<?xml version="1.0" encoding="utf-8"?>

<LinearLayout 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"

    android:orientation="vertical"

    tools:context=".MainActivity">

    <Button

        android:id="@+id/button"

        android:layout_gravity="center"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="Button" />

    <CalendarView

        android:id="@+id/calendarView"

        android:layout_width="match_parent"

        android:layout_height="match_parent" />

</LinearLayout>

package com.lucky.test26calendar;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.CalendarView;

import android.widget.Toast;

import java.text.SimpleDateFormat;

public class MainActivity extends AppCompatActivity {

    CalendarView calendarView;

    Button button;

    String timeStr="";

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        calendarView=findViewById(R.id.calendarView);

        button=findViewById(R.id.button);

        //设置时间显示格式

        SimpleDateFormat simpleDateFormat=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  //yyyy表示年，MM表示月，dd表示天，HH表示时，mm表示分，ss表示秒

        timeStr=simpleDateFormat.format(calendarView.getDate()); //将calendarView获取的时间样式转化为simpleDateFormat所设置的样式

        button.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                Toast.makeText(MainActivity.this,timeStr,Toast.LENGTH_SHORT).show();

            }

        });

        calendarView.setOnDateChangeListener(new CalendarView.OnDateChangeListener() {

            @Override

            public void onSelectedDayChange( CalendarView view, int year, int month, int dayOfMonth) {

                timeStr=year+"-"+month+"-"+dayOfMonth;

            }

        });

    }

}