時間日期選擇器、對話框

public class MainActivity extends ActionBarActivity {
    private Context mContext;

    private TimePicker timePicker;
    private DatePicker datePicker;

    private Button btn_date;
    private Button btn_time;

    private int year;
    private int month;
    private int day;
    private int hour;
    private int minute;
    private int second;

    private String date;
    private String time;

    private Formatter fmt;
    private Calendar cal;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mContext = this;

        cal = Calendar.getInstance();
        year = cal.get(Calendar.YEAR);
        month = cal.get(Calendar.MONTH);
        day = cal.get(Calendar.DAY_OF_MONTH);
        hour = cal.get(Calendar.HOUR_OF_DAY);
        minute = cal.get(Calendar.MINUTE);
        second = cal.get(Calendar.SECOND);

        fmt = new Formatter();
        fmt.format("%d/%d/%d",year,month,day);
        date = fmt.toString();
        fmt = new Formatter();
        fmt.format("%d:%d:%d", hour, minute, second);
        time = fmt.toString();


        changeDate();

        datePicker = (DatePicker)findViewById(R.id.datePicker);
        timePicker = (TimePicker)findViewById(R.id.timePicker);

        datePicker.init(year, month, day, new DatePicker.OnDateChangedListener() {
            @Override
            public void onDateChanged(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
                fmt = new Formatter();
                fmt.format("%d/%d/%d",year,(monthOfYear+1),dayOfMonth); //month從0開始 所以需要加1
                date = fmt.toString();
                changeDate();
            }
        });

        timePicker.setOnTimeChangedListener(new TimePicker.OnTimeChangedListener() {
            @Override
            public void onTimeChanged(TimePicker view, int hourOfDay, int minute) {
                fmt = new Formatter();
                fmt.format("%d:%d",hourOfDay,minute);
                time = fmt.toString();
                changeDate();
            }
        });




        //時間 日期 對話框

        btn_date = (Button)findViewById(R.id.btn_date);
        btn_time = (Button)findViewById(R.id.btn_time);

        //日期選擇器
        btn_date.setOnClickListener(new Button.OnClickListener() {
            @Override
            public void onClick(View v) {
                new DatePickerDialog(mContext, new DatePickerDialog.OnDateSetListener() {
                    @Override
                    public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
                        fmt = new Formatter();
                        fmt.format("%d/%d/%d",year,(monthOfYear+1),dayOfMonth); //month從0開始 所以需要加1
                        date = fmt.toString();
                        changeDate();
                    }
                },cal.get(Calendar.YEAR),cal.get(Calendar.MONTH),cal.get(Calendar.DAY_OF_MONTH)).show();
            }
        });

        //時間選擇器
        btn_time.setOnClickListener(new Button.OnClickListener() {
            @Override
            public void onClick(View v) {
                new TimePickerDialog(mContext, new TimePickerDialog.OnTimeSetListener() {
                    @Override
                    public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
                        fmt = new Formatter();
                        fmt.format("%d:%d",hourOfDay,minute);
                        time = fmt.toString();
                        changeDate();
                    }
                },cal.get(Calendar.HOUR_OF_DAY),cal.get(Calendar.MINUTE),true).show();
            }
        });
    }

    private void changeDate(){
        setTitle(date + " "  +time);
    }
}