Stopping an app from crashing by checking if EditText is empty

Question

So i made a Calculator with 2 EditText inputs, but i couldn't stop the app from crashing when the 2 fields are empty. I found some solutions for EditText of Text type but am stuck here because i am using a Number EditText. Here is the code by the way: {

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
}
fun buPlusClick(view: View){

    var num1:Int=ednum1.text.toString().toInt()
    var num2:Int=ednum2.text.toString().toInt()
    var result = num1+num2
    val resultprint = "The result Is : $result"
    tvresult.text=resultprint
}

}

Add validation before typecasting that your ednum1 and ednum2 is not empty. — Maddy, Oct 06 '18 at 13:21
the four calculation methods are essentially identical so you only need one in the question. and it would help others if you include details of the crash — Paul D'Ambra, Oct 06 '18 at 14:25
Does this answer your question? [Unfortunately MyApp has stopped. How can I solve this?](https://stackoverflow.com/questions/23353173/unfortunately-myapp-has-stopped-how-can-i-solve-this) — Zoe, Apr 03 '21 at 19:58

score 0 · Answer 1 · answered Oct 06 '18 at 14:22

The error you're likely getting is a NumberFormatException. This is because ("" != [0-9]+) && value value !< Int.MAX_VALUE && !> Int.MIN_VALUE.

You have three options:

Check if it's empty first, as sandip mentioned.
Use toIntOrNull
Catch the exception.

toInt throws an exception (NumberFormatException) if the int is invalid. This means:

Not a number with the defined radix (default 10; an actual int. I.e. 16 is hex, but it's not applicable here)
The number is too big or too small (under Int.MIN_VALUE or over Int.MAX_VALUE).
The String is empty.

Checking if it's empty first solves half the problem; it can't be valid if it's empty. However, it doesn't solve it if there are letters or the number is too big.

You can use toIntOrNull() for this. It's just like toInt(), but it returns null if the conversion fails. You can use the elvis operator with a run block, or just use a simple if-statement to check if it's null, and handle the problems accordingly.

val num1: Int = ednum1.text.toString().toIntOrNull() ?: run {
    // Notify the user the first number is invalid
    return; // return from the method to avoid NPE's
}
val num2: Int = ednum2.text.toString().toIntOrNull() ?: run {
    // Notify the user the second number is invalid
    return;
}

if you don't understand what run does here, take a look at this question. You can also get rid of run entirely and assign a number value, just let it be null and handle it later, or something else.

The max positive value of an int is about 2.4 billion. If you expect numbers with a higher input than that, use Long, and equivalently toLongOrNull().

The last option is catching the error.

var num1: Int? = try { ednum1.text.toString().toInt() } catch (e: NumberFormatException) { 
    // You can do a lot of stuff in here; you can notify the user and `return` from the method,
    // set it to null and handle it later, or assign an integer value. 
    null 
}
var num2: Int? = try { ednum2.text.toString().toInt() } catch (e: NumberFormatException) { 
    // see my comments on the first block; same applies here
    null 
}

It is, in my opinion, slightly more bulky than toIntOrNull()( / toLongOrNull()), but it is an option.

Sandip · Answer 2 · 2018-10-06T14:03:31.180

You need to check first editText empty or not.

//Java
private boolean isEmpty(EditText editText) {

if (editText.getText().toString().trim().length() > 0) 
    return false;

return true;

}

//kotlin
private fun isEmpty(editText: EditText): Boolean {

    return if (editText.text.toString().trim { it <= ' ' }.length > 0) false else true

}

Then do the following Code:

fun buPlusClick(view: View){

if(!isEmpty(ednum1) && !isEmpty(ednum2)) {

   var num1:Int=ednum1.text.toString().toInt()
   var num2:Int=ednum2.text.toString().toInt()
   var result = num1+num2
   val resultprint = "The result Is : $result"
   tvresult.text=resultprint
 }
}

Do the above check all of your functions.

Stopping an app from crashing by checking if EditText is empty

2 Answers2