How to calculate the number of days between two dates selected through date Picker in android

I want to calculate the number of days between the dates selected from date picker. Ive tried enough but couldn't find any solution! Please help me find the solution. This is the code for displaying datepicker when we click the editText. I have searched everywhere but couldn't find any proper results.

LeaveActivity.java

    public class LeaveActivity extends AppCompatActivity {

    private static EditText edt_tofrom;
    private static EditText edt_toDate;
    private TextView no_ofDays;

    private DatePickerDialog.OnDateSetListener edt_tofromlistener;
    private DatePickerDialog.OnDateSetListener edt_toDatelistener;


//    DatePickerDialogFragment mDatePickerDialogFragment;

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

        edt_tofrom = (EditText) findViewById(R.id.from_date);
        SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
//        edt_toform.setText( sdf.format(Calendar.getTime()));
        edt_toDate = (EditText) findViewById(R.id.to_date);
        no_ofDays = (TextView) findViewById(R.id.edt_noOfDays);
//        mDatePickerDialogFragment = new DatePickerDialogFragment();


//        edt_toform.setOnClickListener(this);
//        edt_toDate.setOnClickListener(this);

        edt_tofrom.setOnClickListener(new View.OnClickListener() {
            @RequiresApi(api = Build.VERSION_CODES.N)
            @Override
            public void onClick(View v) {
                Calendar calendar = Calendar.getInstance();
                int year = calendar.get(Calendar.YEAR);
                int month = calendar.get(Calendar.MONTH);
                int day = calendar.get(Calendar.DAY_OF_MONTH);
                int day1 = calendar.get(Calendar.DAY_OF_YEAR);

                DatePickerDialog datePickerDialog = new DatePickerDialog(LeaveActivity.this,
                        edt_tofromlistener, year, month, day);

                datePickerDialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.WHITE));
                datePickerDialog.show();
            }
        });

        edt_tofromlistener = new DatePickerDialog.OnDateSetListener() {
            @Override
            public void onDateSet(DatePicker view, int year, int month, int dayOfMonth){
                month = month + 1;
                Log.d("tag", "setDate: " + year + "/" + month + "/" + dayOfMonth + "");
                String date1 = +year + "/" + month + "/" + dayOfMonth + "";
                edt_tofrom.setText(date1);

            }
        };

        edt_toDate.setOnClickListener(new View.OnClickListener() {
            @RequiresApi(api = Build.VERSION_CODES.N)
            @Override
            public void onClick(View v) {
                Calendar calendar = Calendar.getInstance();
                int year = calendar.get(Calendar.YEAR);
                int month = calendar.get(Calendar.MONTH);
                int day = calendar.get(Calendar.DAY_OF_MONTH);
                int day2 = calendar.get(Calendar.DAY_OF_YEAR);

                DatePickerDialog datePickerDialog = new DatePickerDialog(LeaveActivity.this,
                        edt_toDatelistener, year, month, day);

                datePickerDialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.WHITE));
                datePickerDialog.show();


            }
        });

        edt_toDatelistener = new DatePickerDialog.OnDateSetListener() {
            @Override
            public void onDateSet(DatePicker view, int year, int month, int dayOfMonth) {
                month = month + 1;
                Log.d("tag", "setDate: " + year + "/" + month + "/" + dayOfMonth + "");

                String date2 = +year + "/" + month + "/" + dayOfMonth + "";
                edt_toDate.setText(date2);

            }

        };

    }


}

activity_leave.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    android:padding="10dp"

    tools:context=".activities.LeaveActivity">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="APPLY FOR LEAVE"
            android:textSize="24sp"
            android:layout_gravity="center"
            android:textStyle="bold"
            android:background="@drawable/editt_text_background"/>

    </LinearLayout>


    <!-- TODO: Update blank fragment layout -->


    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:background="@drawable/editt_text_background">
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="10dp"
                android:orientation="horizontal"
                android:layout_weight="1">

                <TextView
                    android:id="@+id/selectTxtView"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginStart="10dp"
                    android:layout_marginTop="10dp"
                    android:layout_marginEnd="10dp"
                    android:layout_marginBottom="10dp"
                    android:padding="10dp"
                    android:text="Select Leave Type"
                    android:textSize="15sp"
                    android:textStyle="bold"/>

                <Spinner
                    android:id="@+id/spinner"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_margin="10dp"
                    android:layout_toEndOf="@id/selectTxtView"
                    android:background="@drawable/editt_text_background"
                    android:entries="@array/LeaveType"
                    android:padding="10dp" />
            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="5dp"
                android:orientation="horizontal"
                android:padding="10dp"
                android:layout_weight="1">

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="From Date:"
                    android:textColor="#000000"/>

                <EditText
                    android:id="@+id/from_date"
                    android:layout_width="0dp"
                    android:layout_height="wrap_content"
                    android:ems="10"
                    android:layout_weight="1"
                    android:background="@drawable/editt_text_background"
                    android:clickable="true"
                    android:longClickable="false"
                    android:inputType="date"
                    android:layout_marginStart="36dp"
                    android:layout_marginEnd="20dp"
                    android:focusable="false"/>



                <!--            <DatePicker-->
                <!--                android:id="@+id/date_picker"-->
                <!--                android:layout_width="wrap_content"-->
                <!--                android:layout_height="wrap_content"-->
                <!--                android:calendarViewShown="false"-->
                <!--                android:datePickerMode="spinner"/>-->

            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal"
                android:padding="10dp">

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_margin="5dp"
                    android:text="To Date:"
                    android:textColor="#000000"/>

                <EditText
                    android:id="@+id/to_date"
                    android:layout_width="0dp"
                    android:layout_height="wrap_content"
                    android:layout_weight="1"
                    android:ems="10"
                    android:background="@drawable/editt_text_background"
                    android:clickable="true"
                    android:longClickable="false"
                    android:inputType="date"
                    android:layout_marginStart="36dp"
                    android:layout_marginEnd="20dp"
                    android:focusable="false" />
            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:padding="10dp"
                android:layout_weight="1">
                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="No.Of Days:"
                    android:textColor="#000"
                    android:padding="10dp"/>
                <TextView
                    android:id="@+id/edt_noOfDays"
                    android:layout_width="0dp"
                    android:layout_height="wrap_content"
                    android:layout_weight="1"
                    android:background="@drawable/editt_text_background"/>
            </LinearLayout>

      </ScrollView>

 </LinearLayout>

Use following function to count diference of days between two Date, you can also use same for calculating difrence of Hours, Minutes or Seconds by just change the return object.

public static Long getDateDifferenceInDays(Date startDate, Date endDate) {

    Long different = endDate.getTime() - startDate.getTime();

    Long secondsInMilli = 1000L;
    Long minutesInMilli = secondsInMilli * 60;
    Long hoursInMilli = minutesInMilli * 60;
    Long daysInMilli = hoursInMilli * 24;

    Long elapsedDays = different / daysInMilli;
    different = different % daysInMilli;

    Long elapsedHours = different / hoursInMilli;
    different = different % hoursInMilli;

    Long elapsedMinutes = different / minutesInMilli;
    different = different % minutesInMilli;

    Long elapsedSeconds = different / secondsInMilli;

    System.out.printf("%d days, %d hours, %d minutes, %d seconds%n", elapsedDays, elapsedHours, elapsedMinutes, elapsedSeconds);

    return elapsedDays;
}

Never use Calendar. It was years ago supplanted by the modern java.time classes defined in JSR 310.

For date values without time of day and without time zone, use LocalDate.

I do not know Android. But you seem to be getting the year, month, and day as integers from your picker. Make LocalDate objects of those.

LocalDate localDate = LocalDate.of( y , m , d ) ;

Calculate elapsed days.

long days = ChronoUnit.DAYS.between( start , end ) ;

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes. Hibernate 5 & JPA 2.2 support java.time.

Where to obtain the java.time classes?

• Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
• Java 9 adds some minor features and fixes.
• Java SE 6 and Java SE 7
• Most of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
• Android
• Later versions of Android bundle implementations of the java.time classes.
• For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….