how to make a function for validating TextInputLayout kotlin - android-studio

Question

I want to make a function for validation of text inputs(material design) and use it multiple times
I have a working code but I know it is dirty
how to optimize it?
this is my onClick method
fun addItems(view: View) {
val name1 = etName.text.toString().trim()
val quantity1 = etQuantity.text.toString()
val gst1 = etGst.text.toString()
val amount1 = etAmount.text.toString()
fun showToast() {
runOnUiThread(kotlinx.coroutines.Runnable {
Toast.makeText(this, "$name1 Added", Toast.LENGTH_LONG).show()
}) // runnable is used because activity is immediately killed and toast cannot be sowed hence it is to be done on ui tread
finish()
}
if (name1.isNotBlank() && quantity1.isNotBlank() && amount1.isNotBlank()) {
if (quantity1.toInt() != 0) {
if (amount1.toInt() != 0) {
Thread {
val db = Room.databaseBuilder(this, AppDb::class.java, "BookDB")
.build()
val item = ItemEntity()
item.itemName = name1
item.quantity = quantity1
item.amount = amount1
if (boolProcessWithGST) {
if (gst1.isNotBlank()) {
if (gst1.toInt() != 0) {
// process with GST
item.gst = gst1
db.abstractItemDao().saveItems(item)
showToast()
} else runOnUiThread {
tilGST.error = "Tax can't be 0%"
etGst.requestFocus()
} // ui operation only works on main/ui thread
} else runOnUiThread {
tilGST.error = "Disable toggle if no TAX"
etGst.requestFocus()
}
} else {
// process without gst
db.abstractItemDao().saveItems(item)
showToast()
}
}.start()
} else {
tilAmount.error = "Amount can't be 0"
etAmount.requestFocus()
}
} else {
tilQuantity.error = "Quantity can't be 0"
etQuantity.requestFocus()
}
} else Toast.makeText(this, "please fill the required fields", Toast.LENGTH_LONG).show()
}
I want to use the same validation for another onClick in the same activity
I tried making a function but the android studio suggests -> Cascade if should be replaced with when. how to do so?
function I made
private fun isValidInput(): Boolean {
var isValid = true
val name1 = etName.text.toString().trim()
val quantity1 = etQuantity.text.toString()
val gst1 = etGst.text.toString()
val amount1 = etAmount.text.toString()
TransitionManager.beginDelayedTransition(root_layout)
if (name1.isEmpty()) {
tilName.isErrorEnabled = true
tilName.error = "Required"
isValid = false
} else tilName.isErrorEnabled = false
if (quantity1.isEmpty()) {
tilQuantity.isErrorEnabled = true
tilQuantity.error = "Required"
isValid = false
} else if (quantity1.toInt() == 0) {
tilQuantity.isErrorEnabled = true
tilQuantity.error = "can't be 0"
} else tilQuantity.isErrorEnabled = false
if (amount1.isEmpty()) {
tilAmount.isErrorEnabled = true
tilAmount.error = "Required"
isValid = false
}else if (amount1.toInt() == 0) {
tilAmount.isErrorEnabled = true
tilAmount.error = "can't be 0"
} else tilAmount.isErrorEnabled = false
if (gst1.isEmpty()) {
tilGST.isErrorEnabled = true
tilGST.error = "Required"
isValid = false
}else if (gst1.toInt() == 0) {
tilGST.isErrorEnabled = true
tilGST.error = "can't be 0"
} else tilGST.isErrorEnabled = false
return isValid
}

Answer 1

first I recommend using MVVM or any other architectural pattern(MVC, MVP, MVI ... ) to clean your code and achieve separation of concerns principle. in short, you should have a separate class for your application logic(in MVVM its called ViewModel) and repository class for accessing and saving your data like database or API call, and your activity is only responsible for the views. this will make your code much cleaner.
for starter, you can use this guide : Guide to app architecture
but there are tons of other resources out there which you can learn from
for your warning "Cascade if should be replaced with when" you can just hit Alt+enter and let the android studio do it for you. if it's not working you can do it yourself. it means something like this
with if:
if (num == 0) {
//do something
} else if (num < 5) {
//do something
} else {
//do something
}
convert to when looks like this:
when {
num == 0 -> {
//do something
}
num < 5 -> {
//do something
}
else -> {
//do something
}
}
when is called switch/case in other programming languages.