read_CPU_usage.java

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 (float) 0;
    }