isValid Method for chess

/**
 * A player of a chess game.
 *
 * @author Zachary Kurmas
 */
public enum Player {
   BLACK, WHITE;

   /**
    * Return the {@code Player} whose turn is next.
    *
    * @return the {@code Player} whose turn is next
    */
   public Player next() {
      return this == BLACK ? WHITE : BLACK;
   }
}
public class Move {

   public int fromRow, fromColumn, toRow, toColumn;

   public Move(int fromRow, int fromColumn, int toRow, int toColumn) {
      this.fromRow = fromRow;
      this.fromColumn = fromColumn;
      this.toRow = toRow;
      this.toColumn = toColumn;
   }
}
public class Pawn extends ChessPiece {

	protected Pawn(Player player) {
		super(player);
		
	}
	public String type(){
		return "Pawn";
	}
	public boolean isValidMove(Move move, IChessPiece[][] board){
		if(super.isValidMove(move, board) == false){
			return false;
		}
		if (move.toRow != move.fromRow+1){
			return false;
			
		}
				
		
		
	}

}





public abstract  class  ChessPiece implements IChessPiece {
	/**  */
	private Player owner;
	
	
	 /**
	    * Return the player that owns this piece.
	    *
	    * @return the player that owns this piece.
	    */
	protected ChessPiece(Player player) {
		this.owner = player;
		
	}

//	public abstract String type()

	/* (non-Javadoc)
	 * @see chess.IChessPiece#player()
	 */
	@Override
	public Player player() {
		if (owner == Player.BLACK) {
			return owner;
		}
		if (owner == Player.WHITE) {
			return owner;
		} else
			return null;

	}
	

	/*
	 * (non-Javadoc)
	 * 
	 * @see chess.IChessPiece#isValidMove(chess.Move, chess.IChessPiece[][])
	 */
	@Override
	public boolean isValidMove(Move move, IChessPiece[][] board) {
		if (move.toRow == move.fromRow && move.fromColumn == move.toColumn) {
			return false;
		}
		  
		IChessPiece firstPiece = board[move.toRow][move.toColumn];
		IChessPiece secondPiece = board[move.fromRow][move.fromColumn];
		 if( firstPiece != null && firstPiece == secondPiece ){
			 return false;
		 }
		 else
			return board[move.fromRow][move.fromColumn].equals(this.owner);

	}
	
	

	
	public abstract String type();
}
public interface IChessPiece {

   /**
    * Return the player that owns this piece.
    *
    * @return the player that owns this piece.
    */
   Player player();

   /**
    * Return the type of this piece ("King", "Queen", "Rook", etc.).  Note:  In this case "type" refers to the game
    * of chess, not the type of the Java class.
    *
    * @return the type of this piece
    */
   String type();

   /**
    * Returns whether the piece at location {@code [move.fromRow, move.fromColumn]} is allowed to move to location
    * {@code [move.fromRow, move.fromColumn]}.
    *
    * Note:  Pieces don't store their own location (because doing so would be redundant).  Therefore,
    * the {@code [move.fromRow, move.fromColumn]} component of {@code move} is necessary.
    * {@code this} object must be the piece at location {@code [move.fromRow, move.fromColumn]}.
    * (This method makes no sense otherwise.)
    *
    * @param move  a {@link Move} object describing the move to be made.
    * @param board the {@link ChessBoard} in which this piece resides.
    * @return {@code true} if the proposed move is valid, {@code false} otherwise.
    * @throws IndexOutOfBoundsException if either {@code [move.fromRow, move.fromColumn]} or {@code [move.toRow,
    *                                   move.toColumn]} don't represent valid locations on the board.
    * @throws IllegalArgumentException  if {@code this} object isn't the piece at location {@code [move.fromRow, move.fromColumn]}.
    */
   boolean isValidMove(Move move, IChessPiece[][] board);
}