旺仔：日期选择控件

package com.example.administrator.mytest;

import android.annotation.TargetApi;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.icu.util.Calendar;
import android.os.Build;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
private int myear,mmonth,mday;
    Button bt_1;
    TextView dateDisplay;
    static final int Date_Dialog_Id=0;
    //日期被设置时候触发监听器
    private DatePickerDialog.OnDateSetListener os1=new DatePickerDialog.OnDateSetListener() {
        @Override
        public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
            myear=year;
            mmonth=monthOfYear;
            mday=dayOfMonth;
            dateDisplay.setText(myear+"-"+mmonth+"-"+mday);
        }
    };

    //创建一个新的窗口然后返回
    @Override
    protected Dialog onCreateDialog(int id) {
        switch (id)
        {
            case Date_Dialog_Id:
                return new DatePickerDialog(this,os1,myear,mmonth,mday);
        }
        return null;
    }

    @TargetApi(Build.VERSION_CODES.N)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final Calendar c=Calendar.getInstance();
        myear=c.get(Calendar.DAY_OF_YEAR);
        mmonth=c.get(Calendar.MONTH);
        mday=c.get(Calendar.DAY_OF_MONTH);
     dateDisplay=(TextView)findViewById(R.id.tv_1);
        bt_1=(Button)findViewById(R.id.bt_1);
        bt_1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //重写其内部方法来显示窗口
                showDialog(Date_Dialog_Id);
            }
        });

    }

}

<?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"
    tools:context="com.example.administrator.mytest.MainActivity"
    android:orientation="vertical">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tv_1"
        android:layout_marginTop="20dp"
        android:text="请设置日期" />
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="请设置时间"
        android:layout_marginTop="50dp"
        android:id="@+id/bt_1"/>
</LinearLayout>