RadioButtons are uncheckable after answering

app/build.gradle

@@ -9,7 +9,7 @@ android {
     buildToolsVersion "29.0.2"
     defaultConfig {
         applicationId "com.example.quickmax"
-        minSdkVersion 17
+        minSdkVersion 21
         targetSdkVersion 29
         versionCode 1
         versionName "1.0"
@@ -30,8 +30,10 @@ dependencies {
     implementation 'androidx.appcompat:appcompat:1.1.0'
     implementation 'androidx.core:core-ktx:1.1.0'
     implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
+    implementation 'com.google.android.material:material:1.0.0'
+
     testImplementation 'junit:junit:4.12'
     androidTestImplementation 'androidx.test:runner:1.2.0'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
-    androidTestImplementation 'com.android.support.test:rules:1.0.2'
+    androidTestImplementation 'androidx.test:rules:1.2.0'
 }

app/src/androidTest/java/com/example/quickmax/MainActivityTest.kt

@@ -67,7 +67,7 @@ class MainActivityTest {
 
     @Test
     fun fragment_when_time_is_over() {
-        Thread.sleep(3000)
+        Thread.sleep(4000)
         assertNotNull(testRule.activity.supportFragmentManager.fragments.find {
                 f -> f is TimeIsOverFragment })
     }

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

@@ -5,30 +5,29 @@ import android.os.CountDownTimer
 import android.view.View
 import android.widget.RadioButton
 import androidx.appcompat.app.AppCompatActivity
+import androidx.core.view.get
 import androidx.fragment.app.Fragment
 import kotlinx.android.synthetic.main.activity_main.*
 
 class MainActivity : AppCompatActivity() {
 
     var numberSet = NumberSet(4, 3)
-    private var toAcceptAnswer = true
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
-
         addRadioButtons()
         setTimer()
     }
 
     private fun setTimer() {
-        object : CountDownTimer(3000, 1000) {
-
+        object : CountDownTimer(4000, 1000) {
             override fun onTick(millisUntilFinished: Long) {
                 tv_time_left.text = (millisUntilFinished / 1000).toString()
             }
 
             override fun onFinish() {
+                makeRadioButtonsUncheckable()
                 supportFragmentManager
                     .beginTransaction()
                     .add(R.id.main_layout, TimeIsOverFragment.newInstance(), "time_is_over")
@@ -48,9 +47,6 @@ class MainActivity : AppCompatActivity() {
     }
 
     private fun processAnswer(answer: Int) {
-        if (!toAcceptAnswer)
-            return
-        toAcceptAnswer = false
         val responseFragment: Fragment = if (numberSet.isCorrect(answer)) {
             ResponseCorrectFragment.newInstance()
         } else
@@ -60,5 +56,12 @@ class MainActivity : AppCompatActivity() {
             .beginTransaction()
             .add(R.id.main_layout, responseFragment, "response")
             .commitAllowingStateLoss()
+        makeRadioButtonsUncheckable()
+    }
+
+    private fun makeRadioButtonsUncheckable() {
+        for (i in 0 until radio_group.childCount) {
+            radio_group[i].isClickable = false
+        }
     }
 }

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

@@ -2,16 +2,32 @@
 <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
-    android:layout_height="match_parent">
+    android:layout_height="match_parent"
+    android:background="#A80C0000">
 
     <ImageView
         android:id="@+id/imageView"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
+        android:layout_marginBottom="8dp"
         android:tint="#F44336"
-        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintBottom_toTopOf="@id/textView"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintVertical_chainStyle="packed"
         app:srcCompat="@drawable/ic_timer_big" />
+
+    <TextView
+        android:id="@+id/textView"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="8dp"
+        android:text="@string/time_is_over"
+        android:textAppearance="@android:style/TextAppearance.Material.Large"
+        android:textColor="#F44336"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/imageView" />
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file

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

@@ -3,4 +3,5 @@
     <string name="second_max">Выберите второе наибольшее число</string>
     <string name="response_correct">CORRECT</string>
     <string name="response_wrong">WRONG</string>
+    <string name="time_is_over">TIME IS OVER</string>
 </resources>