Переписать Java на Kotlin

app/src/main/AndroidManifest.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
     package="com.example.kotlinhomework">
 
     <application
@@ -19,7 +20,8 @@
         <activity
             android:name=".SecondActivity"
             android:exported="false"
-            android:windowSoftInputMode="adjustResize" />
+            android:windowSoftInputMode="adjustResize"
+            tools:ignore="Instantiatable" />
     </application>
 
 </manifest>

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

@@ -0,0 +1,62 @@
+package com.example.kotlinhomework
+
+import android.content.Intent
+import android.os.Bundle
+import android.widget.Button
+import android.widget.TextView
+import androidx.annotation.NonNull
+import androidx.annotation.Nullable
+import androidx.appcompat.app.AppCompatActivity
+import com.example.kotlinhomework.SecondActivityJava.NAME_KEY
+
+class MainActivity: AppCompatActivity() {
+    private var greetings: String? = null;
+    private var name: String? = null;
+    private var textView: TextView? = null;
+
+    override fun onCreate(savedInstanceState: Bundle?){
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_main)
+
+        greetings = getString(R.string.hello)
+        if (savedInstanceState != null && savedInstanceState.getString(NAME_KEY) != null) {
+            name = savedInstanceState.getString(NAME_KEY)
+        } else {
+            name = getString(R.string.anon);
+        }
+        textView = findViewById(R.id.textViewHello)
+        val button = findViewById<Button>(R.id.buttonNameYourSelf)
+        /*button.setOnClickListener {
+            val intent = Intent(this@MainActivity, SecondActivity.class)
+            startActivityForResult(intent, SecondActivityJava.GET_NAME_REQUEST_CODE)
+        }*/
+    }
+
+    override protected fun onActivityResult(requestCode: Int, resultCode: Int, @Nullable data: Intent?) {
+        super.onActivityResult(requestCode, resultCode, data)
+
+        if (requestCode == SecondActivity.GET_NAME_REQUEST_CODE && resultCode == RESULT_OK && data != null) {
+            val nameFromData = data!!.getStringExtra(SecondActivity.NAME_KEY)
+
+            if (nameFromData != null) {
+                name = nameFromData
+            }
+        }
+    }
+
+    override protected fun onResume() {
+        super.onResume()
+        textView!!.setText("${greetings}, ${name}!")
+    }
+
+    override protected fun onSaveInstanceState(@NonNull outState: Bundle) {
+        super.onSaveInstanceState(outState)
+        outState.putString(NAME_KEY, name)
+    }
+
+    companion object {
+        private val NAME_KEY = "com.example.kotlinhomework.MainActivity.NAME_KEY"
+    }
+
+
+}

app/src/main/java/com/example/kotlinhomework/MainActivity.java → app/src/main/java/com/example/kotlinhomework/MainActivityJava.java

@@ -10,7 +10,7 @@
 import androidx.annotation.Nullable;
 import androidx.appcompat.app.AppCompatActivity;
 
-public class MainActivity extends AppCompatActivity {
+public class MainActivityJava extends AppCompatActivity {
 
     private String greetings;
     private String name;
@@ -34,8 +34,8 @@ protected void onCreate(Bundle savedInstanceState) {
         button.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View view) {
-                Intent intent = new Intent(MainActivity.this, SecondActivity.class);
-                startActivityForResult(intent, SecondActivity.GET_NAME_REQUEST_CODE);
+                Intent intent = new Intent(MainActivityJava.this, SecondActivityJava.class);
+                startActivityForResult(intent, SecondActivityJava.GET_NAME_REQUEST_CODE);
             }
         });
     }
@@ -44,8 +44,8 @@ public void onClick(View view) {
     protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
         super.onActivityResult(requestCode, resultCode, data);
 
-        if (requestCode == SecondActivity.GET_NAME_REQUEST_CODE && resultCode == RESULT_OK && data != null) {
-            String nameFromData = data.getStringExtra(SecondActivity.NAME_KEY);
+        if (requestCode == SecondActivityJava.GET_NAME_REQUEST_CODE && resultCode == RESULT_OK && data != null) {
+            String nameFromData = data.getStringExtra(SecondActivityJava.NAME_KEY);
 
             if (nameFromData != null) {
                 name = nameFromData;

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

@@ -0,0 +1,57 @@
+package com.example.kotlinhomework
+
+import android.content.Intent
+import android.os.Bundle
+import android.text.Editable
+import android.text.TextUtils
+import android.text.TextWatcher
+import android.view.View
+import android.widget.Button
+import android.widget.EditText
+
+import androidx.appcompat.app.AppCompatActivity
+
+class SecondActivity : AppCompatActivity() {
+
+    private var editText: EditText? = null
+    private var button: Button? = null
+
+    override protected fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_second)
+
+        editText = findViewById(R.id.editTextTextPersonName)
+        button = findViewById(R.id.buttonName)
+        button!!.setEnabled(false)
+        editText!!.addTextChangedListener(object : TextWatcher {
+
+            override fun beforeTextChanged(charSequence: CharSequence, i: Int, i1: Int, i2: Int) {
+                // Nothing to do
+            }
+
+            override fun onTextChanged(charSequence: CharSequence, i: Int, i1: Int, i2: Int) {
+                // Nothing to do
+            }
+
+            override fun afterTextChanged(editable: Editable) {
+                button!!.setEnabled(!TextUtils.isEmpty(editable))
+            }
+
+        })
+        button!!.setOnClickListener(object : View.OnClickListener {
+
+            override fun onClick(view: View) {
+                val intent = Intent()
+                intent.putExtra(NAME_KEY, editText!!.getText().toString())
+                setResult(RESULT_OK, intent)
+                finish()
+            }
+        })
+    }
+
+    companion object {
+
+        val NAME_KEY = "com.example.kotlinhomework.SecondActivity.NAME_KEY"
+        val GET_NAME_REQUEST_CODE = 1234
+    }
+}

app/src/main/java/com/example/kotlinhomework/SecondActivity.java → app/src/main/java/com/example/kotlinhomework/SecondActivityJava.java

@@ -11,7 +11,7 @@
 
 import androidx.appcompat.app.AppCompatActivity;
 
-public class SecondActivity extends AppCompatActivity {
+public class SecondActivityJava extends AppCompatActivity {
 
     private EditText editText;
     private Button button;

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

@@ -4,7 +4,7 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    tools:context=".MainActivity">
+    tools:context=".MainActivityJava">
 
     <TextView
         android:id="@+id/textViewHello"