Java flashing

SettingsActivity.java

private void flashFromJava(final IHasKKM kkm, final String fileName) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    if (runCommand("EC 01") != 0) {
                        handler.post(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(getApplicationContext(), "Error running EC 01", Toast.LENGTH_SHORT).show();
                            }
                        });
                        return;
                    }

                    if (runCommand("EC 00") != 0) {
                        handler.post(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(getApplicationContext(), "EC 00 вернула не ноль", Toast.LENGTH_SHORT).show();
                            }
                        });
                        return;
                    }


                    if (kkm.getKKM().CheckDownloadMode() != 0) {
                        handler.post(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(getApplicationContext(), "Error checking download mode" +
                                        "", Toast.LENGTH_SHORT).show();
                            }
                        });
                        return;
                    }


                    byte[] buffer = new byte[BUFFER_SIZE];
                    File file = new File(Environment.getExternalStorageDirectory(), fileName);
                    
                    InputStream stream = new BufferedInputStream(new FileInputStream(file));
                    int bytesRead = stream.read(buffer);
                    
                    final int totalBlocks = (int) file.length() / BUFFER_SIZE + 1;

                    kkm.getKKM().ExitDownloadMode();


                    if (kkm.getKKM().StartFlashing(totalBlocks) != 0) {//runCommand("EC 03 41 1e") != 0) {
                        handler.post(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(getApplicationContext(), "Error running EC 03 41 1e", Toast.LENGTH_SHORT).show();
                            }
                        });
                        return;
                    }


                    int i = 0;
                    


                    while (bytesRead != -1) {

                        String str = "EC 04 " + getHexCounter(i) + ' ' + toHexString(buffer, bytesRead);
                        

                        final int response = kkm.getKKM().WriteBlock(buffer, bytesRead, i, str);
                        i++;

                        if (response != 0) {
                            handler.post(new Runnable() {
                                @Override
                                public void run() {
                                    Toast.makeText(getApplicationContext(), "ERROR WRITING (" + response + ")", Toast.LENGTH_LONG).show();
                                }
                            });
                            break;
                        }
                        bytesRead = stream.read(buffer);
                    }


                    if (kkm.getKKM().CheckFlashingSuccess() != 0) {
                        handler.post(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(getApplicationContext(), "Error checking flash status!", Toast.LENGTH_SHORT).show();
                            }
                        });
                        return;
                    }

                    kkm.getKKM().FinishFlashing();
                    handler.post(new Runnable() {
                        @Override
                        public void run() {
                            Toast.makeText(getApplicationContext(), "Done!", Toast.LENGTH_SHORT).show();
                        }
                    });
                } catch (final Exception ex) {
                    handler.post(new Runnable() {
                        @Override
                        public void run() {
                            Toast.makeText(getApplicationContext(), "Exception! " + ex.getMessage(), Toast.LENGTH_SHORT).show();
                        }
                    });
                }
            }
        }).start();
    }