Question

I have to create a tic tac toe board using the following classes. The main function is already been made as another java file and presented below to test if it works or not. 

Using these methods as the public class:
public TTTBoard(int size) //Present DEFAULT_SIZE = 3. Throw IllegalArgumentException if the size is less than 1.
public TTTBoard() 
public char get(int r, int c) //Throw IndexOutOfBoundsException if out of bounds
public void set(int r, int c, char ch) //Char can be anything besides "O" and "X" 
public int size() //Flexible in size
public char winner() //Decide winner from Horizontal, Vertical, both Front Diagonal and Back Diagonal
public String toString() //Draw the board

Using this as the main testing function. Final result will present "pass" if the board works:
 
public class TTTBoardTester {

    public static void main(String[] args) {
        // Code passes unless we find a problem
        boolean pass = true;
        
        // Test existence of class constant
        pass = pass && (TTTBoard.DEFAULT_SIZE == 3);
        
        // Test default board creation, legal set/get, toString, winners
        TTTBoard b = new TTTBoard();
        pass = pass && (b.winner()==' ');
        b.set(0,2,'X');
        b.set(1,1,'X');
        b.set(2,0,'X');
        b.set(2,2,'X');
        pass = pass && (b.get(2,2)=='X');
        pass = pass && (b.get(2,1)==' ');
        String expected = " | |X\n-+-+-\n |X| \n-+-+-\nX| |X";
        pass = pass && (b.toString().indexOf(expected)==0);
        pass = pass && (b.winner()=='X');
        b.set(1,1,' ');
        b.set(1,2,'X');
        expected = " | |X\n-+-+-\n | |X\n-+-+-\nX| |X";
        pass = pass && (b.toString().indexOf(expected)==0);
        pass = pass && (b.winner()=='X');
        b.set(2,1,'X');
        b.set(1,2,' ');
        expected = " | |X\n-+-+-\n | | \n-+-+-\nX|X|X";
        pass = pass && (b.toString().indexOf(expected)==0);
        pass = pass && (b.winner()=='X');

        // Test bigger board creation, toString, size, not winner
        b = new TTTBoard(4);
        b.set(0,0,'X');
        b.set(1,1,'X');
        b.set(2,2,'X');
        b.set(0,2,'X');
        b.set(2,0,'X');
        b.set(1,2,'X');
        b.set(2,1,'X');
        b.set(1,3,'X');
        b.set(3,0,'X');
        b.set(0,1,'X');
        expected = "X|X|X| \n-+-+-+-\n |X|X|X\n-+-+-+-\nX|X|X| \n-+-+-+-\nX| | | ";
        pass = pass && (b.toString().indexOf(expected)==0);
        pass = pass && (b.winner()==' ');
        pass = pass && (b.size()==4);
        // Make it a winner
        b.set(3,3,'X');
         pass = pass && (b.winner()=='X');
       
        // Test smaller board creation, toString, not winner
        b = new TTTBoard(2);
        expected = " | \n-+-\n | ";
        pass = pass && (b.toString().indexOf(expected)==0);
        pass = pass && (b.winner()==' ');
        
        // Test exceptions
        try {
            b = new TTTBoard(0);
            pass = false;        // Exception in constructor will bypass this
        }
        catch(IllegalArgumentException e) {
            // Geting here won't change 'pass'
        }
        catch(Exception e) {
            pass = false;
        }
        
        // Print final result
        System.out.println(pass);
    }

}

Answer 1

Given below is the code for the question. Run the TTTBoardTester.java provided by instructor and the output is true... that is all test pass
To indent code in eclipse , select code by pressing ctrl+a and then indent using ctrl+i
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TTTBoard.java
----

public class TTTBoard {
private char[][] board;
public static final int DEFAULT_SIZE = 3;
  
public TTTBoard(int size) //Present DEFAULT_SIZE = 3. Throw IllegalArgumentException if the size is less than 1.
{
if(size < 1)
throw new IllegalArgumentException();
board = new char[size][size];
for(int i = 0; i < size; i++)
for(int j = 0; j < size; j++ )
board[i][j] = ' ';
}

public TTTBoard(){
int size = 3;
board = new char[size][size];
for(int i = 0; i < size; i++)
for(int j = 0; j < size; j++ )
board[i][j] = ' ';

}

public char get(int r, int c) //Throw IndexOutOfBoundsException if out of bounds
{
int s = board.length;
if(!(r >= 0 && c >= 0 && r < s && c < s))
throw new IndexOutOfBoundsException();

return board[r][c];
}

public void set(int r, int c, char ch) //Char can be anything besides "O" and "X"
{
int s = board.length;

if(!(r >= 0 && c >= 0 && r < s && c < s))
throw new IndexOutOfBoundsException();

board[r][c] = ch;
}

public int size() //Flexible in size
{
return board.length;
}

public char winner() //Decide winner from Horizontal, Vertical, both Front Diagonal and Back Diagonal
{
int s = size();
//check Horizontal
for(int r = 0; r < s; r++){
if(board[r][0] != ' '){
boolean won = true;
for(int c = 1; c < s; c++){
if(board[r][c] != board[r][c-1]){
won = false;
break;
}
}

if(won)
return board[r][0];
}
}
//check vertical
for(int c = 1; c < s; c++){
if(board[0][c] != ' '){
boolean won = true;
for(int r = 1; r < s; r++){

if(board[r-1][c] != board[r][c]){
won = false;
break;
}
}

if(won)
return board[0][c];
}
}
  
//check Front diagonal
if(board[0][0] != ' '){
boolean won = true;
for(int i = 1; i < s; i++){
if(board[i-1][i-1] != board[i][i]){
won = false;
break;
}
}
  
if(won)
return board[0][0];
}

//check Back diagonal

if(board[s-1][0] != ' '){
boolean won = true;
for(int r = 1, c = s-2; r < s; r++, c--){
if(board[r-1][c+1] != board[r][c]){
won = false;
break;
}
}
  
if(won)
return board[s-1][0];
}
  
return ' ';
  

}
public String toString() //Draw the board
{
String str = "";
int s = size();
for(int i = 0; i < s; i++){
for(int j = 0; j < s; j++){
if(j != 0)
str += "|";
str += board[i][j];
  
}
str += "\n";
for(int j = 0; j < s-1; j++)
str += "-+";
str += "-\n";
}
return str;
}

}

output
----
true