PredictionQ1

Collections.binarySearch requires the list to be:

Slide 33 / 33

public class GFG { public static void main(String[] args) {

Slide 33: public class GFG { public static void main(String[] args) {