Android. JNI. how to get username !?

? Offline

Good day. tell me please. How do I know login or e-mail user Android device?

I tried to write on Java(JNI). but the code is not running.

package org.qtproject.example.notification;

import android.app.Notification;
import android.app.NotificationManager;
import android.content.Context;

import android.accounts.AccountManager;
import android.accounts.Account;
import java.util.List;
import java.util.LinkedList;

public class NotificationClient extends org.qtproject.qt5.android.bindings.QtActivity
{
static NotificationManager m_notificationManager;
static Notification.Builder m_builder;
static NotificationClient m_instance;

 static AccountManager manager;
 static Account[] accounts;
 static List<String> possibleEmails;

public NotificationClient()
{
    m_instance = this;
}

public static void notify(String s)
{
    if (m_notificationManager == null) {
        m_notificationManager = (NotificationManager)m_instance.getSystemService(Context.NOTIFICATION_SERVICE);
        m_builder = new Notification.Builder(m_instance);
        m_builder.setSmallIcon(R.drawable.icon);
        m_builder.setContentTitle( getUsername() );
    }

    m_builder.setContentText(s);
    m_notificationManager.notify(1, m_builder.build());
}

public static String getUsername() {

     manager = AccountManager.get(this);
     accounts = manager.getAccountsByType("com.google");
     possibleEmails = new LinkedList<String>();

    for (Account account : accounts) {
      possibleEmails.add(account.name);
    }

    if (!possibleEmails.isEmpty() && possibleEmails.get(0) != null) {
        String email = possibleEmails.get(0);
        String[] parts = email.split("@");

        if (parts.length > 1)
            return parts[0];
    }

    return "null";

}

}

? Offline

i try this too.
but i have: JNI DETECTED ERROR IN APPLICATION: JNI GetStaticMethodID called with pending exception 'java.lang.IllegalArgumentException' thrown in unknown throw location

package org.qtproject.example;

import android.accounts.AccountManager;
import android.accounts.Account;

public class Android_info extends org.qtproject.qt5.android.bindings.QtActivity{

static Android_info m_instance;

public Android_info(){
    m_instance = this;
}

public static String return_mail(){
    AccountManager am = AccountManager.get(m_instance);
    Account[] accounts = am.getAccountsByType("com.google");
    return accounts[0].name;
}

}

? Offline

This post is deleted!

? Offline

this code workink fine on java android. but JNI+Qt its not working.

package org.qtproject.example;

import android.app.Notification;
import android.app.NotificationManager;
import android.content.Context;

import android.accounts.AccountManager;
import android.accounts.Account;

public class Android_info extends org.qtproject.qt5.android.bindings.QtActivity{

static Android_info m_instance;

public Android_info(){
    m_instance = this;
}

public static String return_mail(){
    AccountManager am = AccountManager.get(m_instance);
    Account[] accounts = am.getAccountsByType("com.google");
    return accounts[0].name;
}

}

? Offline

intellij idea output:
java.lang.IllegalStateException: System services not available to Activities before onCreate()

:(