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Hello, Views >

# Hello, TimePicker

A `TimePicker` is a widget that allows the user to select the time by hour, minute and AM or PM.

1. Start a new project/Activity called HelloTimePicker.
2. Open the layout file and make it like so:

       <?xml version="1.0" encoding="utf-8"?>
       <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:orientation="vertical">

           <TextView android:id="@+id/timeDisplay"
               android:layout_width="wrap_content"
               android:layout_height="wrap_content"
               android:text=""/>

           <Button android:id="@+id/pickTime"
               android:layout_width="wrap_content"
               android:layout_height="wrap_content"
               android:text="Change the time"/>

       </LinearLayout>

   For the layout, we're using a vertical LinearLayout, with a `TextView` that will display the time and a `Button` that will initiate the `TimePicker` dialog. With this layout, the TextView will sit above the Button. The text value in the TextView is set empty, as it will be filled by our Activity with the current time.

3. Open HelloTimePicker.java. Insert the following to the HelloTimePicker class:

       private TextView mTimeDisplay;
       private Button mPickTime;

       private int mHour;
       private int mMinute;

       static final int TIME_DIALOG_ID = 0;

       @Override
       protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.main);

           // capture our View elements
           mTimeDisplay = (TextView) findViewById(R.id.timeDisplay);
           mPickTime = (Button) findViewById(R.id.pickTime);

           // add a click listener to the button
           mPickTime.setOnClickListener(new View.OnClickListener() {
               public void onClick(View v) {
                   showDialog(TIME_DIALOG_ID);
               }
           });

           // get the current time
           final Calendar c = Calendar.getInstance();
           mHour = c.get(Calendar.HOUR_OF_DAY);
           mMinute = c.get(Calendar.MINUTE);

           // display the current date
           updateDisplay();
       }

   Tip: Press Ctrl(or Cmd) + Shift + O to import all needed packages.

   We start by instantiating variables for our View elements and time fields. The `TIME_DIALOG_ID` is a static integer that uniquely identifies the dialog. In the `onCreate()` method, we get prepared by setting the layout and capturing the View elements. We then set an on-click listener for the Button, so that when it is clicked, it will show our TimePicker dialog. The `showDialog()` method will perform a callback to our Activity. (We'll define this callback in the next section.) We then create an instance of `Calendar` and get the current hour and minute. Finally, we call `updateDisplay()`—our own method that will fill the TextView with the time.

4. After the `onCreate()` method, add the `onCreateDialog()` callback method:

       @Override
       protected Dialog onCreateDialog(int id) {
           switch (id) {
           case TIME_DIALOG_ID:
               return new TimePickerDialog(this,
                       mTimeSetListener, mHour, mMinute, false);
           }
           return null;
       }

   This is passed the identifier we gave `showDialog()` and initializes the TimePicker to the time we retrieved from our Calendar instance. It will be called by `showDialog()`.

5. Now add our `updateDisplay()` method:

       // updates the time we display in the TextView
       private void updateDisplay() {
           mTimeDisplay.setText(
               new StringBuilder()
                       .append(pad(mHour)).append(":")
                       .append(pad(mMinute)));
       }

   This simply takes our member fields for the time and inserts them in the `mTimeDisplay` TextView. Note that we call a new method, `pad()`, on the hour and minute. (We'll create this method in the last step.)

6. Next, add a listener to be called when the time is reset:

       // the callback received when the user "sets" the time in the dialog
       private TimePickerDialog.OnTimeSetListener mTimeSetListener =
           new TimePickerDialog.OnTimeSetListener() {
               public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
                   mHour = hourOfDay;
                   mMinute = minute;
                   updateDisplay();
               }
           };

   Now when the user is done setting the time (clicks the "Set" button), we update our member fields with the new time and update our TextView.

7. Finally, add the `pad()` method that we called from the `updateDisplay()`:

       private static String pad(int c) {
           if (c >= 10)
               return String.valueOf(c);
           else
               return "0" + String.valueOf(c);
       }

   This method returns the appropriate String representation of the hour or minute. It will prefix a zero to the number if it's a single digit.

8. Now run it.

When you press the "Change the time" button, you should see the following:

### References

1. `TimePicker`
2. `Button`
3. `TextView`
4. `Calendar`

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