how to save data on cellphone unity android

 using System.IO  public class scoreFile {     private int[] level;     private bool[] completed;     private float[] completionTime;      private string[] scores;      private string fileName;       //This class stores information for each of the levels.     public scoreFile(int num)     {         fileName = "scores.txt";          try         {              if (!File.Exists(fileName))             {                  level = new int[num];                 completionTime = new float[num];                 completed = new bool[num];                 scores = new string[num];                  Debug.Log("Opened file!");                  for (int i = 0; i < num; i++)                 {                     level[i] = i + 1;                     completionTime[i] = 0;                     completed[i] = false;                      scores[i] = level[i] + " " + 0 + " " + completionTime[i];                 }                  Debug.Log("About to write into file!");                 File.WriteAllLines(fileName, scores);             }              else             {                 Debug.Log("File is exist! Loading!");                 loadFile();             }         }          catch (System.Exception e)         {             Debug.Log(e);         }     }      public bool isComplete(int i) { return completed[i]; }     public int levels(int i) { return level[i - 1] + 1; }     public float timeScore(int i) { return completionTime[i]; }        public void loadFile()     {         Debug.Log("Reading");         string[] levelsInfo = File.ReadAllLines(fileName);          int num = levelsInfo.Length;          level = new int[num];         completionTime = new float[num];         completed = new bool[num];          for (int i = 0; i < num; i++)         {             //Debug.Log(levelsInfo[i]);             string str = levelsInfo[i];             level[i] = (int)int.Parse(str.Substring(0, 1));             int f = int.Parse(str.Substring(2, 1));             if (f == 0)                 completed[i] = false;             else                 completed[i] = true;             completionTime[i] = (float)float.Parse(str.Substring(4));         }     } }