public boolean bishopMove(int startRow, int startCol, int endRow, int endCol)
	{
		Piece piece = checker[startRow][startCol];
		Piece endTile = checker[endRow][endCol];
				
		if(endTile == null  ||  endTile.alligence != piece.alligence)	//only move or move and attack
		{
			if(Math.abs(endCol-startCol) == Math.abs(endRow-startRow))	//diagonal movement
			{
				int colIndexPar;	//horizontal direction
				if(endCol>startCol)
				{
					colIndexPar = 1;
				}
				else
				{
					colIndexPar = -1;
				}
				
				int rowIndexPar;	//vertical direction
				if(endRow>startRow)
				{
					rowIndexPar = 1;
				}
				else
				{
					rowIndexPar = -1;
				}
				
				for(int i=1; i<Math.abs(endCol-startCol); i++)	//check for free path
				{
					if(checker[startRow+i*rowIndexPar][startCol+i*colIndexPar] != null)
					{
						return false;
					}
				}
				return true;
			}
			else	//illegal movement
			{
				return false;
			}
		}
		else	//tile occupied by ally
		{
			return false;
		}
	}