Custom Calendar View Android | Project Java Files

Welcome to the third part of Custom Calendar View in Android. In the second part we created the project settings and XML layout files. Now, we will build the project Java files and start with application database.

The first step in this part is creating SQLite open helper class. In this class we can create SQLite database and also insert, delete and select methods which are required for our project.

Custom Calendar Open Helper Class Java File

First, we need to create a public Java class that contains public static final variables for database version, columns and tables names. You can copy the following code.

public class DBStructure {
public static final String DB_NAME = "EVENTS_DB";
public static final int DB_VERSION = 2;
public static final String EVENT_TABLE_NAME="eventstable" ;
public static final String EVENT = "event";
public static final String TIME = "time";
public static final String DATE = "date";
public static final String MONTH = "month";
public static final String YEAR = "year";
public static final String ID = "ID";
public static final String Notify = "notify";

}

Next, we need to create Database Open Helper class. To know more about SQLiteOpenHelper class click her. For that, create a new Java class and name it DBOpenHelper and this class will extend SQLiteOpenHelper class. After inheritance the red line appears nuder class name click “alt” and “enter” buttons to override two methods one for onCreate and the another for onUpgrade. After that we need to create the constructors as the following code.

public class DBOpenHelper extends SQLiteOpenHelper {

private static final String CREATE_EVENTS_TABLE = "create table "+DBStructure.EVENT_TABLE_NAME+"(ID INTEGER PRIMARY KEY AUTOINCREMENT, "
+DBStructure.EVENT+" TEXT, "+DBStructure.TIME+" TEXT, "+DBStructure.DATE+" TEXT, "+DBStructure.MONTH+" TEXT, "
+DBStructure.YEAR+" TEXT, "+DBStructure.Notify+" TEXT)";
private static final String DROP_EVENTS_TABLE= "DROP TABLE IF EXISTS "+DBStructure.EVENT_TABLE_NAME;



public DBOpenHelper(@Nullable Context context) {
super(context, DBStructure.DB_NAME, null, DBStructure.DB_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_EVENTS_TABLE);

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL(DROP_EVENTS_TABLE);
onCreate(db);

}


public void SaveEvent(String event,String time,String date,String month,String year,String notify,SQLiteDatabase database){
ContentValues contentValues = new ContentValues();
contentValues.put(DBStructure.EVENT,event);
contentValues.put(DBStructure.TIME,time);
contentValues.put(DBStructure.DATE,date);
contentValues.put(DBStructure.MONTH,month);
contentValues.put(DBStructure.YEAR,year);
contentValues.put(DBStructure.Notify,notify);
database.insert(DBStructure.EVENT_TABLE_NAME,null,contentValues);

}

public Cursor ReadEvents(String date,SQLiteDatabase database){
String [] Projections = {DBStructure.EVENT,DBStructure.TIME,DBStructure.DATE,DBStructure.MONTH,DBStructure.YEAR};
String Selection = DBStructure.DATE +"=?";
String [] SelectionArgs = {date};

return database.query(DBStructure.EVENT_TABLE_NAME,Projections,Selection,SelectionArgs,null,null,null);
}

public Cursor ReadIDEvents(String date,String event, String time,SQLiteDatabase database){
String [] Projections = {DBStructure.ID,DBStructure.Notify,DBStructure.TIME};
String Selection = DBStructure.DATE +"=? and "+DBStructure.EVENT+"=? and "+DBStructure.TIME+"=?";
String [] SelectionArgs = {date,event,time};

return database.query(DBStructure.EVENT_TABLE_NAME,Projections,Selection,SelectionArgs,null,null,null);
}


public Cursor ReadEventsperMonth(String month,String year,SQLiteDatabase database){
String [] Projections = {DBStructure.EVENT,DBStructure.TIME,DBStructure.DATE,DBStructure.MONTH,DBStructure.YEAR};
String Selection = DBStructure.MONTH +"=? and "+DBStructure.YEAR+"=?";
String [] SelectionArgs = {month,year};
return database.query(DBStructure.EVENT_TABLE_NAME,Projections,Selection,SelectionArgs,null,null,null);
}



public void deleteEvent(String event,String date,String time,SQLiteDatabase database){
String selection = DBStructure.EVENT+"=? and "+DBStructure.DATE+"=? and "+DBStructure.TIME+"=?";
String[] selectionArg = {event,date,time};
database.delete(DBStructure.EVENT_TABLE_NAME,selection,selectionArg);
}


public void updateEvent(String date,String event, String time,String notify,SQLiteDatabase database){
ContentValues contentValues = new ContentValues();
contentValues.put(DBStructure.Notify,notify);
String Selection = DBStructure.DATE +"=? and "+DBStructure.EVENT+"=? and "+DBStructure.TIME+"=?";
String [] SelectionArgs = {date,event,time};
database.update(DBStructure.EVENT_TABLE_NAME,contentValues,Selection,SelectionArgs);
}



}

---

Custom Calendar View Java File

Next, custom calendar view needs to inflate the above XML layout with java class that extents LinearLayout. The Linear Layout super class overrides three constructors. The first, is context constructor and we will use it when to cast the context when we implement it in activity or fragment. The second is with context and attributeSet. With the attributeSet constructor we will initialize the context, initialize the layout and setup the calendar view and buttons click and also the click and long click listener of the grid layout.

Initialize layout method

In this method we will inflate the custom_calendar_layout.xml file and findViewById for buttons current date text view and grid view.

//this part of code is for clarification the final code is coming below.
private void IntializeLayout(){
LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.calendar_layout,this);
NextButton = view.findViewById(R.id.nextBtn);
PreviousButton = view.findViewById(R.id.previousBtn);
CurrentDate = view.findViewById(R.id.current_Date);
gridView = view.findViewById(R.id.gridview);
}

setUpCalendar Method

The setUpCalendar method requires to create new Calendar Instance as general variable. We will use this calendar instance to move through next and previous months and cast it to the Calendar Grid Adapter. Then, we need to create new Calendar with name monthCalendar and clone the general calendar in it. Then we need to set the first day of the month of monthCalndar to day 1 and get the minus values of fist day of the week and add this values and monthCalendar DAY_OF_THE MONTH. At this point, we need to iterate through 42 cell of the GridView to add each date of month calendar in dates list.

Important note, the next code will create errors because we didn’t create the GridAdapter class. So that after copping the next code to your project, create a new Java class and name it “MyGridAdapter”.

Custom Calendar View Java File

public class CalendarCustomView extends LinearLayout {
ImageButton PreviouseButton,NextButton;
TextView CurrentDate;
GridView gridView;
private static final int MAX_CALENDAR_Days = 42;
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("MMMM yyyy", Locale.ENGLISH);
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd",Locale.ENGLISH);
SimpleDateFormat monthFormat = new SimpleDateFormat("MMMM",Locale.ENGLISH);
SimpleDateFormat yearFormat = new SimpleDateFormat("yyyy",Locale.ENGLISH);
Calendar calendar = Calendar.getInstance(Locale.ENGLISH);
Context context;
List<Events> eventsList = new ArrayList<>();
List<Date> dateList = new ArrayList<>();
DBOpenHelper dbOpenHelper;
AlertDialog alertDialog;
MyGridAdapter adapter;



public CalendarCustomView(Context context) {
super(context);
}

public CalendarCustomView(final Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
this.context=context;
IntializeUILayout();
SetupCalendar();
PreviouseButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
calendar.add(Calendar.MONTH,-1);
SetupCalendar();

}
});

NextButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
calendar.add(Calendar.MONTH,1);
SetupCalendar();
}
});
gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, final int position, long id) {

AlertDialog.Builder builder =new AlertDialog.Builder(context);
builder.setCancelable(true);
View eventView = LayoutInflater.from(parent.getContext()).inflate(R.layout.new_event_layout,null);
final EditText EventBody = eventView.findViewById(R.id.envent);
final TextView EventTime = eventView.findViewById(R.id.eventtime);
Button SelectTime = eventView.findViewById(R.id.selecttime);
Button AddEvent = eventView.findViewById(R.id.addevent);
SelectTime.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Calendar calendar = Calendar.getInstance();

final int hours =calendar.get(Calendar.HOUR_OF_DAY);
final int minuts = calendar.get(Calendar.MINUTE);

TimePickerDialog timePickerDialog;
timePickerDialog = new TimePickerDialog(getContext(),R.style.DialogTheme, new TimePickerDialog.OnTimeSetListener() {
@Override
public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
Calendar c = Calendar.getInstance();
c.set(Calendar.HOUR_OF_DAY,hourOfDay);
c.set(Calendar.MINUTE,minute);
c.setTimeZone(TimeZone.getDefault());
SimpleDateFormat format = new SimpleDateFormat("K:mm a", Locale.ENGLISH);
String PlannedTime = format.format(c.getTime());
EventTime.setText(PlannedTime);
}
},hours,minuts,false);

timePickerDialog.show();
}
});

final String date = dateFormat.format(dateList.get(position));

AddEvent.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
SaveEvent(EventBody.getText().toString(),EventTime.getText().toString(),date
,monthFormat.format(dateList.get(position)),yearFormat.format(dateList.get(position)));
SetupCalendar();
alertDialog.dismiss();

}
});


builder.setView(eventView);
alertDialog = builder.create();
alertDialog.show();






}
});

gridView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
final String date = dateFormat.format(dateList.get(position));

AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setCancelable(true);
View showView = LayoutInflater.from(parent.getContext()).inflate(R.layout.show_events_layout,null);
RecyclerView EventRV= (RecyclerView) showView.findViewById(R.id.eventsRV);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(showView.getContext());
EventRV.setLayoutManager(layoutManager);
EventRV.setHasFixedSize(true);

EventRecyclerAdapter eventRecyclerAdapter = new EventRecyclerAdapter(showView.getContext()
,CollectEvent(date));
EventRV.setAdapter(eventRecyclerAdapter);
eventRecyclerAdapter.notifyDataSetChanged();
builder.setView(showView);
alertDialog =builder.create();
alertDialog.show();

return true;
}
});

}


public CalendarCustomView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}



private ArrayList<Events> CollectEvent(String date){
ArrayList<Events> arrayList = new ArrayList<>();
dbOpenHelper = new DBOpenHelper(context);
SQLiteDatabase sqLiteDatabase = dbOpenHelper.getReadableDatabase();
Cursor cursor = dbOpenHelper.ReadEvent(date,sqLiteDatabase);
while (cursor.moveToNext()){
String event = cursor.getString(cursor.getColumnIndex(DBStructure.EVENT));
String Time = cursor.getString(cursor.getColumnIndex(DBStructure.TIME));
String Date = cursor.getString(cursor.getColumnIndex(DBStructure.DATE));
String month = cursor.getString(cursor.getColumnIndex(DBStructure.MONTH));
String year = cursor.getString(cursor.getColumnIndex(DBStructure.YEAR));
Events events = new Events(event,Time,Date,month,year);
arrayList.add(events);
}
cursor.close();
dbOpenHelper.close();
// Toast.makeText(context, String.valueOf(arrayList.size()), Toast.LENGTH_SHORT).show();

 return arrayList;
}

private void IntializeUILayout(){

LayoutInflater inflater =(LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.calendar_layout,this);
PreviouseButton = view.findViewById(R.id.previous_month);
NextButton = view.findViewById(R.id.next_month);
CurrentDate = view.findViewById(R.id.display_current_date);
gridView = view.findViewById(R.id.calendar_grid);


}

private void SetupCalendar(){
String StartDate = simpleDateFormat.format(calendar.getTime());
CurrentDate.setText(StartDate);
dateList.clear();
Calendar monthCalendar = (Calendar)calendar.clone();
monthCalendar.set(Calendar.DAY_OF_MONTH,1);
int FirstDayOfMonth = monthCalendar.get(Calendar.DAY_OF_WEEK)-1;
monthCalendar.add(Calendar.DAY_OF_MONTH,-FirstDayOfMonth);


COllectEventsPerMonth(monthFormat.format(calendar.getTime()),yearFormat.format(calendar.getTime()));


while (dateList.size() < MAX_CALENDAR_Days){
dateList.add(monthCalendar.getTime());
monthCalendar.add(Calendar.DAY_OF_MONTH,1);

}
adapter = new MyGridAdapter(context,dateList,calendar,eventsList);
gridView.setAdapter(adapter);


}

private void SaveEvent(String event,String time,String date,String Month,String Year){
dbOpenHelper = new DBOpenHelper(context);
SQLiteDatabase database = dbOpenHelper.getWritableDatabase();
dbOpenHelper.SaveEvent(event,time,date,Month,Year,database);
dbOpenHelper.close();
Toast.makeText(context, "Event Saved", Toast.LENGTH_SHORT).show();
}

private Date convertStringToDate(String dateInString){
java.text.SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd", Locale.ENGLISH);
Date date = null;
try {
date = format.parse(dateInString);

} catch (java.text.ParseException e) {
e.printStackTrace();
}
return date;
}

private void COllectEventsPerMonth(String Month,String Year){
eventsList.clear();
dbOpenHelper = new DBOpenHelper(context);
SQLiteDatabase database = dbOpenHelper.getReadableDatabase();
Cursor cursor = dbOpenHelper.ReadEventpermonth(Month,Year,database);
while (cursor.moveToNext()){
String event = cursor.getString(cursor.getColumnIndex(DBStructure.EVENT));
String Time = cursor.getString(cursor.getColumnIndex(DBStructure.TIME));
String Date = cursor.getString(cursor.getColumnIndex(DBStructure.DATE));
String month = cursor.getString(cursor.getColumnIndex(DBStructure.MONTH));
String year = cursor.getString(cursor.getColumnIndex(DBStructure.YEAR));
Events events = new Events(event,Time,Date,month,year);
eventsList.add(events);
}
}


}

MyGridAdapter Java Class

From the previous class we note that MyGridAdapter class that used in the setupCalendar Method depends on a List of Dates. This list has created by looping through the maximum calendar days (42 days). Furthermore, in each time we add in the dateList the monthCalendar Time followed by increasing the month calendar day value by one. The second dependency of the GridAdapter class is the updated calendar instance. Finally, the list of events that we collected it trough the method COllectEventsPerMonth().

public class MyGridAdapter extends ArrayAdapter {



    List<Date> dates ;
    Calendar currentDate;
    LayoutInflater inflater;
    List<Events> eventsList;

    public MyGridAdapter( Context context,List<Date> dates,Calendar currentDate,List<Events> eventsList) {
        super(context,R.layout.single_cell_layout);
        this.dates = dates;
        this.currentDate = currentDate;
        inflater = LayoutInflater.from(context);
        this.eventsList=eventsList;

    }

    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
        Date monthDate = dates.get(position);
        Calendar dateCalendar = Calendar.getInstance();
        dateCalendar.setTime(monthDate);
        int dayNo = dateCalendar.get(Calendar.DAY_OF_MONTH);
        int displayMonth = dateCalendar.get(Calendar.MONTH)+1;
        int displayYear = dateCalendar.get(Calendar.YEAR);
        int currentYear = currentDate.get(Calendar.YEAR);
        int currentMonth = currentDate.get(Calendar.MONTH)+1;




        View view = convertView;
        if(view == null){

            view = inflater.inflate(R.layout.single_cell_layout,parent,false);
        }

        if (displayMonth == currentMonth && displayYear==currentYear){
            view.setBackgroundColor(getContext().getResources().getColor(R.color.green));

        }
        else {
            view.setBackgroundColor(Color.parseColor("#cccccc"));
        }
        TextView cellNumber = view.findViewById(R.id.calendat_day);
        TextView eventText = view.findViewById(R.id.event_id);
        cellNumber.setText(String.valueOf(dayNo));
        Calendar eventCalendar = Calendar.getInstance();
                ArrayList<String> arrayList = new ArrayList<>();
        for (int i  = 0;i < eventsList.size();i++){
            eventCalendar.setTime(convertStringToDate(eventsList.get(i).getDate()));
            if(dayNo == eventCalendar.get(Calendar.DAY_OF_MONTH) && displayMonth == eventCalendar.get(Calendar.MONTH)+1
            && displayYear == eventCalendar.get(Calendar.YEAR)){
                arrayList.add(eventsList.get(i).getEvent());
                eventText.setText(arrayList.size()+" events");




            }



        }




        return view;
    }


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

    @Nullable
    @Override
    public Object getItem(int position) {
        return dates.get(position);
    }

    @Override
    public int getPosition(@Nullable Object item) {
        return dates.indexOf(item);
    }


    private Date convertStringToDate(String dateInString){
        java.text.SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd", Locale.ENGLISH);
        Date date = null;
        try {
            date = format.parse(dateInString);

        } catch (java.text.ParseException e) {
            e.printStackTrace();
        }
        return date;
    }
}

Events Recycler Adapter class

The next step, we need to show the events that we will add it in the calendar by long press method. This class is dependent on a List of Events Model. So, we first need to create a new Java class for events model the create a new one for Events Recycler Adapter.

Events Model Class:

public class Events {
    String Event, Time,Date,Month,Year;

    public Events(String event, String time, String date, String Month, String Year) {
        Event = event;
        Time = time;
        Date = date;
    }

    public String getMonth() {
        return Month;
    }

    public void setMonth(String month) {
        Month = month;
    }

    public String getYear() {
        return Year;
    }

    public void setYear(String year) {
        Year = year;
    }

    public String getEvent() {
        return Event;
    }

    public void setEvent(String event) {
        Event = event;
    }

    public String getTime() {
        return Time;
    }

    public void setTime(String time) {
        Time = time;
    }

    public String getDate() {
        return Date;
    }

    public void setDate(String date) {
        Date = date;
    }
}

Events Recycler adapter class:

public class EventRecyclerAdapter extends RecyclerView.Adapter<EventRecyclerAdapter.MyViewHolder> {
    Context context;
    ArrayList<Events> arrayList;

    public EventRecyclerAdapter(Context context, ArrayList<Events> arrayList) {
        this.context = context;
        this.arrayList = arrayList;
    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.event_rowlayout,parent,false);

        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {

        Events events = arrayList.get(position);
        holder.Event.setText(events.getEvent());
        holder.Time.setText(events.getTime());
        holder.Date.setText(events.getDate());

    }

    @Override
    public int getItemCount() {
        return arrayList.size();
    }

    public class MyViewHolder extends RecyclerView.ViewHolder{

        TextView Event,Date,Time;

        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            Event = itemView.findViewById(R.id.event);
            Date = itemView.findViewById(R.id.date);
            Time   = itemView.findViewById(R.id.eventtime);
        }
    }
}

Main Activity Java class

Finally, in main activity java class we need to initiate the custom calendar view class. Make sure that you added the custom calendar view in main activity xml layout file.

public class MainActivity extends AppCompatActivity {
    CalendarCustomView calendarCustomView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        calendarCustomView = findViewById(R.id.custom_calendar);

    }
}

after that, run your app and if your encountered errors please comment.

Thank you