Android marshmallow request permission?

I am currently working on an application that requires several "dangerous" permissions. So I tried adding "ask for permission" as required in Android Marshmallow(API Level 23), but couldn't find how to do it.

How can I ask for permission using new permission model in my app?

Request runtime permissions from the docs has code examples you can use.

The code snippets in this answer are taken from that document.

Open a Dialog using the code below:

ActivityCompat.requestPermissions(MainActivity.this,
                    new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
                    1);

Get the Activity result as below:

@Override public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
    switch (requestCode) {
        case 1: {

          // If request is cancelled, the result arrays are empty.
          if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                // permission was granted, yay! Do the
                // contacts-related task you need to do.          
            } else {

                // permission denied, boo! Disable the
                // functionality that depends on this permission.
                Toast.makeText(MainActivity.this, "Permission denied to read your External storage", Toast.LENGTH_SHORT).show();
            }
            return;
        }

        // other 'case' lines to check for other
        // permissions this app might request
    } }

More info: https://developer.android.com/training/permissions/requesting.html