How to open file with any exetension in Android?

The following code will work for every file type:

try {
    Intent intent = new Intent(Intent.ACTION_VIEW);
    intent.setDataAndType(Uri.fromFile(file), fileMimeType);
    startActivity(intent);
} catch (ActivityNotFoundException e) {
    // no Activity to handle this kind of files
}

Of course, there should be an Activity in the system that knows how to handle the file of a certain type. Hope this helps.