Android Calendar

calendar.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:background="@drawable/background"
    android:orientation="vertical" >

    <RelativeLayout
        android:id="@+id/header"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:background="@drawable/calendar_top" >

        <RelativeLayout
            android:id="@+id/previous"
            android:layout_width="40dip"
            android:layout_height="30dip"
            android:layout_alignParentLeft="true" >

            <ImageView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:background="@drawable/arrow_left" />
        </RelativeLayout>

        <TextView
            android:id="@+id/title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:layout_marginTop="5dip"
            android:textColor="#000000"
            android:textSize="18dip"
            android:textStyle="bold" />

        <RelativeLayout
            android:id="@+id/next"
            android:layout_width="40dip"
            android:layout_height="30dip"
            android:layout_alignParentRight="true" >

            <ImageView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:background="@drawable/arrow_right" />
        </RelativeLayout>
    </RelativeLayout>

    <GridView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/gridview"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:listSelector="@android:color/transparent"
        android:numColumns="7"
        android:stretchMode="columnWidth" />

</LinearLayout>

calendar_item

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/calendar_cell"
    android:gravity="center"
    android:orientation="vertical"
    android:padding="2dip" >

    <TextView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/date"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#0000D7"
        android:textSize="14dip"
        android:textStyle="bold" >
    </TextView>

    <ImageView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/date_icon"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/dot"
        android:visibility="gone" />

</LinearLayout>

CalendarAdapter

package com.examples.android.calendar;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;

import android.content.Context;
import android.graphics.Color;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class CalendarAdapter extends BaseAdapter {
	private Context mContext;

	private java.util.Calendar month;
	public Calendar pmonth; // calendar instance for previous month
	/**
	 * calendar instance for previous month for getting complete view
	 */
	public Calendar pmonthmaxset;
	private Calendar selectedDate;
	int firstDay;
	int maxWeeknumber;
	int maxP;
	int calMaxP;
	int lastWeekDay;
	int leftDays;
	int mnthlength;
	String itemvalue, curentDateString;
	DateFormat df;

	private ArrayList<String> items;
	public static List<String> dayString;
	private View previousView;

	// private List<String> mnthString;

	public CalendarAdapter(Context c, Calendar monthCalendar) {
		CalendarAdapter.dayString = new ArrayList<String>();
		month = monthCalendar;
		pmonth = (Calendar) month.clone();
		selectedDate = (Calendar) monthCalendar.clone();
		mContext = c;
		month.set(Calendar.DAY_OF_MONTH, 1);
		this.items = new ArrayList<String>();
		df = new SimpleDateFormat("yyyy-MM-dd");
		curentDateString = df.format(selectedDate.getTime());
		refreshDays();
	}

	public void setItems(ArrayList<String> items) {
		for (int i = 0; i != items.size(); i++) {
			if (items.get(i).length() == 1) {
				items.set(i, "0" + items.get(i));
			}
		}
		this.items = items;
	}

	public int getCount() {
		return dayString.size();
	}

	public Object getItem(int position) {
		return dayString.get(position);
	}

	public long getItemId(int position) {
		return 0;
	}

	// create a new view for each item referenced by the Adapter
	public View getView(int position, View convertView, ViewGroup parent) {
		View v = convertView;
		TextView dayView;
		if (convertView == null) { // if it's not recycled, initialize some
									// attributes
			LayoutInflater vi = (LayoutInflater) mContext
					.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
			v = vi.inflate(R.layout.calendar_item, null);

		}
		dayView = (TextView) v.findViewById(R.id.date);
		// separates daystring into parts.
		String[] separatedTime = dayString.get(position).split("-");
		// taking last part of date. ie; 2 from 2012-12-02
		String gridvalue = separatedTime[2].replaceFirst("^0*", "");
		// checking whether the day is in current month or not.
		if ((Integer.parseInt(gridvalue) > 1) && (position < firstDay)) {
			// setting offdays to white color.
			dayView.setTextColor(Color.WHITE);
			dayView.setClickable(false);
			dayView.setFocusable(false);
			// i++;
		} else if ((Integer.parseInt(gridvalue) < 7) && (position > 28)) {
			dayView.setTextColor(Color.WHITE);
			dayView.setClickable(false);
			dayView.setFocusable(false);
			// i++;
		} else {
			// setting curent month's days in blue color.
			dayView.setTextColor(Color.BLUE);
		}

		if (dayString.get(position).equals(curentDateString)) {
			setSelected(v);
			previousView = v;
		} else {
			v.setBackgroundResource(R.drawable.list_item_background);
		}
		dayView.setText(gridvalue);

		// create date string for comparison
		String date = dayString.get(position);

		if (date.length() == 1) {
			date = "0" + date;
		}
		String monthStr = "" + (month.get(Calendar.MONTH) + 1);
		if (monthStr.length() == 1) {
			monthStr = "0" + monthStr;
		}

		// show icon if date is not empty and it exists in the items array
		ImageView iw = (ImageView) v.findViewById(R.id.date_icon);
		if (date.length() > 0 && items != null && items.contains(date)) {
			iw.setVisibility(View.VISIBLE);
		} else {
			iw.setVisibility(View.INVISIBLE);
		}
		return v;
	}

	public View setSelected(View view) {
		if (previousView != null) {
			previousView.setBackgroundResource(R.drawable.list_item_background);
		}
		previousView = view;
		view.setBackgroundResource(R.drawable.calendar_cel_selectl);
		return view;
	}

	public void refreshDays() {
		// clear items
		items.clear();
		dayString.clear();
		// month start day. ie; sun, mon, etc
		firstDay = month.get(Calendar.DAY_OF_WEEK);
		// finding number of weeks in current month.
		maxWeeknumber = month.getActualMaximum(Calendar.WEEK_OF_MONTH);
		// allocating maximum row number for the gridview.
		mnthlength = maxWeeknumber * 7;
		maxP = getMaxP(); // previous month maximum day 31,30....
		calMaxP = maxP - (firstDay - 1);// calendar offday starting 24,25 ...
		/**
		 * Calendar instance for getting a complete gridview including the three
		 * month's (previous,current,next) dates.
		 */
		pmonthmaxset = (Calendar) pmonth.clone();
		/**
		 * setting the start date as previous month's required date.
		 */
		pmonthmaxset.set(Calendar.DATE, calMaxP + 1);

		/**
		 * filling calendar gridview.
		 */
		for (int n = 0; n < mnthlength; n++) {
			itemvalue = df.format(pmonthmaxset.getTime());
			pmonthmaxset.add(Calendar.DATE, 1);
			dayString.add(itemvalue);

		}
	}

	private int getMaxP() {
		int maxP;
		if (month.get(Calendar.MONTH) == month.getActualMinimum(Calendar.MONTH)) {
			pmonth.set((month.get(Calendar.YEAR) - 1),
					month.getActualMaximum(Calendar.MONTH), 1);
		} else {
			pmonth.set(Calendar.MONTH, month.get(Calendar.MONTH) - 1);
		}
		maxP = pmonth.getActualMaximum(Calendar.DAY_OF_MONTH);
		Log.i("", "maxP is :         "+maxP);
		Log.e("", "calendar month is :            "+Calendar.MONTH);
		return maxP;
	}

}

CalendarView.java

package com.examples.android.calendar;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.GridView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;

public class CalendarView extends Activity {

	public Calendar month, itemmonth;// calendar instances.

	public CalendarAdapter adapter;// adapter instance
	public Handler handler;// for grabbing some event values for showing the dot
							// marker.
	public ArrayList<String> items; // container to store calendar items which
									// needs showing the event marker

	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.calendar);

		month = Calendar.getInstance();
		itemmonth = (Calendar) month.clone();

		items = new ArrayList<String>();
		adapter = new CalendarAdapter(this, month);

		GridView gridview = (GridView) findViewById(R.id.gridview);
		gridview.setAdapter(adapter);

		handler = new Handler();
		handler.post(calendarUpdater);

		TextView title = (TextView) findViewById(R.id.title);
		title.setText(android.text.format.DateFormat.format("MMMM yyyy", month));

		RelativeLayout previous = (RelativeLayout) findViewById(R.id.previous);

		previous.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				setPreviousMonth();
				refreshCalendar();
			}
		});

		RelativeLayout next = (RelativeLayout) findViewById(R.id.next);
		next.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				setNextMonth();
				refreshCalendar();

			}
		});

		gridview.setOnItemClickListener(new OnItemClickListener() {
			public void onItemClick(AdapterView<?> parent, View v,
					int position, long id) {

				((CalendarAdapter) parent.getAdapter()).setSelected(v);
				String selectedGridDate = CalendarAdapter.dayString
						.get(position);
				String[] separatedTime = selectedGridDate.split("-");
				String gridvalueString = separatedTime[2].replaceFirst("^0*",
						"");// taking last part of date. ie; 2 from 2012-12-02.
				int gridvalue = Integer.parseInt(gridvalueString);
				// navigate to next or previous month on clicking offdays.
				if ((gridvalue > 10) && (position < 8)) {
					setPreviousMonth();
					refreshCalendar();
				} else if ((gridvalue < 7) && (position > 28)) {
					setNextMonth();
					refreshCalendar();
				}
				((CalendarAdapter) parent.getAdapter()).setSelected(v);

				showToast(selectedGridDate);

			}
		});
	}

	protected void setNextMonth() {
		if (month.get(Calendar.MONTH) == month.getActualMaximum(Calendar.MONTH)) {
			month.set((month.get(Calendar.YEAR) + 1),
					month.getActualMinimum(Calendar.MONTH), 1);
		} else {
			month.set(Calendar.MONTH, month.get(Calendar.MONTH) + 1);
		}

	}

	protected void setPreviousMonth() {
		if (month.get(Calendar.MONTH) == month.getActualMinimum(Calendar.MONTH)) {
			month.set((month.get(Calendar.YEAR) - 1),
					month.getActualMaximum(Calendar.MONTH), 1);
		} else {
			month.set(Calendar.MONTH, month.get(Calendar.MONTH) - 1);
		}

	}

	protected void showToast(String string) {
		Toast.makeText(this, string, Toast.LENGTH_SHORT).show();

	}

	public void refreshCalendar() {
		TextView title = (TextView) findViewById(R.id.title);

		adapter.refreshDays();
		adapter.notifyDataSetChanged();
		handler.post(calendarUpdater); // generate some calendar items

		title.setText(android.text.format.DateFormat.format("MMMM yyyy", month));
	}

	public Runnable calendarUpdater = new Runnable() {

		@Override
		public void run() {
			items.clear();

			// Print dates of the current week
			DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
			String itemvalue;
			for (int i = 0; i < 7; i++) {
				itemvalue = df.format(itemmonth.getTime());
				itemmonth.add(Calendar.DATE, 1);
				items.add("2012-09-12");
				items.add("2012-10-07");
				items.add("2012-10-15");
				items.add("2012-10-20");
				items.add("2012-11-30");
				items.add("2012-11-28");
			}

			adapter.setItems(items);
			adapter.notifyDataSetChanged();
		}
	};
}

how to display clicked date selected when come back any month