Mineswipper solution, enhancement to https://gist.github.com/hgmiguel/ac95336b805d22c97f6a

mineswipper.groovy

file = new File(args[0])

board = [][]
file.eachWithIndex {obj, i ->
  if (i == 0) {
    (rows, columns) = obj.split(" ")*.toInteger()
  } else {
     board << ([0] << obj.collect{ it == '*'?'*':0 }  << [0]).flatten()
  }
}

zero_row = (0..columns+1).collect {0}

board.add(0, zero_row)
board << zero_row

def isMine(row, col) {
  board[row][col] == '*'
}

(1..rows).each { row ->
  (1..columns).each { column ->
    if(!isMine(row, column)) {

      neighbours = [[r:row+1, c:column  ],
                    [r:row-1, c:column  ],
                    [r:row  , c:column+1],
                    [r:row  , c:column-1],
                    [r:row+1, c:column+1],
                    [r:row-1, c:column-1],
                    [r:row+1, c:column-1],
                    [r:row-1, c:column+1]]
      
      board[row][column] += neighbours.findAll { isMine(it['r'], it['c'])}.size
    }
  }
}

board[1..rows].each {row ->
   println row.collect { it.toString() }.join()[1..columns]
}