**NO PAPER ANSWERS. ALL ANSWER SUBMISSIONS SHOULD BE ABLE TO RUN WITH NO ERRORS**

**TO CREATE THIS JAVA PROGRAM USE ECLIPSE NEON**

The assignment is as follows:

Connect four is a two-player board game in which the players alternately drop colored disks into a seven-column, six-row vertically-suspended grid.

The objective of the game is to connect four same-colored disks in a row, a column, or a diagonal before your opponent can do likewise. The program prompts a player to drop a RED disk onto a column 0-6. Whenever a disk is dropped, the program redisplays the board on the console and determines the status of the game (win, draw, or continue). The computer player will RANDOMLY choose a column to drop a YELLOW disk onto. If a player tries to drop a disk on a column that is full, the turn is lost.

In other words, create a "1 player" version of the game,"Connect four." After the player is prompted to drop a disc (R). The computer will automatically drop the other disc (Y) in a random spot.

Sample output:

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

Drop a red disk at column (0-6): 0 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | R | | | | | | | 

Computer chose column 4 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | R | | | | Y | | | 

Drop a red disk at column (0-6): 0 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | R | | | | | | | 

 | R | | | | Y | | | 

Computer chose column 5 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | R | | | | | | | 

 | R | | | | Y | Y | | 

Drop a red disk at column (0-6): 0 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | R | | | | | | | 

 | R | | | | | | | 

 | R | | | | Y | Y | | 

Computer chose column 6 

 | | | | | | | | 

 | | | | | | | | 

 | | | | | | | | 

 | R | | | | | | | 

 | R | | | | | | | 

 | R | | | | Y | Y | Y | 

Drop a red disk at column (0-6): 0 

 | | | | | | | | 

 | | | | | | | | 

 | R | | | | | | | 

 | R | | | | | | | 

 | R | | | | | | | 

 | R | | | | Y | Y | Y | 

Red wins! Use this code to help: 

import java.util.Scanner;

/** * Chapter 8 Exercise 20: * * (Game: connect four) Connect four is a two-player board game * in which the players alternately drop colored disks into a seven-column, * six-row vertically suspended grid, as shown below. * The objective of the game is to connect four same-colored disks in a row, * a column, or a diagonal before your opponent can do likewise. The program * prompts two players to drop a red or yellow disk alternately. In the preceding * figure, the red disk is shown in a dark color and the yellow in a light color. * Whenever a disk is dropped, the program re-displays the board on the console * and determines the status of the game (win, draw, or continue). * */ public class Connect4 {

static boolean isPlayer1Turn = true; static boolean hasWon = false;

public static void main(String[] args) {

String[][] m = createGrid(6,7); Scanner input = new Scanner(System.in); int column;

while (!hasWon) {

String diskColor = (isPlayer1Turn) ? "red" : "yellow";

displayMatrix(m); boolean isFirstInput = true; do { if (!isFirstInput) { System.out.println("COLUMN IS FULL. Try again..."); } System.out.print("Drop a " + diskColor + " at column (06): "); column = input.nextInt(); isFirstInput = false; } while (!dropDisk(m, column));

if (isConsecutiveFour(m)) { displayMatrix(m); System.out.print("The "+diskColor+" player won! Do you want to play again? (y/n)"); char s = input.next().charAt(0); if (s == 'y' || s == 'Y') { m = createGrid(6, 7); isPlayer1Turn = false; } else { System.exit(0); } }

isPlayer1Turn = !isPlayer1Turn; }

}

public static void displayMatrix(String[][] m) {

for (int i = 0; i < m.length; i++) { for (int j = 0; j < m[i].length; j++) { System.out.print(m[i][j]); } System.out.println(""); }

}

public static String[][] createGrid(int row, int column) {

String[][] m = new String[row][column]; for (int i = 0; i < m.length; i++) {

for (int j = 0; j < m[i].length; j++) { if (j == 0) m[i][j] = "| |"; else m[i][j] = " |";

} } return m; }

public static boolean isConsecutiveFour(String[][] m) {

String s = (isPlayer1Turn) ? "R" : "Y";

int occurrence = 0; // (m[0].length - 3) --> reason: only checking occurrences of 4 for (int j = 0; j < m[0].length - 3; j++) { int y = m.length - 1; // row always starts on last row int x = j; while (x < m[0].length && y >= 0) {

if (m[y][x].contains(s)) { // | | | | | |R|R| occurrence++; // | | | | |R|R|R| if (occurrence == 4) return true; // | | | |R|R|R|R| } else { // | | |R|R|R|R| | occurrence = 0; // | |R|R|R|R| | | } // |R|R|R|R| | | | x++; y--; } }

// (m.length - 2) --> reason: only checking occurrences of 4 // and last row has already been checked for (int i = m.length - 2; i > 2; i--) { int x = 0; // column always starts on the left side int y = i; occurrence = 0; while (x < m[0].length && y >= 0) { // | | | |R|R| | | // | | |R|R| | | | // | |R|R| | | | | if (m[y][x].contains(s)) { // |R|R| | | | | | occurrence++; // |R| | | | | | | if (occurrence == 4) return true; // | | | | | | | | } else { occurrence = 0; }

x++; y--; } }

// j >= 3 --> reason: only checking occurrences of 4 for (int j = m[0].length - 1; j >= 3; j--) { int y = m.length -1; // row always starts on last row int x = j; occurrence = 0;

while (x >= 0 && y >= 0) { // |L|L| | | | | | if (m[y][x].contains(s)) { // |L|L|L| | | | | occurrence++; // |L|L|L|L| | | | if (occurrence == 4) return true; // | |L|L|L|L| | | } else { // | | |L|L|L|L| | occurrence = 0; // | | | |L|L|L|L| } x--; y--; }

}

// i > 2 --> reason: only checking occurrences of 4 for (int i = m.length - 2; i > 2; i--) { int x = m[0].length - 1; int y = i; occurrence = 0; while (x >= 0 && y >= 0) { // | | |L|L| | | | // | | | |L|L| | | if (m[y][x].contains(s)) { // | | | | |L|L| | occurrence++; // | | | | | |L|L| if (occurrence == 4) return true; // | | | | | | |L| } else { // | | | | | | | | occurrence = 0; } x--; y--; }

}

return false; }

public static boolean dropDisk(String[][] m, int column) {

// figure out which disk to drop String s; if (isPlayer1Turn) { s = (column > 0) ? "R|" : "|R|"; } else { s = (column > 0) ? "Y|" : "|Y|"; } boolean didRowUpdate = false; int row = 0;

// check if there is a disk in column // if there is get the proper row index for (int i = 0; i < m.length; i++) {

if (isClear(m[i][column])) { didRowUpdate = true; row = i; } }

if (!didRowUpdate) return false;

m[row][column] = s;

return true; }

public static boolean isClear(String s) {

return s.contains("| |") || s.contains(" |"); }

}