Translated to Kotlin

app/build.gradle

@@ -1,6 +1,7 @@
 plugins {
     id 'com.android.application'
 }
+apply plugin: 'kotlin-android'
 
 android {
     compileSdkVersion 30
@@ -25,6 +26,9 @@ android {
         sourceCompatibility JavaVersion.VERSION_1_8
         targetCompatibility JavaVersion.VERSION_1_8
     }
+    buildFeatures{
+        viewBinding true
+    }
 }
 
 dependencies {
@@ -35,4 +39,9 @@ dependencies {
     testImplementation 'junit:junit:4.+'
     androidTestImplementation 'androidx.test.ext:junit:1.1.2'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
+    implementation "androidx.core:core-ktx:+"
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+}
+repositories {
+    mavenCentral()
 }

app/src/main/AndroidManifest.xml

@@ -9,17 +9,14 @@
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/Theme.KotlinHomeWork">
-        <activity android:name=".MainActivity">
+        <activity android:name=".NewSecondActivity"></activity>
+        <activity android:name=".NewMainActivity">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
-        <activity
-            android:name=".SecondActivity"
-            android:exported="false"
-            android:windowSoftInputMode="adjustResize" />
     </application>
 
 </manifest>

app/src/main/java/com/example/kotlinhomework/NewMainActivity.kt

@@ -0,0 +1,62 @@
+package com.example.kotlinhomework
+
+import android.content.Intent
+import android.os.Bundle
+import android.os.PersistableBundle
+import android.util.Log
+import android.widget.TextView
+import androidx.appcompat.app.AppCompatActivity
+import com.example.kotlinhomework.databinding.ActivityNewMainBinding
+
+class NewMainActivity : AppCompatActivity() {
+
+    private lateinit var greetings: String
+    private lateinit var name: String
+    private lateinit var textView: TextView
+
+    private val binding: ActivityNewMainBinding by lazy {
+        val tmpBinding = ActivityNewMainBinding.inflate(layoutInflater)
+        setContentView(tmpBinding.root)
+        tmpBinding
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        greetings = getString(R.string.hello)
+        name = getString(R.string.anon)
+
+        savedInstanceState?.getString(NAME_KEY)?.let {
+            name = it
+        }
+
+        textView = binding.textViewHello
+        binding.buttonNameYourSelf.setOnClickListener {
+            startActivityForResult(Intent(this, NewSecondActivity::class.java), NewSecondActivity.GET_NAME_REQUEST_CODE)
+        }
+    }
+
+    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
+        super.onActivityResult(requestCode, resultCode, data)
+        if (requestCode == NewSecondActivity.GET_NAME_REQUEST_CODE && resultCode == RESULT_OK && data != null){
+            data.getStringExtra((NewSecondActivity.NAME_KEY))?.let{
+                name = it
+            }
+        }
+    }
+
+    override fun onResume() {
+        super.onResume()
+        textView.text = getString(R.string.format_string, greetings, name)
+    }
+
+    override fun onSaveInstanceState(outState: Bundle) {
+        super.onSaveInstanceState(outState)
+        outState.putString(NAME_KEY, name)
+    }
+
+
+    companion object {
+        const val NAME_KEY = "com.example.kotlinhomework.MainActivity.NAME_KEY"
+    }
+}

app/src/main/java/com/example/kotlinhomework/NewSecondActivity.kt

@@ -0,0 +1,63 @@
+package com.example.kotlinhomework
+
+import android.content.Intent
+import androidx.appcompat.app.AppCompatActivity
+import android.os.Bundle
+import android.text.Editable
+import android.text.TextWatcher
+import android.util.Log
+import android.widget.Button
+import android.widget.EditText
+import androidx.core.widget.addTextChangedListener
+import com.example.kotlinhomework.databinding.ActivityNewMainBinding
+import com.example.kotlinhomework.databinding.ActivityNewSecondBinding
+
+class NewSecondActivity : AppCompatActivity() {
+
+    private lateinit var editText: EditText
+    private lateinit var button: Button
+
+    private val binding: ActivityNewSecondBinding by lazy {
+        val tmpBinding = ActivityNewSecondBinding.inflate(layoutInflater)
+        setContentView(tmpBinding.root)
+        tmpBinding
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        editText = binding.editTextTextPersonName
+        button = binding.buttonName
+        button.isEnabled = false
+        editText.addTextChangedListener(object : TextWatcher{
+            override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
+                // Nothing to do
+            }
+
+            override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
+                // Nothing to do
+            }
+
+            override fun afterTextChanged(s: Editable?) {
+                s?.let {
+                    if(it.isNotEmpty()) button.isEnabled = true
+                }
+
+            }
+
+        })
+
+        button.setOnClickListener {
+            val intent = Intent().apply {
+                putExtra(NAME_KEY, editText.text.toString())
+            }
+            setResult(RESULT_OK, intent)
+            finish()
+        }
+    }
+
+    companion object {
+        const val NAME_KEY = "com.example.kotlinhomework.SecondActivity.NAME_KEY"
+        const val GET_NAME_REQUEST_CODE = 1234
+    }
+}

app/src/main/res/layout/activity_main.xml → app/src/main/res/layout/activity_new_main.xml

@@ -3,8 +3,7 @@
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    tools:context=".MainActivity">
+    android:layout_height="match_parent">
 
     <TextView
         android:id="@+id/textViewHello"

app/src/main/res/values/strings.xml

@@ -5,4 +5,5 @@
     <string name="anon">Anon</string>
     <string name="enter_name">Enter your name</string>
     <string name="my_name">That\'s my name!</string>
+    <string name="format_string">%s, %s!</string>
 </resources>

build.gradle

@@ -1,11 +1,13 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 buildscript {
+    ext.kotlin_version = '1.4.21'
     repositories {
         google()
         jcenter()
     }
     dependencies {
         classpath "com.android.tools.build:gradle:7.0.0-alpha02"
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files