android - System CPU usage in Live wallpaper -

i'm making live wallpaper displays overall cpu usage percentage. i'm using code 1 of questions here. works, wallpaper freezes few seconds because of thread.sleep(). , if remove that, doesn't display correct values. how cpu usage, id doesn't interfere live wallapaper?

    private float readusage() {     try {         randomaccessfile reader = new randomaccessfile("/proc/stat", "r");         string load = reader.readline();          string[] toks = load.split(" ");          long idle1 = long.parselong(toks[5]);         long cpu1 = long.parselong(toks[2]) + long.parselong(toks[3]) + long.parselong(toks[4])               + long.parselong(toks[6]) + long.parselong(toks[7]) + long.parselong(toks[8]);          try {             thread.sleep(360);         } catch (exception e) {}          reader.seek(0);         load = reader.readline();         reader.close();          toks = load.split(" ");          long idle2 = long.parselong(toks[5]);         long cpu2 = long.parselong(toks[2]) + long.parselong(toks[3]) + long.parselong(toks[4])             + long.parselong(toks[6]) + long.parselong(toks[7]) + long.parselong(toks[8]);          return (float)(cpu2 - cpu1) / ((cpu2 + idle2) - (cpu1 + idle1));      } catch (ioexception ex) {         ex.printstacktrace();     }      return 0; }