temp converter (.kt)

MainActivity.kt

import android.content.ClipData
import android.content.ClipboardManager
import android.content.Context
import android.os.Bundle
import android.support.v7.app.AppCompatActivity;
import android.text.Editable
import android.text.TextWatcher
import android.view.View

import kotlinx.android.synthetic.main.activity_main.*
import kotlinx.android.synthetic.main.content_main.*
import java.util.*
import android.content.Intent

class MainActivity : AppCompatActivity(), TextWatcher, View.OnFocusChangeListener {

    override fun onFocusChange(v: View?, hasFocus: Boolean) {
        when {
            hasFocus -> when (v) {
                fahrenheit -> {
                    celsius.removeTextChangedListener(this)
                    fahrenheit.addTextChangedListener(this)
                }
                celsius -> {
                    fahrenheit.removeTextChangedListener(this)
                    celsius.addTextChangedListener(this)
                }
            }
        }
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        setSupportActionBar(toolbar)

        supportActionBar?.hide()

        celsius.onFocusChangeListener = this
        fahrenheit.onFocusChangeListener = this

        copy.setOnClickListener { copy() }
        share.setOnClickListener { share() }
        clear.setOnClickListener {
            celsius.setText("")
            fahrenheit.setText("")
        }
    }

    override fun afterTextChanged(s: Editable?) {}
    override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}
    override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
        val str = s.toString()
        try {
            when {
                celsius.hasFocus() -> if (str.isNotEmpty()) {
                    fahrenheit.setText(String.format(Locale.getDefault(), "%.1f", (str.toDouble() * 1.8000) + 32.0))
                } else fahrenheit.setText("")
                else -> if (str.isNotEmpty()) {
                    celsius.setText(String.format(Locale.getDefault(), "%.1f", ((str.toDouble() - 32.0) * 5.0) / 9.0))
                } else celsius.setText("")
            }
        } catch (e: Exception) {
            e.printStackTrace()
        }
    }

    private fun copy() {
        when {
            hasValues() -> {
                val manager = getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
                val clip = ClipData.newPlainText("text", buildSharableText())
                manager.primaryClip = clip
            }
        }
    }

    private fun share() {
        when {
            hasValues() -> {
                val i = Intent()
                i.apply {
                    action = Intent.ACTION_SEND
                    putExtra(Intent.EXTRA_TEXT, buildSharableText())
                    type = "text/plain"
                }
                startActivity(Intent.createChooser(i,"share to..."))
            }
        }
    }

    private fun hasValues(): Boolean = celsius.text.isNotEmpty() && fahrenheit.text.isNotEmpty()
    
    private fun buildSharableText(): String = String.format(Locale.getDefault(), "%.1f°C = %.1f°F", celsius.text.toString().toDouble(), fahrenheit.text.toString().toDouble())
}