DatePickerDialog

DatePickerDialog consente di selezionare una data, composta da giorno, mese e anno.
In questo esempio utilizzeremo un pulsante per visualizzare DatePicker e scegliere una data:

activity_main.xlm
<?xml version=”1.0″ encoding=”utf-8″?>
<LinearLayout
xmlns:android=”http://schemas.android.com/apk/res/android“
android:layout_width=”match_parent”
android:layout_height=”match_parent”
android:gravity=”center”
android:orientation=”vertical”>

<TextView
android:layout_width=”wrap_content”
android:layout_height=”wrap_content”
android:text=”Date Picker Dialog”/>
<DatePicker
        android:layout_width=”wrap_content”
android:layout_height=”wrap_content”
android:id=”@+id/datePicker”/>
   
<Button
android:layout_width=”wrap_content”
android:layout_height=”wrap_content”
android:text=”Click to choose a date”
android:id=”@+id/btn”/>
</LinearLayout>

MainActivity.java
package com.datePickerDialog.activities;

import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import com.datePickerDialog.R;
import android.widget.*;
import java.util.*;
import android.view.*;
import android.app.*;

public class MainActivity extends AppCompatActivity {
DatePicker datepicker;

Button btn;
int year,month,day;
static final int Dialog_Id=0;

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

datepicker=findViewById(R.id.datePicker);

Calendar calendar=Calendar.getInstance();
year=calendar.get(Calendar.YEAR);
month=calendar.get(Calendar.MONTH);
day=calendar.get(Calendar.DAY_OF_MONTH);
      
btn=findViewById(R.id.btn);
btn.setOnClickListener(new View.OnClickListener(){
public void onClick(View v){

showDialog(Dialog_Id);   
  
}
});
}

@Override
protected Dialog onCreateDialog(int id)
{
switch(id){
case Dialog_Id:
return new DatePickerDialog(
this,mDateSetListener,year,month,day);

}
return null;
}

private DatePickerDialog.OnDateSetListener mDateSetListener=
new DatePickerDialog.OnDateSetListener(){

public void onDateSet(DatePicker view,
  int mYear,int mMonth,int mDay){

Toast.makeText(getBaseContext(),
   “You have selected:”+(mMonth+1)
   +”-“+mDay
   +”-“+mYear,

   Toast.LENGTH_LONG).show();
}
};
}