How to login multiple SAP system using SAP jco

I am new to SAP JCo I have requirement to call multiple SAP System using SAP Jco. But I am unable to connect multiple sap system at the same time......

Here is code :

package com.sap.test;


import java.util.Properties;

import com.sap.conn.jco.JCoDestination;
import com.sap.conn.jco.JCoDestinationManager;
import com.sap.conn.jco.JCoException;
import com.sap.conn.jco.JCoRepository;
import com.sap.conn.jco.ext.DestinationDataProvider;
import com.sap.conn.jco.ext.Environment;
import com.sap.utils.MyDestinationDataProvider;
import com.sap.utils.SapSystem;


public class TestMultipleSAPConnection {

    public static Properties properties;
    public static JCoDestination dest = null;
    public static JCoRepository repos = null;
    public static SapSystem system = null;
    String SAP_SERVER = "SAP_SERVER";
    MyDestinationDataProvider myProvider = null;



    public static void main(String[] args) throws JCoException {            
        getConnection_CRM();
        getConnection_R3();     
    }


public static JCoDestination getConnection_R3() {

        boolean connR3_flag = true;
        JCoDestination dest = null;
        JCoRepository repos = null;

        String SAP_SERVER = "SAP_SERVER";
        Properties properties = new Properties();
        SapSystem system = new SapSystem();

        system.setClient("100");
        system.setHost("r3devsvr.myweb.com");
        system.setLanguage("en");
        system.setSystemNumber("00");
        system.setUser("SAP-R3-USER");
        system.setPassword("init1234");

        properties.setProperty("jco.client.ashost", system.getHost());
        properties.setProperty("jco.client.sysnr", system.getSystemNumber());
        properties.setProperty("jco.client.client", system.getClient());
        properties.setProperty("jco.client.user", system.getUser());
        properties.setProperty("jco.client.passwd", system.getPassword());
        properties.setProperty("jco.client.lang", system.getLanguage());
        System.out.println("******* Connection Parameter Set *******");
        MyDestinationDataProvider myProvider = new MyDestinationDataProvider();
        System.out.println("******* Destination Provider Set *******");
        myProvider.changePropertiesForABAP_AS(properties);
        if (!Environment.isDestinationDataProviderRegistered()) {
            System.out.println("Registering Destination Provider R3");
            Environment.registerDestinationDataProvider((DestinationDataProvider) myProvider);
        }else{
            System.out.println("Destination Provider already set..R3");
            connR3_flag = false;
        }
        try {
            dest = JCoDestinationManager.getDestination((String) SAP_SERVER);
            repos = dest.getRepository();
            if (repos == null) {
                System.out.println("Repos is null.....");
            } else {
                System.out.println("Repos is not null.....");
            }
            System.out.println("After getting repos...");
            if(connR3_flag){
               System.out.println("R3 Connection Successfull...");
            }
        } catch (Exception ex) {
            System.out.println(ex);
        }
        return dest;
    }

    public static JCoDestination getConnection_CRM() {
        boolean connCRM_flag = true;
        JCoDestination dest = null;
        JCoRepository repos = null;

        String SAP_SERVER = "SAP_SERVER";
        Properties properties = new Properties();
        SapSystem system = new SapSystem();

        system.setClient("200");
        system.setHost("crmdevsvr.myweb.com");
        system.setLanguage("en");
        system.setSystemNumber("00");
        system.setUser("SAP-CRM-USER");
        system.setPassword("init1234");

        properties.setProperty("jco.client.ashost", system.getHost());
        properties.setProperty("jco.client.sysnr", system.getSystemNumber());
        properties.setProperty("jco.client.client", system.getClient());
        properties.setProperty("jco.client.user", system.getUser());
        properties.setProperty("jco.client.passwd", system.getPassword());
        properties.setProperty("jco.client.lang", system.getLanguage());
        System.out.println("******* Connection Parameter Set *******");
        MyDestinationDataProvider myProvider = new MyDestinationDataProvider();
        System.out.println("******* Destination Provider Set *******");
        myProvider.changePropertiesForABAP_AS(properties);
        if (!Environment.isDestinationDataProviderRegistered()) {
            System.out.println("Registering Destination Provider CRM");
            Environment.registerDestinationDataProvider((DestinationDataProvider) myProvider);
        }else{
            System.out.println("Destination Provider already set..CRM");
            connCRM_flag = false;
        }
        try {
            dest = JCoDestinationManager.getDestination((String) SAP_SERVER);
            repos = dest.getRepository();
            if (repos == null) {
                System.out.println("Repos is null.....");
            } else {
                System.out.println("Repos is not null.....");
            }
            System.out.println("After getting repos...");
            if(connCRM_flag){
               System.out.println("CRM Connection Successfull...");
            }
        } catch (Exception ex) {
            System.out.println(ex);
        }

        return dest;

    }

}

The JCo JavaDoc documentation says:

Only one implementation of DestinationDataProvider can be registered. For registering another implementation the infrastructure has first to unregister the implementation that is currently registered. It is not recommended to permanently exchange DestinationDataProvider registrations. The one registered instance should globally manage all destination configurations for the whole infrastructure environment.

So you have to register ONE instance of the DestinationDataProvider, this is an instance of your class MyDestinationDataProvider. This implementation needs to manage and store ALL the different logon configurations for all your SAP systems, accessible via a distinct destination name string. A simple HashMap<String, Properties> would be a sufficient storage form for this. Add the two Properties instances with distinct destination name strings to the HashMap and return the Properties instance associated to the passed destinationName from method MyDestinationDataProvider.getDestinationProperties(String destinationName). So you can access the desired JCoDestination instance targeting any SAP system via its specific destination name. In your example you used "SAP_SERVER" for both destination configurations which won't work. For example, use the SAP System ID (SID) as the destination name (key) instead.

If using the names from your example, then JCoDestinationManager.getDestination("CRM") would return the JCoDestination instance for system "CRM" and JCoDestinationManager.getDestination("R3") the JCoDestination for system "R3". And both can be used independently and simultaneously. That's it.