How to create Spinner to show current and next 30 dates

问题

How can I create a date Spinner, which shows current date in EditText as default and future dates in Spinner (like, for next 30 days)

I used date picker in many apps, so I am familiar with date picker dialog but don't have any idea about date spinner.

Note
Please don't tell me How to style EditText as Spinner

EDITED: 1 AS RECOMMENDED BY @erakitin

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

    Spinner spinnerDateIn = (Spinner) findViewById(R.id.spinnerDateIn);
    Spinner spinnerDateOut = (Spinner) findViewById(R.id.spinnerDateOut);       

    spinnerDateIn.setAdapter(new CalendarSpinnerAdapter(SpinnerDateActivity.this, 30));         

}

EDITED: 2 AS RECOMMENDED BY @erakitin in new update

CalendarSpinnerAdapter mSpinnerDateInAdapter = new CalendarSpinnerAdapter(SpinnerDateActivity.this, 30);
        spinnerDate.setAdapter(mSpinnerDateInAdapter);

        spinnerDate.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                spinnerDate.setSelection(position);
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });

Now, trying to get value of selected Item in String but getting: java.util.GregorianCalendar, where i am doing mistake ?

strDate = spinnerDate.getSelectedItem().toString();

回答1:

There are a simple example of adapter for Spinner below.

public class CalendarSpinnerAdapter extends BaseAdapter {

    private SimpleDateFormat mDateFormat = new SimpleDateFormat("d MMM yyyy");

    private LayoutInflater mInflater;
    private Calendar mCalendar;
    private int mDayCount;
    private int mLastRequestedDay = 0;

    public CalendarSpinnerAdapter(Context context, int dayCount) {
        mInflater = LayoutInflater.from(context);
        mDayCount = dayCount;
        mCalendar = Calendar.getInstance();
    }

    @Override
    public int getCount() {
        return mDayCount;
    }

    @Override
    public Calendar getItem(int position) {
        mCalendar.add(Calendar.DAY_OF_YEAR, position - mLastRequestedDay);
        mLastRequestedDay = position;
        return mCalendar;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (convertView == null) {
            convertView = mInflater.inflate(android.R.layout.simple_spinner_dropdown_item, parent, false);
        }

        Calendar item = getItem(position);
        ((TextView) convertView).setText(mDateFormat.format(item.getTimeInMillis()));

        return convertView;
    }

    @Override
    public View getDropDownView(int position, View convertView, ViewGroup parent) {
        return getView(position, convertView, parent);
    }
}

How to use it for display current date and next 29 days:

mDateSpinner.setAdapter(new CalendarSpinnerAdapter(getActivity(), 30));

UPD:

We should add a parameter to adapter's constructor for setting the starting date:

public CalendarSpinnerAdapter(Context context, Calendar startDate, int dayCount) {
    mInflater = LayoutInflater.from(context);
    mDayCount = dayCount;
    mCalendar = Calendar.getInstance();
    mCalendar.setTimeInMillis(startDate.getTimeInMillis());
}

Then add listener for spinnerDateIn where we can initialize the second spinner:

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

    Spinner spinnerDateIn = (Spinner) findViewById(R.id.spinnerDateIn);
    final Spinner spinnerDateOut = (Spinner) findViewById(R.id.spinnerDateOut);

    mSpinnerDateInAdapter = new CalendarSpinnerAdapter(SpinnerDateActivity.this, Calendar.getInstance(), 30);
    spinnerDateIn.setAdapter(mSpinnerDateInAdapter);

    spinnerDateIn.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            Calendar dateIn = Calendar.getInstance();
            dateIn.setTimeInMillis(mSpinnerDateInAdapter.getItem(position).getTimeInMillis());
            dateIn.add(Calendar.DAY_OF_YEAR, 1); // add one day
            mSpinnerDateOutAdapter = new CalendarSpinnerAdapter(SpinnerDateActivity.this, dateIn, 30);
            spinnerDateOut.setAdapter(mSpinnerDateOutAdapter);
        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {

        }
    });
}

I didn't try this code but it should work.

UPD2:

spinnerDate.setSelection(position) returns Calendar class instance. If you want to get selected date as String you should format it. Try to use following method:

private String getSelectedDateAsString(Spinner dateSpinner) {
    Calendar selectedDate = (Calendar) dateSpinner.getSelectedItem();
    return new SimpleDateFormat("d MMM yyyy").format(selectedDate.getTimeInMillis());
}

回答2:

Spinner works with an Adapter. If you want to show in your spinner the date from today up to the end of the month you can do. Let's create a model class, with one can use to feed the Adapter,

  public class MyDateInterval {
    public String mDateString;
    public Date mDate;

    public MyDateInterval(String dateString, Date date) {
        mDateString = dateString;
        mDate = date;
    }

    @Override
    public String toString() {
        return mDateString;
    }
}

Now we define an ArrayList<MyDateInterval>, that we will fill up with the date you want to show:

ArrayList<MyDateInterval> items = new ArrayList<>();

Retrieve the end date on the format of your example:

SimpleDateFormat dateFormat = new SimpleDateFormat("dd MMM yyyy");
Calendar c = Calendar.getInstance();
c.set(Calendar.MONTH, 6);
c.set(Calendar.DAY_OF_MONTH, c.getActualMaximum(Calendar.DAY_OF_MONTH));
// for the sake of the example 31 Jul 2015
Date endDate = c.getTime();
Log.e(getClass().getSimpleName(), dateFormat.format(endDate));

Now we calculated the interval from today up to the end date

Calendar todayCalendar = Calendar.getInstance();
while(endDate.after(todayCalendar.getTime())) {
    items.add(new MyDateInterval(dateFormat.format(todayCalendar.getTime()), todayCalendar.getTime());
    todayCalendar.add(Calendar.DAY_OF_MONTH, 1);
 }

Now we all the pieces. You have to create the Adapter for the Spinner.

ArrayAdapter<MyDateInterval> dataAdapter = new ArrayAdapter<>(this,
                            android.R.layout.simple_spinner_item, items);
dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(dataAdapter);

and that should be all.

来源：https://stackoverflow.com/questions/21526982/how-to-create-spinner-to-show-current-and-next-30-dates