Update. Add language setting.

app/src/main/java/me/zobrist/tichucounter/ContextUtils.kt

@@ -0,0 +1,34 @@
+package me.zobrist.tichucounter
+
+import android.content.Context
+import android.content.ContextWrapper
+import android.content.res.Configuration
+import android.content.res.Resources
+import android.os.Build
+import android.os.LocaleList
+import java.util.*
+
+class ContextUtils(base: Context) : ContextWrapper(base) {
+
+    companion object {
+
+        fun updateLocale(c: Context, localeToSwitchTo: Locale): ContextWrapper {
+            var context = c
+            val resources: Resources = context.resources
+            val configuration: Configuration = resources.configuration
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
+                val localeList = LocaleList(localeToSwitchTo)
+                LocaleList.setDefault(localeList)
+                configuration.setLocales(localeList)
+            } else {
+                configuration.locale = localeToSwitchTo
+            }
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N_MR1) {
+                context = context.createConfigurationContext(configuration)
+            } else {
+                resources.updateConfiguration(configuration, resources.displayMetrics)
+            }
+            return ContextUtils(context)
+        }
+    }
+}

app/src/main/java/me/zobrist/tichucounter/MainActivity.kt

@@ -2,6 +2,8 @@ package me.zobrist.tichucounter
 
 import android.app.AlertDialog
 import android.content.Context
+import android.content.ContextWrapper
+import android.content.Intent
 import android.os.Bundle
 import android.text.InputType
 import android.view.Menu
@@ -14,6 +16,7 @@ import androidx.appcompat.app.AppCompatDelegate
 import androidx.core.widget.doOnTextChanged
 import com.google.gson.Gson
 import kotlinx.android.synthetic.main.content_main.*
+import java.util.*
 
 class MainActivity : AppCompatActivity() {
 
@@ -21,6 +24,15 @@ class MainActivity : AppCompatActivity() {
 
     private lateinit var history: History
     private var currentRound = Round()
+    private var systemLocale = Locale.getDefault()
+
+    override fun attachBaseContext(newBase: Context) {
+        // get chosen language from shread preference
+        val localeString = newBase.getSharedPreferences("Settings", Context.MODE_PRIVATE).getString("Language", systemLocale.toString())
+        val localeToSwitchTo = Locale(localeString)
+        val localeUpdatedContext: ContextWrapper = ContextUtils.updateLocale(newBase, localeToSwitchTo)
+        super.attachBaseContext(localeUpdatedContext)
+    }
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -36,26 +48,32 @@ class MainActivity : AppCompatActivity() {
                 .getBoolean("Screen_On", false)
         )
 
+
         val json = this.getSharedPreferences("Settings", Context.MODE_PRIVATE).getString("history", "{\"scores\":[]}")
         history = Gson().fromJson(json, History::class.java)
         nameTeamA.setText(this.getSharedPreferences("Settings", Context.MODE_PRIVATE).getString("nameTeamA", "TeamA"))
         nameTeamB.setText(this.getSharedPreferences("Settings", Context.MODE_PRIVATE).getString("nameTeamB", "TeamB"))
         updateView()
 
+        this.setListenes()
 
-        inputTeamA.setOnFocusChangeListener { view, b ->
+    }
+
+    private fun setListenes()
+    {
+        inputTeamA.setOnFocusChangeListener { _, b ->
             if (b) {
                 hideKeyboard()
             }
         }
 
-        inputTeamB.setOnFocusChangeListener { view, b ->
+        inputTeamB.setOnFocusChangeListener { _, b ->
             if (b) {
                 hideKeyboard()
             }
         }
 
-        inputTeamA.doOnTextChanged { text, start, count, after ->
+        inputTeamA.doOnTextChanged { text, _, _, _ ->
             if (inputTeamA.isFocused) {
                 if (inputTeamA.text.isNotEmpty()) {
                     if (updateOnChange) {
@@ -82,9 +100,7 @@ class MainActivity : AppCompatActivity() {
             }
         }
 
-
-
-        inputTeamB.doOnTextChanged { text, start, count, after ->
+        inputTeamB.doOnTextChanged { text, _, _, _ ->
             if (inputTeamB.isFocused) {
                 if (inputTeamB.text.isNotEmpty()) {
                     if (updateOnChange) {
@@ -323,11 +339,11 @@ class MainActivity : AppCompatActivity() {
                 builder.setMessage(getString(R.string.confirmClear))
                     .setTitle(R.string.clear)
                     .setCancelable(false)
-                    .setPositiveButton(getString(R.string.yes)) { dialog, id ->
+                    .setPositiveButton(getString(R.string.yes)) { dialog, _ ->
                         dialog.dismiss()
                         clearAll()
                     }
-                    .setNegativeButton(getString(R.string.no)) { dialog, id ->
+                    .setNegativeButton(getString(R.string.no)) { dialog, _ ->
                         dialog.cancel()
                     }
 
@@ -342,6 +358,10 @@ class MainActivity : AppCompatActivity() {
                 chooseThemeDialog()
                 true
             }
+            R.id.action_language -> {
+                chooseLanguageDialog()
+                true
+            }
             R.id.action_screenOn -> {
                 item.isChecked = !item.isChecked
                 keepScreenOn(item.isChecked)
@@ -409,7 +429,7 @@ class MainActivity : AppCompatActivity() {
 
         val builder = AlertDialog.Builder(this)
         builder.setTitle(getString(R.string.choose_theme_text))
-        val styles = arrayOf("Light", "Dark", "System default")
+        val styles = arrayOf(getString(R.string.light), getString(R.string.dark), getString(R.string.android_default_text))
 
         val checkedItem =
             this.getSharedPreferences("Settings", Context.MODE_PRIVATE).getInt("Theme", 2)
@@ -431,6 +451,42 @@ class MainActivity : AppCompatActivity() {
         dialog.show()
     }
 
+    private fun chooseLanguageDialog() {
+
+        val builder = AlertDialog.Builder(this)
+        builder.setTitle(getString(R.string.choose_language_text))
+
+        val languages_map = mapOf(
+            getString(R.string.android_default_text) to systemLocale.toString(),
+            getString(R.string.english) to "en",
+            getString(R.string.german) to "de")
+
+        val languages_display_keys = languages_map.keys.toTypedArray()
+        val languages_display_values = languages_map.values.toTypedArray()
+
+
+        val checkedItem = this.getSharedPreferences("Settings", Context.MODE_PRIVATE).getString("Language", R.string.android_default_text.toString())
+        val checkedItemIndex = languages_display_values.indexOf(checkedItem)
+
+        val prefs = this.getSharedPreferences("Settings", Context.MODE_PRIVATE).edit()
+
+
+        builder.setSingleChoiceItems(languages_display_keys, checkedItemIndex) { dialog, which ->
+
+            val temp = languages_map[languages_display_keys[which]]
+            prefs.putString("Language", temp)
+            prefs.apply()
+
+            startActivity(Intent(this, MainActivity::class.java))
+            finish()
+
+            dialog.dismiss()
+        }
+
+        val dialog = builder.create()
+        dialog.show()
+    }
+
     private fun updateTheme(which: Int) {
         when (which) {
             0 -> AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO)