Question

I am new to android word.

I am doing a text view spinner with time and date picker.

1. How to set current time and date in the text view by default.
2. After select time/date and click “set” button, why my time/date selection is empty

here is my activity_main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:paddingLeft="16dp"
android:paddingRight="16dp"
android:orientation="vertical" >

<TextView
    android:id="@+id/startTime"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"                 
    style="@android:style/Widget.Holo.Spinner" 
    android:onClick="showTimePickerDialog"/>
<TextView
    android:id="@+id/endTime"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"                 
    style="@android:style/Widget.Holo.Spinner" 
    android:onClick="showTimePickerDialog"/>
<TextView
    android:id="@+id/date"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"                 
    style="@android:style/Widget.Holo.Spinner" 
    android:onClick="showDatePickerDialog"/>

here is my MainActivity.java

import java.util.Calendar;
import android.os.Bundle;
import android.app.Activity;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.app.TimePickerDialog;
import android.text.format.DateFormat;
import android.view.Menu;
import android.view.View;
import android.widget.DatePicker;
import android.widget.TimePicker;

public class MainActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    public void showTimePickerDialog(View v) {
        DialogFragment newFragment = new TimePickerFragment();
        newFragment.show(getFragmentManager(), "timePicker");
    }

    public void showDatePickerDialog(View v) {
        DialogFragment newFragment = new DatePickerFragment();
        newFragment.show(getFragmentManager(), "datePicker");
    }

    public static class TimePickerFragment extends DialogFragment implements TimePickerDialog.OnTimeSetListener {

        @Override
        public Dialog onCreateDialog(Bundle savedInstanceState) {
            // Use the current time as the default values for the picker
            final Calendar c = Calendar.getInstance();
            int hour = c.get(Calendar.HOUR_OF_DAY);
            int minute = c.get(Calendar.MINUTE);

            // Create a new instance of TimePickerDialog and return it
            return new TimePickerDialog(getActivity(), this, hour, minute,
                    DateFormat.is24HourFormat(getActivity()));
        }

        public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
            // Do something with the time chosen by the user
        }
    }

    public static class DatePickerFragment extends DialogFragment implements DatePickerDialog.OnDateSetListener {

        @Override
        public Dialog onCreateDialog(Bundle savedInstanceState) {
            // Use the current date as the default date in the picker
            final Calendar c = Calendar.getInstance();
            int year = c.get(Calendar.YEAR);
            int month = c.get(Calendar.MONTH);
            int day = c.get(Calendar.DAY_OF_MONTH);

            // Create a new instance of DatePickerDialog and return it
            return new DatePickerDialog(getActivity(), this, year, month, day);
        }

        public void onDateSet(DatePicker view, int year, int month, int day) {
            // Do something with the date chosen by the user
        }
    }
}

Thank you.

Answer 1

The problem I see is that your DatePickerFragment and TimePickerFragments are static, so they cannot access your activity’s textviews. If they were not static, then all you’ll need to do is timeTextView.setText(...) inside of onTimeSet(...) method. (By the way, keeping them static is good because you can reuse in another activity if you need to.)

One way to get around this would be to create an extra interface and then pass that to your picker dialog fragments when you create them and then make a callback. But why do that when OnDateSetListener and OnTimeSetListener interfaces already exist?

I am going to refer only to the DatePickerFragment below, but all the same applies to the TimePickerFragment as well.

Your MainActivity should implement OnDateSetListener, not your DatePickerFragment. One of the overriden methods from OnDateSetListener is onDateSet(...) where you set the date in your TextView. For example:

@Override
public void onDateSet(DatePicker view, int year, int monthOfYear,
        int dayOfMonth) {
    Calendar cal = new GregorianCalendar(year, monthOfYear, dayOfMonth);
    mDateTextView.setText(DATE_FORMATTER.format(cal.getTime()));
}

Your DatePickerFragment should have a constructor which takes an OnDateSetListener as a parameter and holds a reference to it. See how to implement your DatePickerFragment here https://gist.github.com/2935353

Now inside your showDatePickerDialog(View v), pass your MainActivity (which is also an OnDateSetListener) like this:

FragmentTransaction ft = getFragmentManager().beginTransaction();
DialogFragment newFragment = new DatePickerDialogFragment(MainActivity.this);
newFragment.show(ft, "date_dialog");

Then when the time is set, your MainActivity which implements ‘OnDateSetListener’ will get a callback and your textview will be updated.

Hope this clears things up a bit.

P.S. You should also have empty constructor in the DatePickerFragment, it will prevent your app from crashing when the device is rotated.