首先看一個簡單的練習。另寫一個名為TimePickerFragment的對話框fragment，允許用戶使用TimePicker組件選擇crime發生的具體時間。在CrimeFragment用戶界面上再添加一個按鈕，以顯示TimePickerFragment視圖界面。

跟書裏DatePicker的步驟很相似，大部分代碼相同，可以直接復制之前的改改就行，Date對象是包含日期和時間的，所以修改的時候只修改時間就可以了

1.首先創建布局文件dialog_time.xml

1 <TimePicker xmlns:android="http://schemas.android.com/apk/res/android"
 

2     android:id="@+id/dialog_time_picker"
3     android:layout_width="wrap_content"
4     android:layout_height="wrap_content"
5     android:calendarViewShown="false"
6     android:timePickerMode="spinner">
7 </TimePicker>

2.在fragment_crime.xml中原本的date按鈕後面添加一個按鈕，代碼跟date差不多，id換成crime_time

1 <Button
2         android:id="@+id/crime_time"
3         android:layout_width="match_parent"
4         android:layout_height="wrap_content" />

3.添加一個新的class名為TimePickerFragment

 1 package com.bignerdranch.android.criminalintent.fragment;
 2 
 3 import android.app.Activity;
 4
 
 import android.app.Dialog;
 5 import android.content.DialogInterface;
 6 import android.content.Intent;
 7 import android.os.Build;
 8 import android.os.Bundle;
 9 import android.support.v4.app.DialogFragment;
10 import android.support.v7.app.AlertDialog;
11 import android.view.LayoutInflater;
12 import android.view.View;
13 import android.widget.TimePicker;
14 
15 
16 import com.bignerdranch.android.criminalintent.R;
17 
18 import java.util.Calendar;
19 import java.util.Date;
20 import java.util.GregorianCalendar;
21 
22 public class TimePickerFragment extends DialogFragment {
23     //兩個按鈕共用一個EXTRA_DATE，所以不用新添加一個TimePicker專用的EXTRA_TIME
24     public static final String EXTRA_DATE = "com.bignerdranch.android.criminalintent.date";
25 
26     private static final String ARG_DATE = "date";
27 
28     private TimePicker mTimePicker;
29 
30     @Override
31     public Dialog onCreateDialog(Bundle savedInstanceState) {
32         Date date = (Date) getArguments().getSerializable(ARG_DATE);
33         final Calendar calendar = Calendar.getInstance();
34         calendar.setTime(date);
35         //一定得加final修飾年月日,不然GregorianCalendar的構造方法會報錯
36         final int year = calendar.get(Calendar.YEAR);
37         final int month = calendar.get(Calendar.MONTH);
38         final int day = calendar.get(Calendar.DAY_OF_MONTH);
39         //時分
40         int hour = calendar.get(Calendar.HOUR_OF_DAY);
41         int minute = calendar.get(Calendar.MINUTE);
42 
43         View v = LayoutInflater.from(getActivity()).inflate(R.layout.dialog_time, null);
44 
45         mTimePicker = (TimePicker) v.findViewById(R.id.dialog_time_picker);
46         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
47             mTimePicker.setHour(hour);
48             mTimePicker.setMinute(minute);
49         } else {
50             mTimePicker.setCurrentHour(hour);
51             mTimePicker.setCurrentMinute(minute);
52         }
53 
54         return new AlertDialog.Builder(getActivity())
55                 .setView(v)
56                 .setTitle(R.string.date_picker_title)
57                 .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
58                     @Override
59                     public void onClick(DialogInterface dialog, int which) {
60                         int hour, minute;
61                         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
62                             hour = mTimePicker.getHour();
63                             minute = mTimePicker.getMinute();
64                         } else {
65                             hour = mTimePicker.getCurrentHour();
66                             minute = mTimePicker.getCurrentMinute();
67                         }
68                         Date date = new GregorianCalendar(year, month, day, hour, minute).getTime();
69                         sendResult(Activity.RESULT_OK, date);
70                     }
71                 })
72                 .create();
73     }
74 
75     private void sendResult(int resultCode, Date date) {
76         if (getTargetFragment() == null) {
77             return;
78         }
79         Intent intent = new Intent();
80         intent.putExtra(EXTRA_DATE, date);
81         getTargetFragment().onActivityResult(getTargetRequestCode(), resultCode, intent);
82     }
83 
84     public static TimePickerFragment newInstance(Date date) {
85         Bundle args = new Bundle();
86         args.putSerializable(ARG_DATE, date);
87         TimePickerFragment fragment = new TimePickerFragment();
88         fragment.setArguments(args);
89         return fragment;
90     }
91 }

可以看到大部分代碼跟DatePickerFragment比較類似的，類似的代碼只不過把DatePicker換成了TimePicker而已，關於鍵值對不用修改，是因為兩個按鈕共用一個date，所以不用專門添加新的。不同點就是添加了時跟分的變量還有賦值處可以看到多了具體時間的賦值。

4.在CrimeFragment裏面添加全局變量Time按鈕、字符串變量DIALOG_TIME以及REQUEST_TIME判斷點擊的是哪個按鈕

1 private Button mTimeButton;
2 private static final String DIALOG_TIME = "DialogTime";
3 private static final int REQUEST_TIME = 0;

5.在CrimeFragment添加一個新的updateTime方法更新時間並在onCreateView裏面調用，順便控件綁定mTimeButton按鈕

1 private void updateTime() 
2 {
3         mTimeButton.setText(DateFormat.format("h:mm a", mCrime.getmDate()));
4 }

 1 mTimeButton = (Button)v.findViewById(R.id.crime_time);
 2         updateTime();
 3         mTimeButton.setOnClickListener(new View.OnClickListener() {
 4             @Override
 5             public void onClick(View v) {
 6                 FragmentManager manager = getFragmentManager();
 7                 TimePickerFragment dialog = TimePickerFragment.newInstance(mCrime.getmDate());
 8                 dialog.setTargetFragment(CrimeFragment.this, REQUEST_TIME);//設置目標Fragment，也就是前一個Fragment
 9                 dialog.show(manager,DIALOG_TIME);//第一個參數是FragmentManager，自動管理彈出的日歷對話框，第二個是TAG
10             }
11         });

6.修改CrimeFragment中的onActivityResult方法，因為在TimePickerFragment中回調了，要處理傳回來的結果

 1  @Override
 2     public void onActivityResult(int requestCode, int resultCode, Intent data) {
 3         if (resultCode != Activity.RESULT_OK) {
 4             return;
 5         }
 6         Date date = (Date) data.getSerializableExtra(DatePickerFragment.EXTRA_DATE);
 7         mCrime.setmDate(date);
 8         if (requestCode == REQUEST_DATE) {
 9             //因為TimePicker沒有年月日，所以不用專門使用updateTime更新TimePicker
10             updateDate();
11         }
12         if (requestCode == REQUEST_TIME) {
13             updateTime();
14             updateDate();
15         }
16     }

7.運行效果:

挑戰練習12.3 更多對話框