Picker(Time picker&& Date picker)

Android provides controls for the user to pick a time or pick a date as ready-to-use dialogs. Each picker provides controls for selecting each part of the time (hour, minute, AM/PM)
or date (month, day, year). Using these pickers helps ensure that your users can pick a time or date that is valid, formatted correctly, and adjusted to the user's locale.

We recommend that you use

DialogFragment

to
host each time or date picker. The

DialogFragment

manages
the dialog lifecycle for you and allows you to display the pickers in different layout configurations, such as in a basic dialog on handsets or as an embedded part of the layout on large screens.
推荐使用

DialogFragment

。
Although

DialogFragment

was
first added to the platform in Android 3.0 (API level 11), if your app supports versions of Android older than 3.0—even as low as Android 1.6—you can use the

DialogFragment

class
that's available in the support library for backward compatibility.

Note: The code samples below show how to create dialogs for a time picker and date picker using the support
library APIs for

DialogFragment

.
If your app's

minSdkVersion

is
11 or higher, you can instead use the platform version of

DialogFragment

.

Creating a Time Picker

To display a

TimePickerDialog

using

DialogFragment

,
you need to define a fragment class that extends

DialogFragment

and
return a

TimePickerDialog

from
the fragment's

onCreateDialog()

method.

Note: If your app supports versions of Android older than 3.0, be sure you've set up your Android project with the support library as described in Setting
Up a Project to Use a Library.

Extending DialogFragment for a time picker

To define a

DialogFragment

for
a

TimePickerDialog

,
you must:

Define the

onCreateDialog()

method
to return an instance of

TimePickerDialog

Implement the

TimePickerDialog.OnTimeSetListener

interface
to receive a callback when the user sets the time.

Here's an example:

public static class TimePickerFragment extends DialogFragment
                            implements TimePickerDialog.OnTimeSetListener {

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        // Use the current time as the default values for the picker
        final Calendar c = Calendar.getInstance();
        int hour = c.get(Calendar.HOUR_OF_DAY);
        int minute = c.get(Calendar.MINUTE);

        // Create a new instance of TimePickerDialog and return it
        return new TimePickerDialog(getActivity(), this, hour, minute,
                DateFormat.is24HourFormat(getActivity()));
    }

    public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
        // Do something with the time chosen by the user
    }
}

See the

TimePickerDialog

class
for information about the constructor arguments.
Now all you need is an event that adds an instance of this fragment to your activity.

Showing the time picker

Once you've defined a

DialogFragment

like
the one shown above, you can display the time picker by creating an instance of the

DialogFragment

and
calling

show()

.
For example, here's a button that, when clicked, calls a method to show the dialog:

<Button 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content"
    android:text="@string/pick_time" 
    android:onClick="showTimePickerDialog" />

When the user clicks this button, the system calls the following method:

public void showTimePickerDialog(View v) {
    DialogFragment newFragment = new TimePickerFragment();
    newFragment.show(getSupportFragmentManager(), "timePicker");
}

This method calls

show()

on
a new instance of the

DialogFragment

defined
above. The

show()

method
requires an instance of

FragmentManager

and
a unique tag name for the fragment.

需要注意的是：如果低于3.0，需要使用getSupportFragmentManager()来代替getFragmentManager()并且要继承FragmentActivity而不是Activity。
效果：



Caution: If your app supports versions of Android lower than 3.0, be sure that you call

getSupportFragmentManager()

to
acquire an instance of

FragmentManager

.
Also make sure that your activity that displays the time picker extends

FragmentActivity

instead
of the standard

Activity

class.

Creating a Date Picker

Creating a

DatePickerDialog

is
just like creating a

TimePickerDialog

.
The only difference is the dialog you create for the fragment.
To display a

DatePickerDialog

using

DialogFragment

,
you need to define a fragment class that extends

DialogFragment

and
return a

DatePickerDialog

from
the fragment's

onCreateDialog()

method.

Note: If your app supports versions of Android older than 3.0, be sure you've set up your Android project with the support library as described in Setting
Up a Project to Use a Library.

Extending DialogFragment for a date picker

To define a

DialogFragment

for
a

DatePickerDialog

,
you must:

Define the

onCreateDialog()

method
to return an instance of

DatePickerDialog

Implement the

DatePickerDialog.OnDateSetListener

interface
to receive a callback when the user sets the date.

Here's an example:

public static class DatePickerFragment extends DialogFragment
                            implements DatePickerDialog.OnDateSetListener {

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        // Use the current date as the default date in the picker
        final Calendar c = Calendar.getInstance();
        int year = c.get(Calendar.YEAR);
        int month = c.get(Calendar.MONTH);
        int day = c.get(Calendar.DAY_OF_MONTH);

        // Create a new instance of DatePickerDialog and return it
        return new DatePickerDialog(getActivity(), this, year, month, day);
    }

    public void onDateSet(DatePicker view, int year, int month, int day) {
        // Do something with the date chosen by the user
    }
}

See the

DatePickerDialog

class
for information about the constructor arguments.
Now all you need is an event that adds an instance of this fragment to your activity.

Showing the date picker

Once you've defined a

DialogFragment

like
the one shown above, you can display the date picker by creating an instance of the

DialogFragment

and
calling

show()

.
For example, here's a button that, when clicked, calls a method to show the dialog:

<Button 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content"
    android:text="@string/pick_date" 
    android:onClick="showDatePickerDialog" />

When the user clicks this button, the system calls the following method:

public void showDatePickerDialog(View v) {
    DialogFragment newFragment = new DatePickerFragment();
    newFragment.show(getSupportFragmentManager(), "datePicker");
}

This method calls

show()

on
a new instance of the

DialogFragment

defined
above. The

show()

method
requires an instance of

FragmentManager

and
a unique tag name for the fragment.
效果图：



Caution: If your app supports versions of Android lower than 3.0, be sure that you call

getSupportFragmentManager()

to
acquire an instance of

FragmentManager

.
Also make sure that your activity that displays the time picker extends

FragmentActivity

instead
of the standard

Activity

class.