Calendar ca = Calendar.getInstance();mYear = ca.get(Calendar.YEAR);mMonth = ca.get(Calendar.MONTH);mDay = ca.get(Calendar.DAY_OF_MONTH);

btn_day.setOnClickListener(new View.OnClickListener() {  @Override  public void onClick(View v) {    //TODO 調用時間選擇器    new DatePickerDialog(MainActivity.this, onDateSetListener, mYear, mMonth, mDay).show();  }});

/** * 日期選擇器對話框監聽 */private DatePickerDialog.OnDateSetListener onDateSetListener = new DatePickerDialog.OnDateSetListener() {  @Override  public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {    mYear = year;    mMonth = monthOfYear;    mDay = dayOfMonth;    String days;    if (mMonth + 1 < 10) {      if (mDay < 10) {        days = new StringBuffer().append(mYear).append("年").append("0").            append(mMonth + 1).append("月").append("0").append(mDay).append("日").toString();      } else {        days = new StringBuffer().append(mYear).append("年").append("0").            append(mMonth + 1).append("月").append(mDay).append("日").toString();      }    } else {      if (mDay < 10) {        days = new StringBuffer().append(mYear).append("年").            append(mMonth + 1).append("月").append("0").append(mDay).append("日").toString();      } else {        days = new StringBuffer().append(mYear).append("年").            append(mMonth + 1).append("月").append(mDay).append("日").toString();      }    }    tv_data.setText(days);  }};