How to input D.O.B and getting age using kotlin android studio?

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There is to be two activities , one activity should accept name and D.O.B and then i click the submit button which will take me to another activity where it shows the age (just the number nothing else) , the zodiac sign or picture and the birthstone. I have been trying to get the age calculated based on the date of birth but it just prints eg: 12/24/2022 , so it doesn't calculate anything. I have been trying to use a date picker dialogue but it wont show up when i click on the input space for D.O.B. Can i get some help?

What I have tried:

         private lateinit var sname: TextView
         private lateinit var sage: TextView
         private lateinit var sBstone: TextView
         private lateinit var sczodiac: TextView
         private lateinit var swelcome: TextView

        sname = findViewById(R.id.outputname)
        sage = findViewById(R.id.outputage)
        sBstone = findViewById(R.id.outputBirthstone)
        sczodiac = findViewById(R.id.outputchineseZs)
        swelcome = findViewById(R.id.Welcometext)

val bundle = intent.extras

        if (bundle != null) {
            sname.text = "Name = ${bundle.getString("name")}"
            sage.text = "Age = ${bundle.getString("dob")}"
            sBstone.text = "BirthStone = ${bundle.getString("dob")}"
            sczodiac.text = "Chinese Zodiac  = ${bundle.getString("dob")}"
            swelcome.text = "Welcome ${bundle.getString("name")}"


            // calculate and display age, birthstone, and zodiac sign here


        }

@SuppressLint("SetTextI18n")
    private fun Printage(view: View) {

        val myCalendar = Calendar.getInstance()
        val year = myCalendar.get(Calendar.YEAR)
        val month = myCalendar.get(Calendar.MONTH)
        val day = myCalendar.get(Calendar.DAY_OF_MONTH)

        DatePickerDialog(this, { datePicker, year, month, day ->

            val selectedDate = "$day/${month + 1}/$year"

            val inputDOB2 = findViewById<TextView>(R.id.InputDOB)
            inputDOB2.text = selectedDate


            val dob = Calendar.getInstance()
            dob.set(year, month, day)

            var age = myCalendar.get(Calendar.YEAR) - dob.get(Calendar.YEAR)
            if (myCalendar.get(Calendar.DAY_OF_YEAR) < dob.get(Calendar.DAY_OF_YEAR)) {
                age--
            }

            val textage = findViewById<TextView>(R.id.outputage)
            textage.text = "$sage "


        }, 2023, 5, 3).show()
    }

Kotlin

Posted 11-Feb-23 20:57pm

chilly45

Updated 13-Feb-23 1:12am

v2

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Comments

Richard MacCutchan 12-Feb-23 3:08am

The last few lines of the above code look incorrect.

            val textage = findViewById<TextView>(R.id.outputage)
            textage.text = "$sage " // this should be the age value


        }, 2023, 5, 3).show() // what is this?

chilly45 12-Feb-23 3:23am

okay so i was trying to get the date picker to show , isn't show() how it should be used to show the calendar view?
$sage is the textview for the age . wait i forgot to put something

Richard MacCutchan 12-Feb-23 3:53am

Sorry, I forgot this is Kotlin, not Java. ~~Is the 's' character in "$sage " some formatting type?~~ Actually that should be "$age ", not "$sage ", Just shows you need to take care when creating variable names.

chilly45 12-Feb-23 4:11am

i tried doing what you said , this is how it looks after, the date picker didnt show up so im not sure whats wrong, i just put it in manually
https://drive.google.com/drive/folders/1HvbgCnxgRipyB9a_ZQ-rhwJksRzdu3jb?usp=sharing

chilly45 12-Feb-23 3:58am

oh no that was just a random name so i dont get them mixed up , so your saying it should be $age in stead? okay i will try that.

Richard MacCutchan 12-Feb-23 4:30am

That is not a sensible idea. Look carefully at all the variable names in your code. Each one should be used for a specific purpose, and hold only the value assigned to it. For example you have the following code at the beginning:

            sage.text = "Age = ${bundle.getString("dob")}"
            sBstone.text = "BirthStone = ${bundle.getString("dob")}"
            sczodiac.text = "Chinese Zodiac  = ${bundle.getString("dob")}"

So all three items will contain the data of birth string.

chilly45 12-Feb-23 5:13am

i understand that part , the reason i put dob for all three of them was just to hold the space , because i still haven't coded the birthstone and chinese zodiac part but if you think thats the problem i'll try removing it.

Richard MacCutchan 12-Feb-23 7:04am

I just wanted to check that it was deliberate.

chilly45 12-Feb-23 11:14am

I tried what you said but it didn't calculate, it just outputs but this time it outputs only beside age.
https://drive.google.com/drive/folders/1HvbgCnxgRipyB9a_ZQ-rhwJksRzdu3jb?usp=sharing

Richard MacCutchan 12-Feb-23 12:23pm

Changing thos fields will not affect anything since you never use them. Try changing the code that gets the age as follows:

            var age = myCalendar.get(Calendar.YEAR) - dob.get(Calendar.YEAR)
            if (myCalendar.get(Calendar.DAY_OF_YEAR) < dob.get(Calendar.DAY_OF_YEAR)) {
                age--
            }
            // sage refers to the "outputage" field, as set at the beginning of the activity
            sage.text = "$age "

chilly45 12-Feb-23 13:30pm

// sage refers to the "outputage" field, as set at the beginning of the activity
sage.text = "$age "

I changed this but it did not do anything different?

https://drive.google.com/drive/folders/1HvbgCnxgRipyB9a_ZQ-rhwJksRzdu3jb?usp=sharing

Richard MacCutchan 13-Feb-23 3:46am

Maybe that code needs to be outside of the DatePickerDialog method.

chilly45 13-Feb-23 4:40am

it seems theres alot wrong with this code so i may have to change it but thanks for the help .

Richard MacCutchan 13-Feb-23 5:39am

Try starting with a simple activity to just get the date of birth. Once you have that working then add the code to calculate and display the age value. Keeping things simple and building up one item at a time makes it much easier to find and correct errors.

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Andre Oosthuizen · Answer 1 · 2023-02-13T01:12:00

Solution was given at Stack - Calculate age from BirthDate [^]

Using Kotlin

fun getAge(year: Int, month: Int, dayOfMonth: Int): Int {
    return Period.between(
                LocalDate.of(year, month, dayOfMonth),
                LocalDate.now()
            ).years

return getAge;
}

Imports needed to use java.time (java 8+)

import java.time.LocalDate;
import java.time.Period

There's API Desugaring now in Android, which makes (a subset of) java.time directly available (no backport library needed anymore) to API levels below 26 (not really down to version 1, but will do for most of the API levels that should be supported nowadays).

For projects supporting Java 6 or 7, this functionality is available via the ThreeTenBP [^],
while there is special version, the ThreeTenABP [^] for API levels below 26 in Android.