Calculate the difference between two dates in two days

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="16dp"
        android:background="#B3E5FC"
        tools:context=".MainActivity"
>
    <!--This example works only date picker mode = spinner mode only-->
    <!--DatePicker with spinner and without Calendar-->
    <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="set date 1"
            android:id="@+id/btnDate1" android:layout_alignParentTop="true" android:layout_alignParentLeft="true"
            android:layout_marginTop="42dp" android:onClick="setDate1"/>
    <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="set date 2"
            android:id="@+id/btnDate2" android:layout_alignTop="@+id/btnDate1" android:layout_alignParentRight="true"
            android:onClick="setDate2"/>
    <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="calculate"
            android:id="@+id/button"
            android:onClick="diff" android:layout_centerVertical="true" android:layout_centerHorizontal="true"
            android:textColor="#f21124"/>
    <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/editTextDate1" android:layout_below="@+id/btnDate1" android:layout_alignParentLeft="true"
            android:layout_alignRight="@+id/btnDate1"
            android:inputType="date" android:textColor="#9e0e1f" android:textSize="15dp"/>
    <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/editTextDate2" android:layout_below="@+id/btnDate2"
            android:layout_alignRight="@+id/btnDate2" android:layout_alignLeft="@+id/btnDate2"
            android:inputType="date" android:textColor="#e11515" android:textSize="15dp"/>
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceLarge"
            android:id="@+id/txtResult"
            android:text="............"
            android:textSize="14dp" android:layout_below="@+id/button" android:layout_alignLeft="@+id/num2"
            android:layout_alignStart="@+id/num2" android:textColor="#5c2e2e"/>
    <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:inputType="number"
            android:ems="10"
            android:id="@+id/num1" android:layout_below="@+id/editTextDate1" android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true"
            android:layout_toStartOf="@+id/button" android:layout_alignRight="@+id/editTextDate1"
            android:layout_alignEnd="@+id/editTextDate1" android:textColor="#590e9b" android:textSize="15dp"/>
    <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:inputType="number"
            android:ems="10"
            android:id="@+id/num2" android:layout_below="@+id/editTextDate2" android:layout_alignParentRight="true"
            android:layout_alignParentEnd="true" android:layout_alignLeft="@+id/editTextDate2"
            android:layout_alignStart="@+id/editTextDate2" android:textColor="#3818ad" android:textSize="15dp"/>
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="Між датами"
            android:id="@+id/textView"
            android:layout_alignBottom="@+id/txtResult" android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true" android:textColor="#060606" android:textSize="14dp"/>
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="Різниця між числами"
            android:id="@+id/textView2" android:layout_below="@+id/textView" android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true" android:textColor="#070707" android:textSize="14dp"/>
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="............"
            android:id="@+id/textDivNumber"
            android:layout_below="@+id/txtResult" android:layout_alignLeft="@+id/txtResult"
            android:layout_alignStart="@+id/txtResult" android:textColor="#782f2f" android:textSize="14dp"/>
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="Середнє значення"
            android:id="@+id/textView4" android:layout_below="@+id/textView2" android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true" android:textColor="#0a0a0a" android:textSize="14dp"/>
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="............"
            android:id="@+id/textAVG"
            android:layout_below="@+id/textDivNumber" android:layout_alignLeft="@+id/textDivNumber"
            android:layout_alignStart="@+id/textDivNumber" android:textColor="#7e3333" android:textSize="14dp"/>
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceSmall"
            android:text="Small Text"
            android:id="@+id/tv"
            android:layout_alignParentTop="true" android:layout_centerHorizontal="true"/>
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceSmall"
            android:text="днів"
            android:id="@+id/textView3"
            android:layout_above="@+id/textDivNumber" android:layout_alignParentRight="true"
            android:layout_alignParentEnd="true"/>
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceSmall"
            android:text="за день"
            android:id="@+id/textView5"
            android:layout_below="@+id/textDivNumber" android:layout_alignLeft="@+id/textView3"
            android:layout_alignStart="@+id/textView3" android:textSize="10dp" android:layout_alignParentRight="true"
            android:layout_alignParentEnd="true"/>
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="За місяць"
            android:id="@+id/textView6"
            android:textColor="#171414" android:textSize="14dp" android:layout_alignTop="@+id/txtZaMisiac"
            android:layout_alignParentLeft="true" android:layout_alignParentStart="true"/>
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="............"
            android:id="@+id/txtZaMisiac"
            android:layout_below="@+id/textView5" android:layout_alignLeft="@+id/textAVG"
            android:layout_alignStart="@+id/textAVG" android:textSize="14dp" android:textColor="#052df7"/>
</RelativeLayout>

DatePickerFragment

import android.app.DatePickerDialog;
import android.app.DialogFragment;
import android.os.Bundle;
import android.widget.EditText;
import android.widget.DatePicker;
import android.app.Dialog;
import java.util.Calendar;

public class DatePickerFragment extends DialogFragment implements DatePickerDialog.OnDateSetListener {

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState){

        final Calendar c = Calendar.getInstance();
        int year = c.get(Calendar.YEAR);
        int month = c.get(Calendar.MONTH);
        int day = c.get(Calendar.DAY_OF_MONTH);
        return new DatePickerDialog(getActivity(), this, year, month, day);
    }
    public void onDateSet (DatePicker view, int year, int month, int day) {
        EditText editTextDate1 = (EditText) getActivity().findViewById(R.id.editTextDate1);
        String stringOfDate = day + "." + (month+1) + "." + year;
        editTextDate1.setText(stringOfDate);
        }
    }

DatePickerFragment2

import android.app.DatePickerDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.os.Bundle;
import android.widget.DatePicker;
import android.widget.EditText;


import java.util.Calendar;

public class DatePickerFragment2 extends DialogFragment implements DatePickerDialog.OnDateSetListener {

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState){

        final Calendar c = Calendar.getInstance();
        int year = c.get(Calendar.YEAR);
        int month = c.get(Calendar.MONTH);
        int day = c.get(Calendar.DAY_OF_MONTH);
        return new DatePickerDialog(getActivity(), this, year, month, day);
    }

    public void onDateSet (DatePicker view, int year, int month, int day) {
        EditText editTextDate2 = (EditText) getActivity().findViewById(R.id.editTextDate2);
        String stringOfDate = day + "." + (month+1) + "." + year;
        editTextDate2.setText(stringOfDate);
    }
}

MainActivity

import android.app.DialogFragment;
import android.support.design.widget.TextInputLayout;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.format.DateFormat;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;


import java.text.DecimalFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.TimeUnit;

public class MainActivity extends AppCompatActivity {

    private EditText editTextDate1,editTextDate2,num1, num2;
    private TextView txtResult,tv, textDivNumber, textAVG, txtZaMisiac ;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        editTextDate1 = (EditText) findViewById(R.id.editTextDate1);
        editTextDate2 = (EditText) findViewById(R.id.editTextDate2);
        num1 = (EditText) findViewById(R.id.num1);
        num2 = (EditText) findViewById(R.id.num2);

        txtResult = (TextView) findViewById(R.id.txtResult);
        textDivNumber = (TextView) findViewById(R.id.textDivNumber);
        textAVG = (TextView) findViewById(R.id.textAVG);
        txtZaMisiac = (TextView) findViewById(R.id.txtZaMisiac);
        tv = (TextView) findViewById(R.id.tv);
        tv.setText("Current date "+(DateFormat.format("dd.MM.yyyy", new java.util.Date()).toString()));
        editTextDate1.setText(DateFormat.format("dd.MM.yyyy", new java.util.Date()).toString());
    }

    public void diff (View view) {
        SimpleDateFormat myFormat = new SimpleDateFormat("dd.MM.yyyy");
        String inputString1 = editTextDate1.getText().toString();
        String inputString2 = editTextDate2.getText().toString();
        String number11 = num1.getText().toString();
        String number12 = num2.getText().toString();

        String[] isbnParts = inputString1.split("\\.");
        if (Integer.parseInt(isbnParts[0])>31){
            Toast.makeText(this, "Схоже за все ви ввели забагато днів у місяці", Toast.LENGTH_SHORT).show();
        }
        if (Integer.parseInt(isbnParts[1])>12){
            Toast.makeText(this, "Гм...введено неіснуючий місяць)", Toast.LENGTH_SHORT).show();
        }

        String[] isbnParts1 = inputString2.split("\\.");
        if (Integer.parseInt(isbnParts1[0])>31){
            Toast.makeText(this, "Ей...тут введено забагато днів у місяці", Toast.LENGTH_SHORT).show();
        }
        if (Integer.parseInt(isbnParts1[1])>12){
            Toast.makeText(this, "Гм...ви ввели неіснуючий місяць)", Toast.LENGTH_SHORT).show();
        }

        if (inputString1.matches("")||inputString2.matches("")){
            Toast.makeText(this, "Не введено дат", Toast.LENGTH_SHORT).show();
        } else  {

            try {
                Date date1 = myFormat.parse(inputString1);
                Date date2 = myFormat.parse(inputString2);
                long diffDate = Math.abs(date2.getTime() - date1.getTime());
                txtResult.setText(""+ TimeUnit.DAYS.convert(diffDate, TimeUnit.MILLISECONDS));

            } catch (ParseException e) {
                e.printStackTrace();
            }
            if (number11.matches("")||number12.matches("")){Toast.makeText(this, "Не введено числа для розрахунку", Toast.LENGTH_SHORT).show();}
            else {

                String pattern = "##0.00";
                String pattern1 = "##0";
                DecimalFormat decimalFormat = new DecimalFormat(pattern);
                DecimalFormat decimalFormat1 = new DecimalFormat(pattern1);

                float number1 = Integer.parseInt(number11);
                float number2 = Integer.parseInt(number12);
                float diffDateInt =Integer.parseInt(txtResult.getText().toString());
                float diffnumb = Math.abs(number1 - number2);
                String format3 = decimalFormat1.format(diffnumb);
                textDivNumber.setText(String.valueOf(format3));
                String format = decimalFormat.format((diffnumb/diffDateInt)*30.00);
                txtZaMisiac.setText(String.valueOf(format));
                String format1 = decimalFormat.format(diffnumb/diffDateInt);
                textAVG.setText(String.valueOf(format1));                
            }
        }}

    public void setDate1 (View view) {
        DialogFragment newFragment = new DatePickerFragment();
        newFragment.show(getFragmentManager(),"Date Picker");
    }
    public void setDate2 (View view) {
        DialogFragment newFragment = new DatePickerFragment2();
        newFragment.show(getFragmentManager(),"Date Picker");
    }
}