What is the JAVA connect four game?
I was wondering if you guys could point out any mistakes I've made in this program, and how to improve the code. It's a simple console-based Connect Four game. You use 0-5 to place your piece in the column you want. The goal of the game is to get four in a row, either vertically, horizontally or diagonally.
//imports
import java.util.Scanner;
public class Main{
//global variables
final static int WIDTH = 6;
final static int HEIGHT = 6;
final static int BOTTOM_ROW = WIDTH - 1;
//game board
static char[][] board = new char[WIDTH][HEIGHT];
//creates scanner
static Scanner scanner = new Scanner(System.in);
public static void main(String[] args){
//creates board
CreateBoard();
//tells player how to play
System.out.println("Use 0-5 to choose what column you want");
//displays board
PrintBoard();
//creates boolean to determine status of game
boolean flag = true;
//main game loop
while(flag){
//activates player 1s turn, then prints board
DropX();
PrintBoard();
//determines if player 1 has won
if(!CheckX()){
flag = false; //sets flag to false so loop is not repeated if player 1 won
break; //break to skip player 2s turn if won
}
//activates player 2s turn, then prints board
DropO();
PrintBoard();
//determines if player 1 has won
if(!CheckO()){
flag = false; //sets flag to false so loop is not repeated if player 2 won
break; // break for consistency
}
}
}
public static void CreateBoard() {
//fills board with '.' for the width and height
for (int w = 0; WIDTH > w; w += 1) {
for (int h = 0; HEIGHT > h; h += 1) {
board[w][h] = '.';
}
}
}
public static void PrintBoard() {
//prints the board
for (int w = 0; WIDTH > w; w += 1) {
for (int h = 0; HEIGHT > h; h += 1) {
System.out.print(board[w][h]);
}
System.out.println();
}
System.out.println();
}
public static void DropX(){
//creates a counter
int counter = 1;
//shows whos turn
System.out.println("Player 1 turn");
//gets input
int column = scanner.nextInt();
while(true){
if(column > WIDTH){
System.out.println("That's not a valid column");
break;
}
if (board[BOTTOM_ROW][column] == '.') { //checks to see if space is blank, puts X there if it is
board[BOTTOM_ROW][column] = 'X';
break; //breaks loop after placing
}else if(board[BOTTOM_ROW][column] == 'X' || board[BOTTOM_ROW][column] == 'O'){ //if space isn't blank, checks to see if one above is
if(board[BOTTOM_ROW - counter][column] == '.'){ //puts X if blank
board[BOTTOM_ROW - counter][column] = 'X';
break; //breaks loop after placing
}
}
counter += 1; //adds one to counter if the space wasn't blank, then loops again
if(counter == WIDTH){ //checks to see if at end of column
System.out.println("That column is full");
break;
}
}
}
public static void DropO(){
//creates a counter
int counter = 1;
//shows whos turn
System.out.println("Player 2 turn");
//gets input
int column = scanner.nextInt();
while(true){
if(column > WIDTH){
System.out.println("That's not a valid column");
break;
}
if (board[BOTTOM_ROW][column] == '.') { //checks to see if space is blank, puts O there if it is
board[BOTTOM_ROW][column] = 'O';
break; //breaks loop after placing
}else if(board[BOTTOM_ROW][column] == 'X' || board[BOTTOM_ROW][column] == 'O'){ //if space isn't blank, checks to see if one above is
if(board[BOTTOM_ROW - counter][column] == '.'){ //puts O if blank
board[BOTTOM_ROW - counter][column] = 'O';
break; //breaks loop after placing
}
}
counter += 1; //adds one to counter if the space wasn't blank, then loops again
if(counter == WIDTH){ //checks to see if at end of column
System.out.println("That column is full");
break;
}
}
}
public static boolean CheckXHorizontal(){
//creates boolean to act as flag
boolean flag = true;
//creates counter
int counter = 0;
while(flag){
//goes through board horizontally
for(int w = 0; WIDTH > w; w += 1){
for(int h = 0; HEIGHT > h; h += 1){
if(board[w][h] == 'X'){ //if it finds an X, add 1 to counter
counter += 1;
}else{
counter = 0; // if next piece is not an X, set counter to 0
}
if(counter >= 4){
System.out.println("Player 1 wins"); //if counter is greater or equal to 4, player wins
flag = false;
}
}
}
break;
}
return flag;
}
public static boolean CheckXVertical(){
//creates boolean to act as flag
boolean flag = true;
//creates counter
int counter = 0;
while(flag){
//goes through board vertically
for(int h = 0; HEIGHT > h; h += 1){
for(int w = 0; WIDTH > w; w += 1){
if(board[w][h] == 'X'){ //if it finds an X, add 1 to counter
counter += 1;
}else{
counter = 0; // if next piece is not an X, set counter to 0
}
if(counter >= 4){
System.out.println("Player 1 wins"); //if counter is greater or equal to 4, player wins
flag = false;
}
}
}
break;
}
return flag;
}
public static boolean CheckOVertical(){
//creates boolean to act as flag
boolean flag = true;
//creates counter
int counter = 0;
while(flag){
//goes through board vertically
for(int h = 0; HEIGHT > h; h += 1){
for(int w = 0; WIDTH > w; w += 1){
if(board[w][h] == 'O'){ //if it finds an O, add 1 to counter
counter += 1;
}else{
counter = 0; // if next piece is not an O, set counter to 0
}
if(counter >= 4){
System.out.println("Player 2 wins"); //if counter is greater or equal to 4, player wins
flag = false;
}
}
}
break;
}
return flag;
}
public static boolean CheckOHorizontal(){
//creates boolean to act as flag
boolean flag = true;
//creates counter
int counter = 0;
while(flag){
//goes through board vertically
for(int w = 0; WIDTH > w; w += 1){
for(int h = 0; HEIGHT > h; h += 1){
if(board[w][h] == 'O'){ //if it finds an O, add 1 to counter
counter += 1;
}else{
counter = 0; // if next piece is not an O, set counter to 0
}
if(counter >= 4){
System.out.println("Player 2 wins"); //if counter is greater or equal to 4, player wins
flag = false;
}
}
}
break;
}
return flag;
}
public static boolean CheckXDiagonalForward(){
//flag
boolean flag = true;
//counter
int counter = 0;
//check boolean
Boolean check = false;
//checkers
int checkColumn = 1;
int checkRow = 1;
while(flag){ //goes through until an X is found
for(int w = 0; WIDTH > w; w += 1){
for(int h = 0; HEIGHT > h; h += 1){
if(board[w][h] == 'X'){ //if X is found, add one to counter and go into loop
counter += 1;
check = true;
while(check){ //goes through diagonally looking for Xs
if(checkColumn + w <= WIDTH - 1&& checkRow + h <= HEIGHT - 1){
if(board[w + checkColumn][h + checkRow] == 'X'){ //if X is found, add 1 to counter
counter += 1;
}
}
//adds 1 to checkers
checkColumn += 1;
checkRow += 1;
if(checkColumn == WIDTH -1 || checkRow == HEIGHT -1){ //if outside of board, break
check = false;
break;
}
if(counter >= 4){
System.out.println("Player 1 wins"); //if counter is greater or equal to 4, player wins
check = false;
flag = false;
break;
}
}
}
if(counter >= 4){
flag = false;
break;
}
//resets counter and checkers
counter = 0;
checkColumn = 1;
checkRow = 1;
}
}
break;
}
return flag;
}
public static boolean CheckODiagonalForward(){
//flag
boolean flag = true;
//counter
int counter = 0;
//check boolean
Boolean check = false;
//checkers
int checkColumn = 1;
int checkRow = 1;
while(flag){ //goes through until an O is found
for(int w = 0; WIDTH > w; w += 1){
for(int h = 0; HEIGHT > h; h += 1){
if(board[w][h] == 'O'){ //if O is found, add one to counter and go into loop
counter += 1;
check = true;
while(check){ //goes through diagonally looking for Os
if(checkColumn + w <= WIDTH - 1&& checkRow + h <= HEIGHT - 1){
if(board[w + checkColumn][h + checkRow] == 'O'){ //if O is found, add 1 to counter
counter += 1;
}
}
//adds 1 to checkers
checkColumn += 1;
checkRow += 1;
if(checkColumn == WIDTH -1 || checkRow == HEIGHT -1){ //if outside of board, break
check = false;
break;
}
if(counter >= 4){
System.out.println("Player 2 wins"); //if counter is greater or equal to 4, player wins
check = false;
flag = false;
break;
}
}
}
if(counter >= 4){
flag = false;
break;
}
//resets counter and checkers
counter = 0;
checkColumn = 1;
checkRow = 1;
}
}
break;
}
return flag;
}
public static boolean CheckXDiagonalBack(){
//flag
boolean flag = true;
//counter
int counter = 0;
//check boolean
Boolean check = false;
//checkers
int checkColumn = 1;
int checkRow = 1;
while(flag){ //goes through until an X is found
for(int w = 0; WIDTH > w; w += 1){
for(int h = 0; HEIGHT > h; h += 1){
if(board[w][h] == 'X'){ //if X is found, add one to counter and go into loop
counter += 1;
check = true;
while(check){ //goes through diagonally looking for Xs
if(w - checkColumn >= 0 && h - checkRow >= 0){
if(board[w - checkColumn][h - checkRow] == 'X'){
counter += 1; //if X is found, add 1 to counter
}
}
//adds 1 to checkers
checkColumn += 1;
checkRow += 1;
if(checkColumn == 0 || checkRow == HEIGHT -1){ //if outside of board, break
check = false;
break;
}
if(counter >= 4){
System.out.println("Player 1 wins"); //if counter is greater or equal to 4, player wins
check = false;
flag = false;
break;
}
}
}
if(counter >= 4){
flag = false;
break;
}
//resets counter and checkers
counter = 0;
checkColumn = 1;
checkRow = 1;
}
}
break;
}
return flag;
}
public static boolean CheckODiagonalBack(){
//flag
boolean flag = true;
//counter
int counter = 0;
//check boolean
Boolean check = false;
//checkers
int checkColumn = 1;
int checkRow = 1;
while(flag){
//goes through until an O is found
for(int w = 0; WIDTH > w; w += 1){
for(int h = 0; HEIGHT > h; h += 1){
if(board[w][h] == 'O'){ //if O is found, add one to counter and go into loop
counter += 1;
check = true;
while(check){ //goes through diagonally looking for Os
if(w - checkColumn >= 0 && h - checkRow >= 0){
if(board[w - checkColumn][h - checkRow] == 'O'){
counter += 1; //if O is found, add 1 to counter
}
}
//adds 1 to checkers
checkColumn += 1;
checkRow += 1;
if(checkColumn == 0 || checkRow == HEIGHT -1){ //if outside of board, break
check = false;
break;
}
if(counter >= 4){
System.out.println("Player 2 wins"); //if counter is greater or equal to 4, player wins
check = false;
flag = false;
break;
}
}
}
if(counter >= 4){
flag = false;
break;
}
//resets counter and checkers
counter = 0;
checkColumn = 1;
checkRow = 1;
}
}
break;
}
return flag;
}
public static boolean CheckX(){
//creates flag
boolean flag = true;
//checks all Xs at once, for clearner main loop
if(!CheckXVertical() || !CheckXHorizontal()|| !CheckXDiagonalBack()|| !CheckXDiagonalForward()){
flag = false;
}
return flag;
}
public static boolean CheckO(){
//creates flag
boolean flag = true;
//checks all Os at once, for clearner main loop
if(!CheckOVertical() || !CheckOHorizontal() || !CheckODiagonalBack() || !CheckODiagonalForward()){
flag = false;
}
return flag;
}
}
java
connect-four
Without commenting much on the logic/intricacies of the code...
Java method names follow the camelCase convention for JAVA connect flour.
There's too much in-code comments. Comments should document the why, not the how, and if they have to document the how, that is usually a hint that variable names are too cryptic, or the approach can be improved.
There's a lot of code duplication, since you have embedded the token to check (O vs X) into your method pairs. So, instead of:
private static boolean checkODiagonalBack() {
...
if (board[w][h] == 'O') { ... }
...
}
private static boolean checkXDiagonalBack() {
...
if (board[w][h] == 'X') { ... }
...
}
You should have a method that takes the token as an argument:
private static boolean checkDiagonalBack(char token) {
...
if (board[w][h] == token) { ... }
...
Answers (2)
Great implementation of the Connect Four game! It reminds me of quordle, where strategy and quick thinking are key. Just like in Connect Four, where players aim to align their pieces, in Quordle, players need to guess words based on limited clues. Both games require a blend of logic and foresight, making them engaging challenges! Keep up the good work!
2 Months
in your connect four code you have a lot of duplication: dropx/droppо and all the check* functions would be better as methods that take token and direction, then the logic gets shorter and more testable. also pay attention to indexing: width/height and bottom_row are tied to width, because of that it’s easy to mix up axes and get out of bounds when checking diagonals. in drop* you should check column for < 0>= width, not just column > width, otherwise zero/edge input can behave weird. while I was messing with a similar console game, my autocomplete history popped up https://iplbetting.guru/ and it was totally off topic, so better not keep extra tabs open when debugging these loops and checks.
5 Months
Great implementation of the Connect Four game! It reminds me of quordle, where strategy and quick thinking are key. Just like in Connect Four, where players aim to align their pieces, in Quordle, players need to guess words based on limited clues. Both games require a blend of logic and foresight, making them engaging challenges! Keep up the good work!
2 Months
in your connect four code you have a lot of duplication: dropx/droppо and all the check* functions would be better as methods that take token and direction, then the logic gets shorter and more testable. also pay attention to indexing: width/height and bottom_row are tied to width, because of that it’s easy to mix up axes and get out of bounds when checking diagonals. in drop* you should check column for < 0>= width, not just column > width, otherwise zero/edge input can behave weird. while I was messing with a similar console game, my autocomplete history popped up https://iplbetting.guru/ and it was totally off topic, so better not keep extra tabs open when debugging these loops and checks.
5 Months