Android Simple Calendar

Alot of people have been annoyed with the lack of a simple native calendar on Android…and rightfully so! Having to sync personal calendar events with Google’s online calendar may not be everyone’s frenzy. Some personal calendar events …are just that ..personal…mmh!

I am aware of AnCal by Piotr Zagawa and the new Calendar contained in OpenIntents by Karl Ostmo. There are also the calendar widgets which decorate the phonetop. Clearly, these guys should be appreciated in terms of their effort in coming up with a native Android Calendar.

In this tutorial, I would like to provide a quick skeleton framework for creating your own native Android Calendar. Feel free to improve, customize and hack at mine!

Download: SimpleCalendarImp.zip

Features:
- Contains slots to show number of events per day

File: simple_calendar_view.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
	xmlns:android="http://schemas.android.com/apk/res/android"
	android:orientation="vertical"
	android:layout_width="fill_parent"
	android:layout_height="fill_parent"
	android:background="@drawable/bg">

	<ImageView
		android:id="@+id/calendarToJournalButton"
		android:src="@drawable/add_entry_button_selector"
		android:gravity="left"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		android:paddingBottom="10dip">
	</ImageView>


	<Button
		android:id="@+id/selectedDayMonthYear"
		android:textColor="#FFFFFF"
		android:layout_gravity="center"
		android:textAppearance="?android:attr/textAppearanceMedium"
		android:background="@drawable/calendar_top_header"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content">
	</Button>

	<LinearLayout
		xmlns:android="http://schemas.android.com/apk/res/android"
		android:orientation="horizontal"
		android:layout_width="fill_parent"
		android:layout_height="wrap_content">

		<ImageView
			android:id="@+id/prevMonth"
			android:src="@drawable/calendar_left_arrow_selector"
			android:layout_width="wrap_content"
			android:layout_height="wrap_content">
		</ImageView>
		<Button
			android:id="@+id/currentMonth"
			android:layout_weight="0.6"
			android:textColor="#FFFFFF"
			android:textAppearance="?android:attr/textAppearanceMedium"
			android:background="@drawable/calendar_bar"
			android:layout_width="wrap_content"
			android:layout_height="wrap_content">
		</Button>
		<ImageView
			android:id="@+id/nextMonth"
			android:src="@drawable/calendar_right_arrow_selector"
			android:layout_width="wrap_content"
			android:layout_height="wrap_content">
		</ImageView>
	</LinearLayout>

	<LinearLayout
		android:layout_gravity="center"
		android:layout_width="fill_parent"
		android:layout_height="wrap_content">
		<ImageView
			android:id="@+id/calendarheader"
			android:src="@drawable/blue_bg_with_text"
			android:layout_gravity="center"
			android:layout_width="fill_parent"
			android:layout_height="wrap_content">
		</ImageView>
	</LinearLayout>


	<GridView
		android:id="@+id/calendar"
		android:numColumns="7"
		android:layout_width="fill_parent"
		android:layout_height="wrap_content">
	</GridView>

</LinearLayout>

File: day_gridcell.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
	xmlns:android="http://schemas.android.com/apk/res/android"
	android:orientation="vertical"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:background="@drawable/calendar_button_selector">

	<Button
		android:id="@+id/calendar_day_gridcell"
		android:layout_gravity="center"
		android:textColor="#FFFFFF"
		android:background="@drawable/calendar_button_selector"
		android:textAppearance="?android:attr/textAppearanceMedium"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content">
	</Button>
	
	<TextView
		android:id="@+id/num_events_per_day"
		style="@style/calendar_event_style"
		android:layout_gravity="right"
		android:layout_width="10dip"
		android:layout_height="10dip">
	</TextView>
</RelativeLayout>

File: SimpleCalendarViewActivity.java

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;

import android.app.Activity;
import android.content.Context;
import android.graphics.Color;
import android.os.Bundle;
import android.text.format.DateFormat;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.TextView;

public class SimpleCalendarViewActivity extends Activity implements OnClickListener
	{
		private static final String tag = "SimpleCalendarViewActivity";

		private ImageView calendarToJournalButton;
		private Button selectedDayMonthYearButton;
		private Button currentMonth;
		private ImageView prevMonth;
		private ImageView nextMonth;
		private GridView calendarView;
		private GridCellAdapter adapter;
		private Calendar _calendar;
		private int month, year;
		private final DateFormat dateFormatter = new DateFormat();
		private static final String dateTemplate = "MMMM yyyy";

		/** Called when the activity is first created. */
		@Override
		public void onCreate(Bundle savedInstanceState)
			{
				super.onCreate(savedInstanceState);
				setContentView(R.layout.simple_calendar_view);

				_calendar = Calendar.getInstance(Locale.getDefault());
				month = _calendar.get(Calendar.MONTH) + 1;
				year = _calendar.get(Calendar.YEAR);
				Log.d(tag, "Calendar Instance:= " + "Month: " + month + " " + "Year: " + year);

				selectedDayMonthYearButton = (Button) this.findViewById(R.id.selectedDayMonthYear);
				selectedDayMonthYearButton.setText("Selected: ");

				prevMonth = (ImageView) this.findViewById(R.id.prevMonth);
				prevMonth.setOnClickListener(this);

				currentMonth = (Button) this.findViewById(R.id.currentMonth);
				currentMonth.setText(dateFormatter.format(dateTemplate, _calendar.getTime()));

				nextMonth = (ImageView) this.findViewById(R.id.nextMonth);
				nextMonth.setOnClickListener(this);

				calendarView = (GridView) this.findViewById(R.id.calendar);

				// Initialised
				adapter = new GridCellAdapter(getApplicationContext(), R.id.calendar_day_gridcell, month, year);
				adapter.notifyDataSetChanged();
				calendarView.setAdapter(adapter);
			}

		/**
		 * 
		 * @param month
		 * @param year
		 */
		private void setGridCellAdapterToDate(int month, int year)
			{
				adapter = new GridCellAdapter(getApplicationContext(), R.id.calendar_day_gridcell, month, year);
				_calendar.set(year, month - 1, _calendar.get(Calendar.DAY_OF_MONTH));
				currentMonth.setText(dateFormatter.format(dateTemplate, _calendar.getTime()));
				adapter.notifyDataSetChanged();
				calendarView.setAdapter(adapter);
			}

		@Override
		public void onClick(View v)
			{
				if (v == prevMonth)
					{
						if (month <= 1)
							{
								month = 12;
								year--;
							}
						else
							{
								month--;
							}
						Log.d(tag, "Setting Prev Month in GridCellAdapter: " + "Month: " + month + " Year: " + year);
						setGridCellAdapterToDate(month, year);
					}
				if (v == nextMonth)
					{
						if (month > 11)
							{
								month = 1;
								year++;
							}
						else
							{
								month++;
							}
						Log.d(tag, "Setting Next Month in GridCellAdapter: " + "Month: " + month + " Year: " + year);
						setGridCellAdapterToDate(month, year);
					}

			}

		@Override
		public void onDestroy()
			{
				Log.d(tag, "Destroying View ...");
				super.onDestroy();
			}

		// ///////////////////////////////////////////////////////////////////////////////////////
		// Inner Class
		public class GridCellAdapter extends BaseAdapter implements OnClickListener
			{
				private static final String tag = "GridCellAdapter";
				private final Context _context;

				private final List<String> list;
				private static final int DAY_OFFSET = 1;
				private final String[] weekdays = new String[]{"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
				private final String[] months = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
				private final int[] daysOfMonth = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
				private final int month, year;
				private int daysInMonth, prevMonthDays;
				private int currentDayOfMonth;
				private int currentWeekDay;
				private Button gridcell;
				private TextView num_events_per_day;
				private final HashMap eventsPerMonthMap;
				private final SimpleDateFormat dateFormatter = new SimpleDateFormat("dd-MMM-yyyy");

				// Days in Current Month
				public GridCellAdapter(Context context, int textViewResourceId, int month, int year)
					{
						super();
						this._context = context;
						this.list = new ArrayList<String>();
						this.month = month;
						this.year = year;

						Log.d(tag, "==> Passed in Date FOR Month: " + month + " " + "Year: " + year);
						Calendar calendar = Calendar.getInstance();
						setCurrentDayOfMonth(calendar.get(Calendar.DAY_OF_MONTH));
						setCurrentWeekDay(calendar.get(Calendar.DAY_OF_WEEK));
						Log.d(tag, "New Calendar:= " + calendar.getTime().toString());
						Log.d(tag, "CurrentDayOfWeek :" + getCurrentWeekDay());
						Log.d(tag, "CurrentDayOfMonth :" + getCurrentDayOfMonth());

						// Print Month
						printMonth(month, year);

						// Find Number of Events
						eventsPerMonthMap = findNumberOfEventsPerMonth(year, month);
					}
				private String getMonthAsString(int i)
					{
						return months[i];
					}

				private String getWeekDayAsString(int i)
					{
						return weekdays[i];
					}

				private int getNumberOfDaysOfMonth(int i)
					{
						return daysOfMonth[i];
					}

				public String getItem(int position)
					{
						return list.get(position);
					}

				@Override
				public int getCount()
					{
						return list.size();
					}

				/**
				 * Prints Month
				 * 
				 * @param mm
				 * @param yy
				 */
				private void printMonth(int mm, int yy)
					{
						Log.d(tag, "==> printMonth: mm: " + mm + " " + "yy: " + yy);
						// The number of days to leave blank at
						// the start of this month.
						int trailingSpaces = 0;
						int leadSpaces = 0;
						int daysInPrevMonth = 0;
						int prevMonth = 0;
						int prevYear = 0;
						int nextMonth = 0;
						int nextYear = 0;

						int currentMonth = mm - 1;
						String currentMonthName = getMonthAsString(currentMonth);
						daysInMonth = getNumberOfDaysOfMonth(currentMonth);

						Log.d(tag, "Current Month: " + " " + currentMonthName + " having " + daysInMonth + " days.");

						// Gregorian Calendar : MINUS 1, set to FIRST OF MONTH
						GregorianCalendar cal = new GregorianCalendar(yy, currentMonth, 1);
						Log.d(tag, "Gregorian Calendar:= " + cal.getTime().toString());

						if (currentMonth == 11)
							{
								prevMonth = currentMonth - 1;
								daysInPrevMonth = getNumberOfDaysOfMonth(prevMonth);
								nextMonth = 0;
								prevYear = yy;
								nextYear = yy + 1;
								Log.d(tag, "*->PrevYear: " + prevYear + " PrevMonth:" + prevMonth + " NextMonth: " + nextMonth + " NextYear: " + nextYear);
							}
						else if (currentMonth == 0)
							{
								prevMonth = 11;
								prevYear = yy - 1;
								nextYear = yy;
								daysInPrevMonth = getNumberOfDaysOfMonth(prevMonth);
								nextMonth = 1;
								Log.d(tag, "**--> PrevYear: " + prevYear + " PrevMonth:" + prevMonth + " NextMonth: " + nextMonth + " NextYear: " + nextYear);
							}
						else
							{
								prevMonth = currentMonth - 1;
								nextMonth = currentMonth + 1;
								nextYear = yy;
								prevYear = yy;
								daysInPrevMonth = getNumberOfDaysOfMonth(prevMonth);
								Log.d(tag, "***---> PrevYear: " + prevYear + " PrevMonth:" + prevMonth + " NextMonth: " + nextMonth + " NextYear: " + nextYear);
							}

						// Compute how much to leave before before the first day of the
						// month.
						// getDay() returns 0 for Sunday.
						int currentWeekDay = cal.get(Calendar.DAY_OF_WEEK) - 1;
						trailingSpaces = currentWeekDay;

						Log.d(tag, "Week Day:" + currentWeekDay + " is " + getWeekDayAsString(currentWeekDay));
						Log.d(tag, "No. Trailing space to Add: " + trailingSpaces);
						Log.d(tag, "No. of Days in Previous Month: " + daysInPrevMonth);

						if (cal.isLeapYear(cal.get(Calendar.YEAR)) && mm == 1)
							{
								++daysInMonth;
							}

						// Trailing Month days
						for (int i = 0; i < trailingSpaces; i++)
							{
								Log.d(tag, "PREV MONTH:= " + prevMonth + " => " + getMonthAsString(prevMonth) + " " + String.valueOf((daysInPrevMonth - trailingSpaces + DAY_OFFSET) + i));
								list.add(String.valueOf((daysInPrevMonth - trailingSpaces + DAY_OFFSET) + i) + "-GREY" + "-" + getMonthAsString(prevMonth) + "-" + prevYear);
							}

						// Current Month Days
						for (int i = 1; i <= daysInMonth; i++)
							{
								Log.d(currentMonthName, String.valueOf(i) + " " + getMonthAsString(currentMonth) + " " + yy);
								if (i == getCurrentDayOfMonth())
									{
										list.add(String.valueOf(i) + "-BLUE" + "-" + getMonthAsString(currentMonth) + "-" + yy);
									}
								else
									{
										list.add(String.valueOf(i) + "-WHITE" + "-" + getMonthAsString(currentMonth) + "-" + yy);
									}
							}

						// Leading Month days
						for (int i = 0; i < list.size() % 7; i++)
							{
								Log.d(tag, "NEXT MONTH:= " + getMonthAsString(nextMonth));
								list.add(String.valueOf(i + 1) + "-GREY" + "-" + getMonthAsString(nextMonth) + "-" + nextYear);
							}
					}

				/**
				 * NOTE: YOU NEED TO IMPLEMENT THIS PART Given the YEAR, MONTH, retrieve
				 * ALL entries from a SQLite database for that month. Iterate over the
				 * List of All entries, and get the dateCreated, which is converted into
				 * day.
				 * 
				 * @param year
				 * @param month
				 * @return
				 */
				private HashMap findNumberOfEventsPerMonth(int year, int month)
					{
						HashMap map = new HashMap<String, Integer>();
						// DateFormat dateFormatter2 = new DateFormat();
						//						
						// String day = dateFormatter2.format("dd", dateCreated).toString();
						//
						// if (map.containsKey(day))
						// {
						// Integer val = (Integer) map.get(day) + 1;
						// map.put(day, val);
						// }
						// else
						// {
						// map.put(day, 1);
						// }
						return map;
					}

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

				@Override
				public View getView(int position, View convertView, ViewGroup parent)
					{
						View row = convertView;
						if (row == null)
							{
								LayoutInflater inflater = (LayoutInflater) _context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
								row = inflater.inflate(R.layout.calendar_day_gridcell, parent, false);
							}

						// Get a reference to the Day gridcell
						gridcell = (Button) row.findViewById(R.id.calendar_day_gridcell);
						gridcell.setOnClickListener(this);

						// ACCOUNT FOR SPACING

						Log.d(tag, "Current Day: " + getCurrentDayOfMonth());
						String[] day_color = list.get(position).split("-");
						String theday = day_color[0];
						String themonth = day_color[2];
						String theyear = day_color[3];
						if ((!eventsPerMonthMap.isEmpty()) && (eventsPerMonthMap != null))
							{
								if (eventsPerMonthMap.containsKey(theday))
									{
										num_events_per_day = (TextView) row.findViewById(R.id.num_events_per_day);
										Integer numEvents = (Integer) eventsPerMonthMap.get(theday);
										num_events_per_day.setText(numEvents.toString());
									}
							}

						// Set the Day GridCell
						gridcell.setText(theday);
						gridcell.setTag(theday + "-" + themonth + "-" + theyear);
						Log.d(tag, "Setting GridCell " + theday + "-" + themonth + "-" + theyear);

						if (day_color[1].equals("GREY"))
							{
								gridcell.setTextColor(Color.LTGRAY);
							}
						if (day_color[1].equals("WHITE"))
							{
								gridcell.setTextColor(Color.WHITE);
							}
						if (day_color[1].equals("BLUE"))
							{
								gridcell.setTextColor(getResources().getColor(R.color.static_text_color));
							}
						return row;
					}
				@Override
				public void onClick(View view)
					{
						String date_month_year = (String) view.getTag();
						selectedDayMonthYearButton.setText("Selected: " + date_month_year);

						try
							{
								Date parsedDate = dateFormatter.parse(date_month_year);
								Log.d(tag, "Parsed Date: " + parsedDate.toString());

							}
						catch (ParseException e)
							{
								e.printStackTrace();
							}
					}

				public int getCurrentDayOfMonth()
					{
						return currentDayOfMonth;
					}

				private void setCurrentDayOfMonth(int currentDayOfMonth)
					{
						this.currentDayOfMonth = currentDayOfMonth;
					}
				public void setCurrentWeekDay(int currentWeekDay)
					{
						this.currentWeekDay = currentWeekDay;
					}
				public int getCurrentWeekDay()
					{
						return currentWeekDay;
					}
			}
	}