<?xml version="1.0" encoding="utf-8"?>
<relativelayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".datapickeractivity">

    <datepicker
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/datepicker"/>

</relativelayout>

package com.badao.relativelayouttest;

import androidx.appcompat.app.appcompatactivity;

import android.os.bundle;
import android.widget.datepicker;
import android.widget.toast;

import java.util.calendar;

public class datapickeractivity extends appcompatactivity {

    //用来存储年月日
    int year,month,day;
    //存储页面上的日期选择器
    datepicker datepicker;


    @override
    protected void oncreate(bundle savedinstancestate) {
        super.oncreate(savedinstancestate);
        setcontentview(r.layout.activity_data_picker);
        //获取页面上的日期选择器
        datepicker = (datepicker) findviewbyid(r.id.datepicker);
        //获取当前日期
        calendar calendar = calendar.getinstance();
        year = calendar.get(calendar.year);
        month = calendar.get(calendar.month);
        day = calendar.get(calendar.day_of_month);
        //初始化日期选择器并设置日期改变监听器
        datepicker.init(year, month, day, new datepicker.ondatechangedlistener() {
            @override
            public void ondatechanged(datepicker view, int year, int monthofyear, int dayofmonth) {
                //获取选中的年月日
                datapickeractivity.this.year = year;
                //月份是从0开始的
                datapickeractivity.this.month = (monthofyear+1);
                datapickeractivity.this.day = dayofmonth;
                //弹窗显示
                toast.maketext(datapickeractivity.this,datapickeractivity.this.year+"年"+datapickeractivity.this.month+"月"+datapickeractivity.this.day+"日",toast.length_short).show();
            }
        });

    }
}