FATAL EXCEPTION: main KotlinNullPointerException

3
votes

This is my first time building an android application. However when i run the app on my Virtual Device, it stopped working and keeps crashing. The error says something about null pointer exception. This is my first time using Kotlin and I coded in Java and changed to Kotlin.

 override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_add_sales)

    val date: EditText? = null
    val changeDate: CheckBox? = null
    val yes: RadioButton? = null
    val no: RadioButton? = null

    date!!.setText("15-11-2017")
    date.isEnabled = false

    val button2 = findViewById<View>(R.id.btnSubmit) as Button
    button2.setOnClickListener {
        var name = findViewById<View>(R.id.name) as EditText
        var cost = findViewById<View>(R.id.cost) as EditText
        val itemcost = Integer.parseInt(cost!!.text.toString())
        var price = findViewById<View>(R.id.price) as EditText
        val itemprice = Integer.parseInt(price!!.text.toString())
        var qty = findViewById<View>(R.id.quantity) as EditText
        var chgDate = false
        var discount = false
        val toast = Toast(applicationContext)
        if (itemprice < itemcost) {
            price!!.error = "Selling price cannot be lower than item price!"
        } else {
            if (changeDate!!.isChecked) {
                chgDate = true
                date.isEnabled = true
            }
            if (yes!!.isChecked) {
                discount = true
            }
        }
        Toast.makeText(this@AddSales, "Item Name: " + name!!.text + "\n" + "Cost: " + cost!!.text + "\n" + "Item Price: " + price!!.text + "\n" + "Quantity: " + qty!!.text + "Date: " + date + "Staff Discount: " + discount, Toast.LENGTH_SHORT).show()
    }

}

and the error is:

11-17 06:23:34.603 3540-3540/com.example.ruiru.salestracker E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.ruiru.salestracker, PID: 3540 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ruiru.salestracker/com.example.ruiru.salestracker.AddSales}: kotlin.KotlinNullPointerException at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2817) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892) at android.app.ActivityThread.-wrap11(Unknown Source:0) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593) at android.os.Handler.dispatchMessage(Handler.java:105) at android.os.Looper.loop(Looper.java:164) at android.app.ActivityThread.main(ActivityThread.java:6541) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767) Caused by: kotlin.KotlinNullPointerException at com.example.ruiru.salestracker.AddSales.onCreate(AddSales.kt:25) at android.app.Activity.performCreate(Activity.java:6975) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)  at android.app.ActivityThread.-wrap11(Unknown Source:0)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)  at android.os.Handler.dispatchMessage(Handler.java:105)  at android.os.Looper.loop(Looper.java:164)  at android.app.ActivityThread.main(ActivityThread.java:6541)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

4
androidkotlin
date!!.setText("15-11-2017") date you declared as null. and you are setting text to null variable. Set text after initialise the view date. – MathanG

4 Answers

0
votes

It seems like you forgot to initialize date editText. Why not to try Kotlin Android Extension plugin. By using this plugin you don't need to initialize the views instead you can directly use them using their id. For your case: Just add import

import kotlinx.android.synthetic.main.activity_add_sales.*

Then you can now remove your: 

val date: EditText? = null
val changeDate: CheckBox? = null
val yes: RadioButton? = null
val no: RadioButton? = null

and you can access them by their ids. like

date.setText("15-11-2017")
1
votes

Because your date EditText is null.Before use editText initialise editText like this

var date = findViewById<View>(R.id.date) as? EditText

then set the value of date

date?.setText("15-11-2017")
date?.isEnabled = false
1
votes

Your EditText is null. You can initialize your EditText. Example Kotlin code,

 override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_add_sales)

    val date = findViewById<EditText>(R.id.editTextDate)
    date.apply {
        setText("15-11-2017")
        isEnabled = false
    }
  }
0
votes
val date: EditText? = null
val changeDate: CheckBox? = null
val yes: RadioButton? = null
val no: RadioButton? = null

Before using these variables, initialize them with findViewById or bind them to the xml view.