to perform file operation

fileoperation.groovy

File f = new File("helloworld.txt")

FileOutputStream fos = new FileOutputStream(historyFile, true)
DataOutputStream dos = new DataOutputStream(fos)
BufferedWriter bw = new BufferedWriter((new OutputStreamWriter(dos)))

Date today = new Date()

for(int i = 10; i >= 0; i--) {
  Date anotherDay = new Date()
	anotherDay.date = today.date + i;
	bw.writeLine(anotherDay.format(dateFormat) + "," // Date
			+ Math.round( Math.random() * 100 )) // Random number
}
bw.flush()
dos.close()

FileInputStream fio = new FileInputStream(historyFile)
DataInputStream dis = new DataInputStream(fio)
BufferedReader br = new BufferedReader(new InputStreamReader(dis))

String strLine;
while ((strLine = br.readLine()) != null)   {
	logger.info(strLine);
}

dis.close()