Age calculator project in Android and Kotlin.

You can create your own xml file to design you application,

so I am not giving here the xml file. But you can access the

whole project from my Github account. link is given below.

3:  import android.app.DatePickerDialog  
4:  import android.os.Bundle  
5:  import android.util.Log  
6:  import androidx.appcompat.app.AppCompatActivity  
7:  import kotlinx.android.synthetic.main.activity_main.*  
8:  import java.text.SimpleDateFormat  
9:  import java.time.LocalDate  
10:  import java.util.*  
11:    
12:  class MainActivity : AppCompatActivity() {  
13:    lateinit var selected_date: Date  
14:    lateinit var yourAge: String  
15:    lateinit var date_formater: SimpleDateFormat  
16:    override fun onCreate(savedInstanceState: Bundle?) {  
17:      super.onCreate(savedInstanceState)  
18:      setContentView(R.layout.activity_main)  
19:      date_formater = SimpleDateFormat("dd/MM/yyyy") // It will change the date into a string buffer in this pattern  
20:      val today_date = date_formater.format(Date()) // format function took a date as a argument and Date() is function which returns today's date  
21:      showing_today_date.setText(today_date)  
22:      click_to_show_cal.setOnClickListener{  
23:        Opendatepicker()  
24:      }  
25:      calculateBtn.setOnClickListener {  
26:        showing_your_age.setText(yourAge) // Showing the age of person after clicking the calculate button  
27:      }  
28:    }  
29:    @Suppress("DEPRECATION")  
30:    fun Opendatepicker() {  
31:      val cal = Calendar.getInstance() // Creating a calendar instance to open a calendar form your phone  
32:      val date = cal.time  
33:      val year = date.year  
34:      val month = date.month  
35:      val day = date.day  
36:      DatePickerDialog(this, DatePickerDialog.OnDateSetListener { View, selectYear, selectMonth, selectDay ->  
37:        selected_date = Date(selectYear - 1900, selectMonth, selectDay)  
38:        val show_date = date_formater.format(selected_date)  
39:        showing_selected_date.setText(show_date)  
40:        this.yourAge = claculate(selectYear, selectMonth, selectDay)  
41:        // calculate is a function which return a string which is shown as a string, top of the your age. created below  
42:      }, year, month, day).show() // In this line the year, month and day are the same as line 33, 34 and 35  
43:    }  
44:    fun claculate(selected_year: Int, selected_month: Int, selected_day: Int): String {  
45:      val date_today = LocalDate.now()  
46:      val todayDay = date_today.dayOfMonth  
47:      val todayMonth = date_today.monthValue  
48:      val todayYear = date_today.year  
49:      var age_year:Int  
50:      var age_month:Int  
51:      var age_day:Int  
52:    
53:      //Logic to find age and after calculating returning the string  
54:      if (todayYear > selected_year) {  
55:        if ((todayMonth >= selected_month) && (todayDay >= selected_day)) {  
56:          age_year = todayYear - selected_year  
57:          age_month = todayMonth - (selected_month+1)  
58:          age_day = todayDay - selected_day  
59:        } else if (todayMonth < selected_month && todayDay < selected_day) {  
60:          age_year = (todayYear-1) - selected_year  
61:          age_month = ((todayMonth + 12)-1) - (selected_month+1)  
62:          age_day = (todayDay + 30) - selected_day  
63:        } else if (todayMonth < selected_month) {  
64:          age_year = (todayYear-1) - selected_year  
65:          age_month = (todayMonth + 12) - (selected_month+1)  
66:          age_day = todayDay - selected_day  
67:        } else if (todayDay < selected_day) {  
68:          age_year = todayYear - selected_year  
69:          age_month = (todayMonth -1) - (selected_month+1)  
70:          age_day = (todayDay + 30) - selected_day  
71:        } else {  
72:          return "You Entered Wrong Date"  
73:        }  
74:        return "$age_year Years, $age_month Months, $age_day Days"  
75:      } else {  
76:        return "You have not born yet"  
77:      }  
78:    }  
79:  }  
80:    

Github Link is Here.

Apk file is uploaded on github also.