ChessBoard

```
public class ChessBoard
```
ChessBoard.java A class to model a chess board

Method Summary

Methods
Modifier and Type	Method and Description
`int`	`currentTurn()` Return the number of turns that have been completed.
`Piece`	`pieceAt(int row, int column)` Return the piece at an indicated position, if any.
`void`	`placePiece(Piece piece, int row, int column)` Add a chess piece to the board at the indicated empty position.
`void`	`replacePiece(Piece oldPiece, Piece newPiece, int row, int column)` Replace a piece on the board with a new piece.

- Method Detail
  - currentTurn
```
public int currentTurn()
```
    Return the number of turns that have been completed.
    
    Returns:
    The number of the current turn.
  - pieceAt
```
public Piece pieceAt(int row,
            int column)
```
    Return the piece at an indicated position, if any.
    
    Parameters:
    row - The vertical position in which to look
    column - The horizontal position in which to look
    
    Returns:
    The piece, if any, at the indicated position.
  - placePiece
```
public void placePiece(Piece piece,
              int row,
              int column)
```
    Add a chess piece to the board at the indicated empty position.
    
    Parameters:
    piece - The piece to add to the board
    row - The vertical position in which to place the piece
    column - The horizontal position in which to place the piece
    
    PRECONDITION:
    The location specified is currently empty.
  - placePiece
```
public void replacePiece(Piece oldPiece,
              Piece newPiece,
              int row,
              int column)
```
    Replace a piece on the board with a new piece.
    
    Parameters:
    oldPiece - The piece to be replaced
    newPiece - The piece with which to replace it
    row - The vertical position in which to place the piece
    column - The horizontal position in which to place the piece
    
    PRECONDITION:
    The location specified is currently occupied by oldPiece.