questionare in android app by firebase

AfterFeedbackFragment.java

public class AfterFeedbackFragment extends Fragment {

    public AfterFeedbackFragment() {
        super();
    }

    public static AfterFeedbackFragment newInstance() {
        AfterFeedbackFragment fragment = new AfterFeedbackFragment();
        Bundle args = new Bundle();
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_afterfeedback, container, false);
        initInstances(rootView);
        return rootView;
    }

    public void initInstances(View rootView){

    }
}

FeedbackActivity.java

package com.mikkipastel.buslinebysukhum;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;

import com.mikkipastel.buslinebysukhum.fragment.AfterFeedbackFragment;
import com.mikkipastel.buslinebysukhum.fragment.FeedbackFragment;

/**
 * Created by acer on 9/4/2016.
 */
public class FeedbackActivity extends AppCompatActivity implements FeedbackFragment.FragmentListener{

    String userEmail;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_feedback);

        //get user email
        userEmail = getIntent().getStringExtra("user_email");

        if (savedInstanceState == null) {
            //1st created
            //place fragment
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.contentContainer, FeedbackFragment.newInstance(userEmail))
                    .commit();
        }
    }

    @Override
    public void onClick() {
        getSupportFragmentManager().beginTransaction()
                .remove(FeedbackFragment.newInstance(userEmail))
                .replace(R.id.contentContainer, AfterFeedbackFragment.newInstance())
                .commit();
    }
}

FeedbackFragment.java

package com.mikkipastel.buslinebysukhum.fragment;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.Toast;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.mikkipastel.buslinebysukhum.R;
import com.mikkipastel.buslinebysukhum.model.Message;

/**
 * Created by acer on 9/4/2016.
 */
public class FeedbackFragment extends Fragment {

    RadioGroup selectTopic;
    EditText inputTopic, inputDetail, inputEmail;
    Button submitData;

    String feedbackType, feedbackTopic, feedbackDetail;
    static String feedbackEmail;

    public FeedbackFragment() {
        super();
    }

    public static FeedbackFragment newInstance(String userEmail) {
        FeedbackFragment fragment = new FeedbackFragment();
        feedbackEmail = userEmail;
        Bundle args = new Bundle();
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_feedback, container, false);
        initInstances(rootView);
        return rootView;
    }

    public void initInstances(View rootView){
        selectTopic = (RadioGroup)rootView.findViewById(R.id.rgFeedback);
        inputTopic = (EditText)rootView.findViewById(R.id.inputTopic);
        inputDetail = (EditText)rootView.findViewById(R.id.inputDetail);
        inputEmail = (EditText)rootView.findViewById(R.id.inputEmail);

        submitData = (Button)rootView.findViewById(R.id.submit);
        submitData.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //get type of feedback topic
                switch (selectTopic.getCheckedRadioButtonId()){
                    case R.id.rbProblem: //rbProblem.isChecked()
                        feedbackType = "App problem";
                        break;
                    case R.id.rbBusline: //rbBusline.isChecked()
                        feedbackType = "Busline feedback";
                        break;
                    case R.id.rbFeedback: //rbFeedback.isChecked()
                        feedbackType = "User feedback";
                        break;
                    default:
                        feedbackType = "None";
                }

                //get topic and detail for feedback
                feedbackEmail = inputEmail.getText().toString();
                feedbackTopic = inputTopic.getText().toString();
                feedbackDetail = inputDetail.getText().toString();

                //check not null string and check length to quality feedback
                if (feedbackTopic.isEmpty()) {
                    Toast.makeText(getContext(),
                            "ใส่ชื่อหัวข้อให้ลุงด้วยนะจ๊ะ",
                            Toast.LENGTH_SHORT)
                            .show();
                } else if (feedbackDetail.isEmpty()) {
                    Toast.makeText(getContext(),
                            "ขอรายละเอียดด้วยจ้า",
                            Toast.LENGTH_SHORT)
                            .show();
                } else if (feedbackTopic.length() < 10) {
                    Toast.makeText(getContext(),
                            "ใส่ตัวอักษรที่ห้วข้อเพิ่มนิดนึงนะหลาน",
                            Toast.LENGTH_SHORT)
                            .show();
                } else if (feedbackDetail.length() < 15) {
                    Toast.makeText(getContext(),
                            "ลุงอยากได้รายละเอียดเพิ่ม เดี๋ยวทีมงานเขาดุลุงนะ",
                            Toast.LENGTH_SHORT)
                            .show();
                } else {
                    // Write a message to the database
                    FirebaseDatabase database = FirebaseDatabase.getInstance();
                    DatabaseReference rootDbRef = database.getReference(); //root

                    //point to sub-level in database
                    DatabaseReference feedbackDbRef = rootDbRef.child("user_feedback");
                    String tmp_stamp = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss", Locale.getDefault()).format(new Date());
                    Message userFeedback = new Message(feedbackType, feedbackTopic, feedbackDetail, tmp_stamp, feedbackEmail);
                    //rootDbRef.setValue(userFeedback);
                    feedbackDbRef.push().setValue(userFeedback);

                    //offline : Persistence Behavior
                    //FirebaseDatabase.getInstance().setPersistenceEnabled(true);

                    //send finish, Sukhum say thank you, pop to activity
                    FragmentListener listener = (FragmentListener) getActivity();
                    listener.onClick();
                }
            }
        });
    }

    //add for pop to activity
    public interface FragmentListener{
        void onClick();
    }


}

fragment_afterfeedback.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/transparent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:gravity="center_vertical">

    <ImageView
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:src="@drawable/sukhum"
        android:contentDescription="@string/app_sukhum"
        android:layout_gravity="center_horizontal"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:textSize="@dimen/fontsize_header"
        android:text="@string/sukhum_saythanks"
        android:id="@+id/textView"
        android:textColor="@color/white"
        android:layout_gravity="center_horizontal"
        android:fontFamily="font/TH Baijam.ttf"
        android:padding="@dimen/activity_vertical_margin" />

</LinearLayout>

fragment_feedback.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/transparent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin">

    <TextView
        android:id="@+id/header1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="@android:color/background_light"
        android:textSize="@dimen/fontsize_subheader"
        android:text="@string/feedback_header1" />

    <RadioGroup
        android:id="@+id/rgFeedback"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checkedButton="@+id/rbProblem"
        android:orientation="vertical">
        <RadioButton
            android:id="@+id/rbProblem"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="@android:color/background_light"
            android:textSize="@dimen/fontsize_normal"
            android:text="@string/feedback_detail1"/>
        <RadioButton
            android:id="@+id/rbBusline"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="@android:color/background_light"
            android:textSize="@dimen/fontsize_normal"
            android:text="@string/feedback_detail2"/>
        <RadioButton
            android:id="@+id/rbFeedback"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="@android:color/background_light"
            android:textSize="@dimen/fontsize_normal"
            android:text="@string/feedback_detail3"/>
    </RadioGroup>

    <android.support.design.widget.TextInputLayout
            android:id="@+id/input_layout_email"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
        <EditText
            android:id="@+id/inputEmail"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="textEmailAddress"
            android:hint="@string/feedback_header4"/>
    </android.support.design.widget.TextInputLayout>

    <android.support.design.widget.TextInputLayout
            android:id="@+id/input_layout_topic"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
        <EditText
            android:id="@+id/inputTopic"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="text"
            android:hint="@string/feedback_header2"/>
    </android.support.design.widget.TextInputLayout>

    <android.support.design.widget.TextInputLayout
            android:id="@+id/input_layout_detail"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
        <EditText
            android:id="@+id/inputDetail"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:maxLines="3"
            android:paddingBottom="@dimen/activity_padding_all"
            android:inputType="textMultiLine"
            android:hint="@string/feedback_header3"/>
    </android.support.design.widget.TextInputLayout>
    
    <Button
        android:id="@+id/submit"
        android:layout_marginTop="@dimen/activity_padding_all"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="@dimen/fontsize_normal"
        android:background="@color/blueA200"
        android:text="@string/feedback_submit"/>

</LinearLayout>