MainActivity.java

package com.darshanbshah.odsystem;

import android.app.DatePickerDialog;
import android.content.Intent;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.FrameLayout;
import android.widget.TextView;
import android.widget.Toast;

import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private FirebaseAuth mAuth;
    private TextView welcomeText;
    Calendar calendar = Calendar.getInstance();
    TextView from, to;
    FrameLayout frameLayout;
    EditText reason;
    String reasonString, fromDate, toDate, full;
    Boolean fullDay = false;

    FirebaseDatabase database = FirebaseDatabase.getInstance();
    DatabaseReference root;
    DatabaseReference student;
    DatabaseReference adv;
    DatabaseReference id;
    DatabaseReference roll_no;
    DatabaseReference email;
    DatabaseReference advisor;

    String recepient = "";

    List<String> list1 = new ArrayList<String>();


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mAuth = FirebaseAuth.getInstance();

        root = database.getReference();
        student = root.child("Student");
        adv = root.child("Advisors");
        id = student.child(mAuth.getCurrentUser().getUid());
        roll_no = id.child("RollNumber");
        email = id.child("Email");
        advisor = id.child("Advisor");


        welcomeText = (TextView)findViewById(R.id.welcomeText);
        welcomeText.setText("Welcome " + mAuth.getCurrentUser().getEmail());
        from = (TextView)findViewById(R.id.fromDateTV);
        to = (TextView)findViewById(R.id.toDateTV);