I'm new to Kotlin but there is enough overlap between Kotlin and the previous language Android used (a weird mix of mangled Java and XML) that recognize what I'm doing. I got this error
```java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.durationv1/com.example.durationv1.MainActivity}:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference```
when I ran the following code (which did not start at all):
import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import androidx.constraintlayout.widget.ConstraintLayout
import java.time.LocalDate
import java.time.Period
import java.time.format.DateTimeFormatter
class MainActivity : AppCompatActivity() {
var date1: EditText = findViewById(R.id.TextDate1)
var date2: EditText = findViewById(R.id.TextDate2)
var dateButton: Button = findViewById(R.id.GetDateLength)
val constraintLayout:ConstraintLayout = findViewById(R.id.constraintLayout)
val DateLengthtv:TextView = findViewById(R.id.displayDateLength)
var textDate1 = date1.getText().toString().trim()
var textDate2 = date2.getText().toString().trim()
var td1: LocalDate = LocalDate.parse(textDate1, DateTimeFormatter.ofPattern("mm/dd/yyyy"))
var td2: LocalDate = LocalDate.parse(textDate2, DateTimeFormatter.ofPattern("mm/dd/yyyy"))
val period: Period = Period.between(td1, td2)
var daysbetween: Int = period.days
var monthsbetween: Int = period.months
var yearsbetween: Int = period.years
//var dateString1: Period = "The time Between these days is: $yearsbetween, $monthsbetween, $daysbetween"
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
constraintLayout.setBackgroundColor(Color.GREEN)
dateButton.setOnClickListener {DateLengthtv.setText(R.string.datedisplaylength)}
}
}```
The code is supposed to show two edittext boxes that let the user choose two dates and a button that, when pressed, shows the length of time between the user's chosen dates.
I expected two editText boxes, a textview box, and a button. Instead, the program didn't make it past starting the emulator. I know the error has something to do with Context, but I am not entirely sure what. Context appeared as part of the prewritten code when I ran programs in the past with Java but it did not appear for Kotlin. Was I supposed to add it myself? If so, where? And what should it be doing?
