How to Create Custom Calendar in Android Example

How to Create Custom Calendar in Android Example? In this tutorial, we will create a custom calendar that you can build in Android Studio using Linear Layouts and add an onClickListener to selected a Date.

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Our calendar widget will contain 7 columns for the week and 7 rows for month dates. Here is an image of what we will build:

This project is a fork from Github, link here.

How to Create Custom Calendar in Android Example

Getting Started

Create a new Empty MainActivity project in Android Studio with xml layout activity_main.xml.

To create a layout as shown in the image above, we will create a need layout resource file in res > layout named simple_calendar.xml.

For calendar layout, we need LinearLayout inside which using TextViews and other nested LinearLayout we will create the calendar. Here is the XML code of the same.

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

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:gravity="center"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/current_date"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="@color/green"
            android:textSize="28sp" />

        <TextView
            android:id="@+id/current_month"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:paddingLeft="10dp"
            android:textColor="@color/green"
            android:textSize="28sp" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:weightSum="7">

        <Button
            android:id="@+id/button5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="@android:color/transparent"
            android:text="S"
            android:textColor="@color/green"
            android:textSize="16sp" />

        <Button
            android:id="@+id/button4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="@android:color/transparent"
            android:text="S"
            android:textColor="@color/green"
            android:textSize="16sp" />

        <Button
            android:id="@+id/button10"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="@android:color/transparent"
            android:text="M"
            android:textColor="@color/green"
            android:textSize="16sp" />

        <Button
            android:id="@+id/button9"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="@android:color/transparent"
            android:text="T"
            android:textColor="@color/green"
            android:textSize="16sp" />

        <Button
            android:id="@+id/button8"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="@android:color/transparent"
            android:text="W"
            android:textColor="@color/green"
            android:textSize="16sp" />

        <Button
            android:id="@+id/button7"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="@android:color/transparent"
            android:text="T"
            android:textColor="@color/green"
            android:textSize="16sp" />

        <Button
            android:id="@+id/button6"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="@android:color/transparent"
            android:text="F"
            android:textColor="@color/green"
            android:textSize="16sp" />

    </LinearLayout>

    <LinearLayout
        android:id="@+id/calendar_week_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:weightSum="7" />

    <LinearLayout
        android:id="@+id/calendar_week_2"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:weightSum="7" />

    <LinearLayout
        android:id="@+id/calendar_week_3"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:weightSum="7" />

    <LinearLayout
        android:id="@+id/calendar_week_4"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:weightSum="7" />

    <LinearLayout
        android:id="@+id/calendar_week_5"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:weightSum="7" />

    <LinearLayout
        android:id="@+id/calendar_week_6"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:weightSum="7" />

</LinearLayout>

Now create a java file named SimpleCalendar.java which extends LinearLayout. Here is the code for the same:

package com.example.customcalendar;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Color;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.support.annotation.RequiresApi;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
import java.util.Calendar;


public class SimpleCalendar extends LinearLayout {
    
    private static final String CUSTOM_GREY = "#a0a0a0";
    private static final String[] ENG_MONTH_NAMES = {"January", "February", "March", "April",
            "May", "June", "July", "August",
            "September", "October", "November", "December"};

    private Button selectedDayButton;
    private Button[] days;
    LinearLayout weekOneLayout;
    LinearLayout weekTwoLayout;
    LinearLayout weekThreeLayout;
    LinearLayout weekFourLayout;
    LinearLayout weekFiveLayout;
    LinearLayout weekSixLayout;
    private LinearLayout[] weeks;

    private int currentDateDay, chosenDateDay, currentDateMonth,
            chosenDateMonth, currentDateYear, chosenDateYear,
            pickedDateDay, pickedDateMonth, pickedDateYear;
    int userMonth, userYear;
    private DayClickListener mListener;

    private Calendar calendar;
    LinearLayout.LayoutParams defaultButtonParams;
    private LinearLayout.LayoutParams userButtonParams;

    public SimpleCalendar(Context context) {
        super(context);
        init(context);
    }

    public SimpleCalendar(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public SimpleCalendar(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(context);
    }


    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    public SimpleCalendar(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
        init(context);
    }

    @SuppressLint("SetTextI18n")
    private void init(Context context) {
        DisplayMetrics metrics = getResources().getDisplayMetrics();

        View view = LayoutInflater.from(context).inflate(R.layout.simple_calendar, this, true);
        calendar = Calendar.getInstance();

        weekOneLayout = view.findViewById(R.id.calendar_week_1);
        weekTwoLayout = view.findViewById(R.id.calendar_week_2);
        weekThreeLayout = view.findViewById(R.id.calendar_week_3);
        weekFourLayout = view.findViewById(R.id.calendar_week_4);
        weekFiveLayout = view.findViewById(R.id.calendar_week_5);
        weekSixLayout = view.findViewById(R.id.calendar_week_6);
        TextView currentDate = view.findViewById(R.id.current_date);
        TextView currentMonth = view.findViewById(R.id.current_month);

        currentDateDay = chosenDateDay = calendar.get(Calendar.DAY_OF_MONTH);

        if (userMonth != 0 && userYear != 0) {
            currentDateMonth = chosenDateMonth = userMonth;
            currentDateYear = chosenDateYear = userYear;
        } else {
            currentDateMonth = chosenDateMonth = calendar.get(Calendar.MONTH);
            currentDateYear = chosenDateYear = calendar.get(Calendar.YEAR);
        }

        currentDate.setText("" + currentDateDay);
        currentMonth.setText(ENG_MONTH_NAMES[currentDateMonth]);

        initializeDaysWeeks();
        if (userButtonParams != null) {
            defaultButtonParams = userButtonParams;
        } else {
            defaultButtonParams = getdaysLayoutParams();
        }
        addDaysinCalendar(defaultButtonParams, context, metrics);

        initCalendarWithDate(chosenDateYear, chosenDateMonth, chosenDateDay);

    }

    private void initializeDaysWeeks() {
        weeks = new LinearLayout[6];
        days = new Button[6 * 7];

        weeks[0] = weekOneLayout;
        weeks[1] = weekTwoLayout;
        weeks[2] = weekThreeLayout;
        weeks[3] = weekFourLayout;
        weeks[4] = weekFiveLayout;
        weeks[5] = weekSixLayout;
    }

    private void initCalendarWithDate(int year, int month, int day) {
        if (calendar == null)
            calendar = Calendar.getInstance();
        calendar.set(year, month, day);

        int daysInCurrentMonth = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);

        chosenDateYear = year;
        chosenDateMonth = month;
        chosenDateDay = day;

        calendar.set(year, month, 1);
        int firstDayOfCurrentMonth = calendar.get(Calendar.DAY_OF_WEEK);

        calendar.set(year, month, calendar.getActualMaximum(Calendar.DAY_OF_MONTH));

        int dayNumber = 1;
        int daysLeftInFirstWeek;
        int indexOfDayAfterLastDayOfMonth;

        if (firstDayOfCurrentMonth != 1) {
            daysLeftInFirstWeek = firstDayOfCurrentMonth;
            indexOfDayAfterLastDayOfMonth = daysLeftInFirstWeek + daysInCurrentMonth;
            for (int i = firstDayOfCurrentMonth; i < firstDayOfCurrentMonth + daysInCurrentMonth; ++i) {
                if (currentDateMonth == chosenDateMonth
                        && currentDateYear == chosenDateYear
                        && dayNumber == currentDateDay) {
                    days[i].setBackgroundColor(getResources().getColor(R.color.pink));
                    days[i].setTextColor(Color.WHITE);
                } else {
                    days[i].setTextColor(Color.BLACK);
                    days[i].setBackgroundColor(Color.TRANSPARENT);
                }

                int[] dateArr = new int[3];
                dateArr[0] = dayNumber;
                dateArr[1] = chosenDateMonth;
                dateArr[2] = chosenDateYear;
                days[i].setTag(dateArr);
                days[i].setText(String.valueOf(dayNumber));

                days[i].setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        onDayClick(v);
                    }
                });
                ++dayNumber;
            }
        } else {
            daysLeftInFirstWeek = 8;
            indexOfDayAfterLastDayOfMonth = daysLeftInFirstWeek + daysInCurrentMonth;
            for (int i = 8; i < 8 + daysInCurrentMonth; ++i) {
                if (currentDateMonth == chosenDateMonth
                        && currentDateYear == chosenDateYear
                        && dayNumber == currentDateDay) {
                    days[i].setBackgroundColor(getResources().getColor(R.color.pink));
                    days[i].setTextColor(Color.WHITE);
                } else {
                    days[i].setTextColor(Color.BLACK);
                    days[i].setBackgroundColor(Color.TRANSPARENT);
                }

                int[] dateArr = new int[3];
                dateArr[0] = dayNumber;
                dateArr[1] = chosenDateMonth;
                dateArr[2] = chosenDateYear;
                days[i].setTag(dateArr);
                days[i].setText(String.valueOf(dayNumber));

                days[i].setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        onDayClick(v);
                    }
                });
                ++dayNumber;
            }
        }

        if (month > 0)
            calendar.set(year, month - 1, 1);
        else
            calendar.set(year - 1, 11, 1);
        int daysInPreviousMonth = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);

        for (int i = daysLeftInFirstWeek - 1; i >= 0; --i) {
            int[] dateArr = new int[3];

            if (chosenDateMonth > 0) {
                if (currentDateMonth != chosenDateMonth - 1
                        || currentDateYear != chosenDateYear
                        || daysInPreviousMonth != currentDateDay) {
                            days[i].setBackgroundColor(Color.TRANSPARENT);
                        }

                dateArr[0] = daysInPreviousMonth;
                dateArr[1] = chosenDateMonth - 1;
                dateArr[2] = chosenDateYear;
            } else {
                if (currentDateMonth != 11
                        || currentDateYear != chosenDateYear - 1
                        || daysInPreviousMonth != currentDateDay) {
                            days[i].setBackgroundColor(Color.TRANSPARENT);
                        }

                dateArr[0] = daysInPreviousMonth;
                dateArr[1] = 11;
                dateArr[2] = chosenDateYear - 1;
            }

            days[i].setTag(dateArr);
            days[i].setText(String.valueOf(daysInPreviousMonth--));
            days[i].setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    onDayClick(v);
                }
            });
        }

        int nextMonthDaysCounter = 1;
        for (int i = indexOfDayAfterLastDayOfMonth; i < days.length; ++i) {
            int[] dateArr = new int[3];

            if (chosenDateMonth < 11) {
                if (currentDateMonth == chosenDateMonth + 1
                        && currentDateYear == chosenDateYear
                        && nextMonthDaysCounter == currentDateDay) {
                    days[i].setBackgroundColor(getResources().getColor(R.color.pink));
                } else {
                    days[i].setBackgroundColor(Color.TRANSPARENT);
                }

                dateArr[0] = nextMonthDaysCounter;
                dateArr[1] = chosenDateMonth + 1;
                dateArr[2] = chosenDateYear;
            } else {
                if (currentDateMonth == 0
                        && currentDateYear == chosenDateYear + 1
                        && nextMonthDaysCounter == currentDateDay) {
                    days[i].setBackgroundColor(getResources().getColor(R.color.pink));
                } else {
                    days[i].setBackgroundColor(Color.TRANSPARENT);
                }

                dateArr[0] = nextMonthDaysCounter;
                dateArr[1] = 0;
                dateArr[2] = chosenDateYear + 1;
            }

            days[i].setTag(dateArr);
            days[i].setTextColor(Color.parseColor(CUSTOM_GREY));
            days[i].setText(String.valueOf(nextMonthDaysCounter++));
            days[i].setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    onDayClick(v);
                }
            });
        }

        calendar.set(chosenDateYear, chosenDateMonth, chosenDateDay);
    }

    public void onDayClick(View view) {
        mListener.onDayClick(view);

        if (selectedDayButton != null) {
            if (chosenDateYear == currentDateYear
                    && chosenDateMonth == currentDateMonth
                    && pickedDateDay == currentDateDay) {
                selectedDayButton.setBackgroundColor(getResources().getColor(R.color.pink));
                selectedDayButton.setTextColor(Color.WHITE);
            } else {
                selectedDayButton.setBackgroundColor(Color.TRANSPARENT);
                if (selectedDayButton.getCurrentTextColor() != Color.RED) {
                    selectedDayButton.setTextColor(getResources()
                            .getColor(R.color.calendar_number));
                }
            }
        }

        selectedDayButton = (Button) view;
        if (selectedDayButton.getTag() != null) {
            int[] dateArray = (int[]) selectedDayButton.getTag();
            pickedDateDay = dateArray[0];
            pickedDateMonth = dateArray[1];
            pickedDateYear = dateArray[2];
        }

        if (pickedDateYear == currentDateYear
                && pickedDateMonth == currentDateMonth
                && pickedDateDay == currentDateDay) {
            selectedDayButton.setBackgroundColor(getResources().getColor(R.color.pink));
            selectedDayButton.setTextColor(Color.WHITE);
        } else {
            selectedDayButton.setBackgroundColor(getResources().getColor(R.color.grey));
            if (selectedDayButton.getCurrentTextColor() != Color.RED) {
                selectedDayButton.setTextColor(Color.WHITE);
            }
        }
    }

    private void addDaysinCalendar(LayoutParams buttonParams, Context context,
                                   DisplayMetrics metrics) {
        int engDaysArrayCounter = 0;

        for (int weekNumber = 0; weekNumber < 6; ++weekNumber) {
            for (int dayInWeek = 0; dayInWeek < 7; ++dayInWeek) {
                final Button day = new Button(context);
                day.setTextColor(Color.parseColor(CUSTOM_GREY));
                day.setBackgroundColor(Color.TRANSPARENT);
                day.setLayoutParams(buttonParams);
                day.setTextSize((int) metrics.density * 8);
                day.setSingleLine();

                days[engDaysArrayCounter] = day;
                weeks[weekNumber].addView(day);

                ++engDaysArrayCounter;
            }
        }
    }

    private LayoutParams getdaysLayoutParams() {
        LinearLayout.LayoutParams buttonParams = new LinearLayout.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.MATCH_PARENT);
        buttonParams.weight = 1;
        return buttonParams;
    }

    public void setUserDaysLayoutParams(LinearLayout.LayoutParams userButtonParams) {
        this.userButtonParams = userButtonParams;
    }

    public void setUserCurrentMonthYear(int userMonth, int userYear) {
        this.userMonth = userMonth;
        this.userYear = userYear;
    }

    public void setDayBackground(Drawable userDrawable) {
        Drawable userDrawable1 = userDrawable;
    }

    public interface DayClickListener {
        void onDayClick(View view);
    }

    public void setCallBack(DayClickListener mListener) {
        this.mListener = mListener;
    }

}

Now in activity_main.xml you can easily create a SimpleCalendar widget. Set its height and width as they are the required attributes. Here is the code for the same.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:orientation="horizontal">

   <com.example.customcalendar.SimpleCalendar
       android:id="@+id/square_day"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"/>

</LinearLayout>

Now in MainActivity.java, create SimpleCalendar object and using findViewByID link it with the XML widget . Here is the code for the same:

package com.example.customcalendar;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;

import java.util.Calendar;

public class MainActivity extends AppCompatActivity {

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

        SimpleCalendar simpleCalendar = findViewById(R.id.square_day);
        Calendar calendar = Calendar.getInstance();
        // Get current month
        int month = calendar.get(Calendar.MONTH);

        //Get current Year
        int year = calendar.get(Calendar.YEAR);

        simpleCalendar.setUserCurrentMonthYear(month,year);
        simpleCalendar.setCallBack(new SimpleCalendar.DayClickListener() {
            @Override
            public void onDayClick(View view) {
               // Create on Click event here.
            }
        });
    }

}

Interested in implementing calendar library built by other android developers, see Top 20 Android Calendar Library here.

Interested in implementing Rating feature in your app, see here: Android Rate App feature implementation.

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