Question

 public void onCallStateChanged(int state,String incomingNumber)
{
    System.out.print("\nState :-  "+state);
      switch(state){
        case TelephonyManager.CALL_STATE_IDLE:

            if(flag==true && ringflag == true)
            {
                flag=false;
                ringflag=false;
                System.out.print("\nflag = " + flag);
                System.out.print("\nringflag = " + ringflag);
                stop = System.currentTimeMillis();
                System.out.println("\nTotal time : " +stop);
                System.out.println("\nTotal time : " +(stop - start)/1000);
                System.out.println("\nIDLE : " + incomingNumber);
                long time = (stop - start) / 1000;
                String path = Environment.getExternalStorageDirectory().getAbsolutePath();
                f = new File(path + "/sms.txt");
                if (f.exists()) {
                    try {
                        raf =new RandomAccessFile(f, "rw");
                        long pointer = raf.length();
                        raf.seek(pointer);
                        String data = ":-"+no+","+time;
                        raf.writeBytes(data);
                        raf.close();
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }

                } else {
                    try {
                        raf = new RandomAccessFile(f,"rw");
                        String data = ":-"+no+","+time;
                        raf.writeBytes(data);
                        raf.close();
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        break;
        case TelephonyManager.CALL_STATE_OFFHOOK:
            if(ringflag == true)
            {
                System.out.println("OFFHOOK :- " + incomingNumber);
                start = System.currentTimeMillis();
                System.out.print("\nStart is :-" + start);
                flag=true;
            }
        break;
        case TelephonyManager.CALL_STATE_RINGING:
            no = incomingNumber;
            System.out.println("Ringing : " + incomingNumber);
            ringflag= true;
        break;
      }
  }

Answer 1

I can answer the first part of your question

To get the call duration it is important to access the Call Logs.

Using the information given in CallLog.Calls, It can be done like below:

          Uri allCalls = Uri.parse("content://call_log/calls");
          Cursor c = managedQuery(allCalls, null, null, null, null);
            for(String colName : c.getColumnNames())
                Log.v(TAG, "Column Name: " + colName);

            if (c.moveToFirst())
            {
               do{
                   String id = c.getString(c.getColumnIndex(CallLog.Calls._ID));
                   String num = c.getString(c.getColumnIndex(CallLog.Calls.NUMBER));
                   int type = Integer.parseInt(c.getString(c.getColumnIndex(CallLog.Calls.TYPE)));

                   String duration = c.getString(c.getColumnIndex(CallLog.Calls.DURATION));
                   System.out.println("call time duration is"+duration);

                    switch (type)
                    {
                        case 1: Log.v(TAG, id + ", " +num + ": INCOMING") ; break;
                        case 2: Log.v(TAG, id + ", " +num + ": OUTGOING") ;break;
                        case 3: Log.v(TAG, id + ", " +num + ": MISSED") ; break;
                    }
               } while (c.moveToNext());
            }

Refer this nice blog post for more information.