Day41 of #100DaysOfCode

#CodeTogether Day 41/100

Hii folks 🙌

Today I completed pathway 1 of Unit 2 of the Android Basic with Kotlin.

Unit 2: Layouts

Pathway 1: Get user input in an app — Part 1

Source: https://developer.android.com/courses/android-basics-kotlin/course

Today my task was to write down the function for my android app to calculate the tip, assessing all the UI components of the app.

So, the android provides a feature called view binding. With a little more work upfront, view binding makes it much easier and faster to call methods on the views in our UI.

So, in the build.gradle file I enabled the viewBinding feature.

buildFeatures {
    viewBinding true
}

Then in the MainActivity.kt initialized the binding object.

class MainActivity : AppCompatActivity() {

    lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)
    }
}

This line initializes the binding object.

binding = ActivityMainBinding.inflate(layoutInflater)

Now, I wrote the function calculateTip() which will calculate the tip as per the user input.

fun calculateTip() {
    val stringInTextField = binding.costOfService.text.toString()
    val cost = stringInTextField.toDouble()
    val selectedId = binding.tipOptions.checkedRadioButtonId
    val tipPercentage = when (selectedId) {
        R.id.option_twenty_percent -> 0.20
        R.id.option_eighteen_percent -> 0.18
        else -> 0.15
    }
    var tip = tipPercentage * cost
    val roundUp = binding.roundUpSwitch.isChecked
    if (roundUp) {
        tip = kotlin.math.ceil(tip)
    }
    val formattedTip = NumberFormat.getCurrencyInstance().format(tip)
    binding.tipResult.text = getString(R.string.tip_amount, formattedTip)
}

TipTime

Now the app looks something like this which calculates the tip as per the user’s input. It was fun building one.

Today I Learned:

• View binding lets us more easily write code that interacts with the UI elements in our app
• Use the checkedRadioButtonId attribute of a RadioGroup to find which RadioButton is selected.
• Use NumberFormat.getCurrencyInstance() to get a formatter to use for formatting numbers as currency.
• We can use string parameters like%s to create dynamic strings that can still be easily translated into other languages.
• We can use Logcat in Android Studio to troubleshoot problems like the app crashing.
• Exceptions indicate a problem that the code didn’t expect.
• Not all code can handle null values, so be careful using it.

That is all for Day41 ✅

Thanks for reading, See you tomorrow!