inversion_of_controll

EmailSender.java

package com.app.email;
public interface EmailSender {
    void send(String recipient, String message);
}

NotificationPolicy.java

package com.app.notifications;
import com.app.email.RealEmailSender;

public class NotificationsPolicy {
  private RealEmailSender emailSender = new RealEmailSender();
  public void fireNotification(){
        emailSender.send("john@gmail.com", "message");
    }
}

NotificationPolicy3.java

package com.app.notifications;
import com.app.email.EmailSender;
import com.app.email.RealEmailSender;
public class NotificationsPolicy {
    private EmailSender notificationSender;
    public NotificationsPolicy(EmailSender notificationSender) {
        this.notificationSender = notificationSender;
    }
    public void fireNotification() {
        notificationSender.send("john@gmail.com","message");
    }
}

NotificationsPolicy2.java

package com.app.notifications;
import com.app.email.EmailSender;
import com.app.email.RealEmailSender;
public class NotificationsPolicy {
    private EmailSender notificationSender = new RealEmailSender();
    public void fireNotification() {
        notificationSender.send("john@gmail.com","message");
    }
}

SmsAdapter.java

package com.app.adapter;
import com.app.notifications.NotificationGateway;
import com.app.sms.SmsSenderApi;
public class SmsAdapter implements NotificationGateway {
    private SmsSenderApi smsSenderApi;
    public SmsAdapter(SmsSenderApi smsSenderApi) {
        this.smsSenderApi = smsSenderApi;
    }
    @Override
    public void send(String recipient, String message) {
        smsSenderApi.sendSms(message, recipient);
    }
}