package com.application.Database;

import com.mongodb.*;
import javafx.scene.control.PasswordField;
import javafx.scene.control.TextField;


import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.LogManager;
import java.util.logging.Logger;

import static jdk.nashorn.internal.runtime.regexp.joni.Syntax.Java;

public class DBEmployees {
    ppublic static boolean authenticate(String username, String password){
    boolean flag;
    BasicDBObject andQuery = new BasicDBObject();
    List<BasicDBObject> obj = new ArrayList<>();
    obj.add(new BasicDBObject("email", username));
    obj.add(new BasicDBObject("password", password));
    andQuery.put("$and", obj);
    DBCursor cursor = collection.find(andQuery);
    ArrayList<BasicDBObject> x = new ArrayList<>();
    while (cursor.hasNext()) {
        x.add((BasicDBObject) cursor.next());
        cursor.next();
    } if(x.size()==1){
        flag = true;
    }
    else {
        flag = false;
    }
    return flag;
}


    final static Logger globalLogger = Logger.getLogger(java.util.logging.Logger.GLOBAL_LOGGER_NAME);


    private static MongoClient mongoClient = new MongoClient( "localhost" , 27017 );

    private static DB db = mongoClient.getDB("mydb");
    private static DBCollection collection = db.getCollection("Employees");

    public static void main(String[] args)  {

        globalLogger.setLevel(java.util.logging.Level.OFF);

        BasicDBObject employee1  =  new BasicDBObject("name","Damith Asanka")
                    .append("age","34")
                    .append("email","damith.a@ugnip.ac.lk")
                    .append("staff type","specific")
                    .append("password","123456789B")
                    .append("space type","office_1")
                    .append("building number","2");
            collection.insert(employee1);
            BasicDBObject employee2 = new BasicDBObject("name","Yureni Noshika")
                    .append("age","18")
                    .append("email","yureni.n@ugnip.ac.lk")
                    .append("staff type","authentic")
                    .append("password","1239256789A")
                    .append("space type","studio_3")
                    .append("building number","1");
            collection.insert(employee2);
            BasicDBObject employee3 = new BasicDBObject("name","Niroshan Dickwella")
                    .append("age","25")
                    .append("email","niroshan.d@ugnip.ac.lk")
                    .append("staff type","specific")
                    .append("password","123456XyZa")
                    .append("space type","office_2")
                    .append("building number","2");
            collection.insert(employee3);
            BasicDBObject employee4 = new BasicDBObject("name","Thumindu Dodantenna")
                    .append("age","19")
                    .append("email","thumindu.d@ugnip.ac.lk")
                    .append("staff type","specific")
                    .append("password","456dm2934")
                    .append("space type","office_6")
                    .append("building number","1");
            collection.insert(employee4);
        BasicDBObject employee5 = new BasicDBObject("name","Kalana Jayanath")
                .append("age","19")
                .append("email","kalana.j@ugnip.ac.lk")
                .append("staff type","specific")
                .append("password","456d11112934")
                .append("space type","office_4")
                .append("building number","1");
        collection.insert(employee5);
    }
}

package com.applicationLoginInterface;


import javafx.fxml.FXML;

import javafx.scene.control.PasswordField;
import javafx.scene.control.TextField;

import com.application.Database.*;


import java.io.IOException;


public class ControllerLogin {


@FXML private PasswordField loginPassword;
@FXML private TextField loginID;


public static void main(String[] args){

}

@FXML private void loginBtnClicked() throws IOException {

    String username = loginID.getText();
    String password = loginPassword.getText();
    if(DBEmployees.authenticate(username,password)){
        System.out.println("Success");
    }
    else {
        System.out.println("Incorrect login credentials");
    }

  }
}

...
obj.add(new BasicDBObject("email", username.getText()));
obj.add(new BasicDBObject("password", password.getText()));
...