范例HelloTimePicker

Android docs中的范例，简单翻译整理如下。
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1、创建新项目，名称HelloTimePicker；

2、修改res/layout/main.xml，内容如下：

<?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>

3、修改HelloTimePicker.java，增加成员变量定义，代码如下：

    private TextView mTimeDisplay;
    private Button mPickTime;

    private int mHour;
    private int mMinute;

    static final int TIME_DIALOG_ID = 0;

4、修改HelloTimePicker.java的onCreate方法，内容如下：

    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();
    }

5、修改HelloTimePicker.java增加updateDisplay和pad方法，内容如下：

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

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

6、修改HelloTimePicker.java增加时间选择对话框，内容如下：

    // 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();
            }
        };

7、修改HelloTimePicker.java增加onCreateDialog方法，内容如下：

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

8、运行项目，即可看到运行效果，如下图所示：