ShareActivity.java

void onCreate (Bundle savedInstanceState) {
    
    // Get intent, action and MIME type
    Intent intent = getIntent();
    String action = intent.getAction();
    String type = intent.getType();

    if (Intent.ACTION_SEND.equals(action) && type != null) {
        if ("application/pdf".equals(type)) {
            handlePDF(intent); // Handle text being sent
        } 
    } else if (Intent.ACTION_SEND_MULTIPLE.equals(action) && type != null) {
        if (type.startsWith("application/pdf")) {
           // Handle multiple pdfs being sent
        }
    } else {
        // Handle other intents, such as being started from the home screen
    }
}


void handlePDF(Intent intent) {
    Uri pdfUri = (Uri) intent.getParcelableExtra(Intent.EXTRA_STREAM);
    if (pdfUri != null) {

        // TODO: Use your server-side here to save. 

    }
}