COS 260 DAY 13 Tony Gauvin

Agenda Mini-quiz Five Graded Fixed Size Collections Ok results Questions Assignment 3 posted Due Oct 20 Assignment 4 posted Due 0ct 31 Mini-quiz Five Graded Ok results Fixed Size Collections

Capstone Project Capstone Project Description Fall 2017.pdf October 2 Proposal Due E-mailed to Tony in Blackboard October 27 Progress Report E-mailed to Tony in Blackboard November 16 Progress Report E-mailed to Tony in Blackboard November 30 Progress Report E-mailed to Tony in Blackboard December 12@8AM All Deliverables & Presentation Due Objects First with Java - A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling

Fixed-sized collections Objects First with Java Fixed-sized collections Introduction to arrays 6.0 © David J. Barnes and Michael Kölling

for loop with bigger step Objects First with Java for loop with bigger step // Print multiples of 3 that are below 40. for(int num = 3; num < 40; num = num + 3) { System.out.println(num); } © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved. © David J. Barnes and Michael Kölling

for loop and Iterator No post-body action required. for(Iterator<Track> it = tracks.iterator(); it.hasNext(); ) { Track track = it.next(); if(track.getArtist().equals(artist)) { it.remove(); } © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

Objects First with Java Review Arrays are appropriate where a fixed-size collection is required. Arrays use a special syntax. For loops are used when an index variable is required. For loops offer an alternative to while loops when the number of repetitions is known. Used with a regular step size. © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved. © David J. Barnes and Michael Kölling

The automaton project An array of ‘cells’. Each cell maintains a simple state. Usually a small numerical value. E.g., on/off or alive/dead. The states change according to simple rules. Changes affected by neighboring states. https://cs.stanford.edu/people/eroberts/courses/soco/projects/2004-05/automata-theory/basics.html © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

Cell states – blank cells are in state 0 A simple automaton nextState[i] = (state[i-1] + state[i] + state[i+1]) % 2; Odd-even Step Cell states – blank cells are in state 0 + 1 2 3 4 5 6 © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

Automation-V1 Exercise 7.24, 7.25, 7.26, 7.27 Objects First with Java - A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling

The conditional operator Choose between two values: condition ? value1 : value1 for(int cellValue : state) { System.out.print(cellValue == 1 ? ‘*' : ' '); } System.out.println(); Ex 7.28 , 7.29, 7.30 © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

Further advanced material

Arrays of more than one dimension Array syntax supports multiple dimensions. E.g., 2D array to represent a game board, or a grid of cells. Can be thought of as an array of arrays. © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

The brain project Cell[][] cells; ... cells = new Cell[numRows][numCols]; for(int row = 0; row < numRows; row++) { for(int col = 0; col < numCols; col++) { cells[row][col] = new Cell(); } © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

Alternative iteration for(int row = 0; row < cells.length; row++) { Cell[] nextRow = cells[row]; for(int col = 0; col < nextRow.length; col++) { nextRow[col] = new Cell(); } ‘Array of array’ style. Requires no access to numRows and numCols. Works with irregular shape arrays, which are supported in Java. © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

Brain Objects First with Java - A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling

Update Rules for Brain Rules to update a cell A cell that is alive changes its state to dying A cell that is dying changes its state to dead A cell that is dead changes to alive if exactly two of its neighbors are alive, otherwise it remains dead Alive = 0, Dead = 1, Dying = 2 Objects First with Java - A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling

The Game of Life- Ex 7.68 https://bitstorm.org/gameoflife/ New rules Count neighbors that are alive If dead and 3 neighbors are alive, then change to alive If alive and < 2 or > 3 neighbors are alive, then dead Objects First with Java - A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling

Arrays and Streams java.util.Arrays has several stream() methods that return a Stream based on an array. IntStream is a Stream of int values. Instream.range() creates a sequential IntStream. toArray returns an array from a Stream. © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.