package PrintGame;
//------------------------------------------------------------
/**
 * Implementation of a two dimensional field
 */

public class Field
{
      /** the internal store for the field */
  protected Object[][] field_;

//------------------------------------------------------------
/**
 * standard constructor
 * @param rows the number of rows of the field
 * @param cols the number of columns of the field
 * @exception IllegalArgumentException thrown if either rows or cols
 * is < 0
 */

  public Field(int rows, int cols)
    throws IllegalArgumentException
  {
    if ((rows < 0) || (cols < 0))
      throw(new IllegalArgumentException("rows or cols < 0"));
        // don't allocate an array with either rows or cols being 0
    if ((rows > 0) && (cols > 0))
      field_ = new Object[rows][cols];
  }

//------------------------------------------------------------
/**
 * returns an element as defined by the given indices
 * @param row the row of the desired element
 * @param col the column of the desired element
 * @exception IndexOutOfBoundsException thrown if the index is outside
 * of the allocated range
 */

  private Object getElement(int row,int col)
    throws IndexOutOfBoundsException
  {
    if (field_ == null)
      throw(new IndexOutOfBoundsException("field has zero size"));
    return(field_[row][col]);
  }

//------------------------------------------------------------
/**
 * returns the number of allocated rows
 * @return the number of allocated rows
 */

  public int getNumRows()
  {
    if (field_ == null)
      return(0);
    return(field_.length);
  }

//------------------------------------------------------------
/**
 * returns the number of allocated columns
 * @return the number of allocated columns
 */

  public int getNumCols()
  {
    if (field_ == null)
      return(0);
    return(field_[0].length);
  }

//------------------------------------------------------------
/**
 * standard toString method for debugging
 * @return info about the field in string-format
 */

  public String toString()
  {
    if (field_ == null)
      return("field with zero size");
    return("rows: " + field_.length + ", cols: " +
           field_[0].length);
  }

}