5 File and Life Game of Life is Homework 4

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1 5 File and Life Game of Life is Homework Files 1. The following program reads the file rhubarb.txt line by line and copies it, line by line, to the console. 1 / 2 File reading and writing 3 kees 5 / 6 import java. util. ; 7 import java. io. ; 8 9 public class FileIO { 10 File source; 11 File target ; 12 Scanner scanner; 13 PrintWriter printwriter ; String infilename = rhubarb. txt ; 16 String outfilename = blahblah. txt ; void copy() { 19 try { 20 String line ; source = new File( infilename ); 23 scanner = new Scanner( source ); 24 target = new File( outfilename ); 25 printwriter = new PrintWriter ( target ); while ( scanner. hasnext()) { 28 line = scanner. nextline(); 29 printwriter. println ( line ); 30 } 31 printwriter. close (); // If you forget this, file contents will not be saved 32 } catch(filenotfoundexception e) { 33 System.out. println ( Could not find or open file due to \n +e ); 34 } 35 } public static void main(string [] args ) { 38 new FileIO(). copy(); 39 } 40 } Download this file from the web. make a text file 1, with the name rhubarb.txt and place it in the same folder as the.java file. Compile and run. 2. Modify this program to have it put each line backwards. There are numerous ways to do this, but as a preparation for the Game of Life (next exercise), use the method call line.tochararray() which returns the contents of line as an array of characters (char[]). Then write the characters one by one, backwards. 1 Use a program of your choice, a text editor, Dr Java, etc. Make sure you save as plain text. 1

2 3. Now have the program leave out every character e when writing to the file. Note that a char value can be expressed in Java with single quotes, such as e, 0, *. Furthermore, the type char is similar to int and values can be compared with ==. 5.2 The Game of Life The Game of Life was devised by the British mathematician John Horton Conway in The game actually describes how an initial configuration evolves over time according to simple, precise rules. Despite the simple and precise rules, the evolution from the initial configurations is hard to predict and quite similar looking initial configurations may give rise to quite different developments. The universe of the Game of Life is a two-dimensional orthogonal grid of square cells, each of which is in one of two possible states, alive or dead. Every cell interacts with its maximally eight neighbours, the immediately adjacent cells in orthogonal and diagonal direction. Cells on the border have less than eight neighbours. At each step in time, the following transitions occur: 1. Any live cell with fewer than two live neighbors dies, as if by loneliness. 2. Any live cell with more than three live neighbors dies, as if by overcrowding. 3. Any live cell with two or three live neighbors lives, unchanged, to the next generation. 4. Any dead cell with exactly three live neighbors comes to life. An initial generation is read from file. A new generation is created by applying the above rules on every cell, using the current generation, as if the rules were applied simultaneously on all cells. Write a program, using the following classes Field The class field contains a two-dimensional array of Cells named cells. The method print prints the current generation on the console. See the provided methods below. 1 void drawline() { 2 String s = + ; 3 for (int i =1; i <cells[0]. length 1; i ++) { s+= ; } 4 s += + ; 5 System.out. println ( s); 6 } 7 8 public void print () { 9 drawline(); 10 for (int i = 1; i < cells. length 1; i ++) { 11 System.out. print ( ); 12 for (int j = 1; j < cells [i ]. length 1; j ++) { 13 System.out. print ( cells [i ][ j ]. draw() ); 14 System.out. print ( ); // extra space for a more rectangular like output 15 } 16 System.out. println ( ); 17 } 18 drawline(); 19 } 2

3 Note that we use a border of one cell thick around the game cells. This simplifies the neighbour counting. When you do something for all cells of the grid, think whether you have to do this including the border cells or not. Add a method int numneighbours(int i, int j) that calculates the number of living neighbours of the cell with coordinates i and j. Add a method that calculates the next generation. You may want to use a technique as used in the Cellulitis exercise, where the new generation is stored in a separate grid and then swapped with the old generation. Another possibility is to store in each cell the number of neighbours. When this number is up to date for all cells, the state of each cell can be changed according to the rules Cell The class Cell has a boolean instance variable alive that is true when the cell is alive and false when the cell is dead. The method boolean isalive() returns this value. The method String draw() a space if it is dead. returns the cell as a character to be printed, i.e., a * if the cell is alive and The method void setalive(boolean state) changes the alive/dead state of the cell GameOfLife This class contains a Field. This field is created and initialized by a method void readinitial(string filename) that reads the initial generation from a file with this name. This is a text file that starts with two integers representing the width and the height of the real playing field (without the border) and then for each row a line of characters * and. representing a live resp. a dead cell. Read each line as a String (by nextline and then use the method char[] tochararray() that returns the characters of the String it is applied to as an array. The method play() asks the filename of the file to read the initial generation from, the number of generations and a string for the inheritance part (which will be either age or stars ). If you choose to not do the optional part, you can simply skip the input string by writing scanner.nextline(); Inheritance This is an extra question for scoring a ten. It can be interesting to see how old a cell is. To this purpose, add a subclass AgedCell of Cell that behaves as a Cell and furthermore adds functionality for recording the age of the cell (the number of generations since the last time it became alive). Override the draw method of the Cell class so that it gives the age instead of a star. Also override other methods from the Cell class to add aging functionality. Use a single digit. When the age is above 9, use an X. The initial generation read is stored in an array of AgedCells instead of Cells. No changes are needed in the Field class and this should be enough to get the right display. Tip: Read on class inheritance and the super keyword. 3

4 5.3 Input, Output, and test files Testcase 1 For testcase 1 you need to use the file testzero.txt which can be obtained from the website. This testcase adresses a normal square Game Of Life grid. note the optional line stars we put here! > testzero.txt > 2 > stars * * * 4

5 5.3.2 Testcase 2 For testcase 2 you need to use the file testone.txt which can be obtained from the website. This testcase adresses a rectangular Game Of Life grid. note the optional line stars we put here! > testone.txt > 1 > stars * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 5

6 5.3.3 Testcase 3 For testcase 3 you need to use the file testtwo.txt which can be obtained from the website. This testcase adresses the extra functionality as specified in section > testtwo.txt > 3 > age May