日歷選擇器上默認的時間不是手機系統的時間， 是隨機的一個時間，是正常的嗎？看老師的是手機默認時間啊

代碼：

package com.example.hys.datatimepick;

import android.app.DatePickerDialog;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.DatePicker;
import android.widget.TimePicker;

import java.util.Calendar;

public class MainActivity extends AppCompatActivity {

? ?private TimePicker tp;
? ?private DatePicker dp;
? ?private Calendar cal;
? ?private int year;
? ?private int month;
? ?private int day;
? ?private int hour;
? ?private int minute;
? ?private int second;

? ?@Override
? ?protected void onCreate(Bundle savedInstanceState) {
? ? ? ?super.onCreate(savedInstanceState);
? ? ? ?setContentView(R.layout.activity_main);
? ? ? ?//獲取日歷的對像
? ? ? ?cal = Calendar.getInstance();
? ? ? ?//獲取時間
? ? ? ?year = cal.get(Calendar.YEAR);
? ? ? ?month = cal.get(Calendar.MONTH)+1;
? ? ? ?day = cal.get(Calendar.DAY_OF_MONTH);
? ? ? ?hour = cal.get(Calendar.HOUR_OF_DAY);
? ? ? ?minute = cal.get(Calendar.MINUTE);
? ? ? ?second = cal.get(Calendar.SECOND);
? ? ? ?setTitle(year+"-"+month+"-"+day+" "+hour+":"+minute+":"+second);
? ? ? ?dp = (DatePicker) findViewById(R.id.datePicker);
? ? ? ?tp = (TimePicker) findViewById(R.id.timePicker);
? ? ? ?//初始化datepicker
? ? ? ?dp.init(year, cal.get(Calendar.MINUTE), day, new DatePicker.OnDateChangedListener() {
? ? ? ? ? ?@Override
? ? ? ? ? ?public void onDateChanged(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
? ? ? ? ? ? ? ?setTitle(year+"-"+(monthOfYear+1)+"-"+dayOfMonth);
? ? ? ? ? ?}
? ? ? ?});
? ? ? ?tp.setOnTimeChangedListener(new TimePicker.OnTimeChangedListener() {
? ? ? ? ? ?@Override
? ? ? ? ? ?public void onTimeChanged(TimePicker view, int hourOfDay, int minute) {
? ? ? ? ? ? ? ?setTitle(hourOfDay+":"+minute);
? ? ? ? ? ?}
? ? ? ?});


? ? ? ?new DatePickerDialog(this, new DatePickerDialog.OnDateSetListener() {
? ? ? ? ? ?@Override
? ? ? ? ? ?public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
? ? ? ? ? ? ? ?setTitle(year+"-"+(monthOfYear+1)+"-"+dayOfMonth);
? ? ? ? ? ?}
? ? ? ?},year, cal.get(Calendar.MINUTE),day).show();


? ?}
}