guuilp

public class MainActivity extends AppCompatActivity {

    private CardView cardView;
    private Boolean isCollapsed = true;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

guuilp

class PeopleActivity : AppCompatActivity() {

    private val people = listOf(
        Person(1, "Person 1", "Brazil"),
        Person(2, "Person 2", "USA"),
        Person(3, "Person 3", "Canada"),
        Person(4, "Person 4", "Russia"),
        Person(5, "Person 5", "Germany")
    )

guuilp

class PeopleAdapter(private val people: List<Person>, private val listener: Listener) :
    RecyclerView.Adapter<PeopleAdapter.ViewHolder>() {

    private var selectedPerson: Person? = null

    interface Listener {
        fun onItemClicked(person: Person)
    }

    fun updateSelectedPerson(person: Person) {

guuilp

override fun onBindViewHolder(holder: ViewHolder, position: Int) {
    holder.apply {
        checkBox.isChecked = position == mCheckedPosition
        checkBox.setOnClickListener { 
            if(position == mCheckedPosition) {
                checkBox.isChecked = false
                mCheckedPosition = -1
            } else {
                mCheckedPosition = position
                notifyDataSetChanged()

guuilp

class PeopleViewModel : ViewModel() {
    private val selectedPerson = MutableLiveData<Person>()

    fun setSelectedPerson(person: Person){
        selectedPerson.value = person
    }

    fun getSelectedPerson() = selectedPerson
}

guuilp

<android.support.constraint.Group
    android:id="@+id/group_retweet"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:constraint_referenced_ids="retweet_top, retweet_user"/>

guuilp

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    tools:context=".MainActivity"
    android:background="@color/mirage"
    android:padding="16dp">

guuilp

<ImageView
    android:id="@+id/comment"
    android:layout_width="21dp"
    android:layout_height="21dp"
    android:layout_marginTop="12dp"

    android:src="@drawable/ic_comment"
    android:tint="@color/gray"

    app:layout_constraintTop_toBottomOf="@+id/text"

guuilp

<de.hdodenhof.circleimageview.CircleImageView
    android:id="@+id/profile_image"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:layout_marginTop="8dp"

    android:src="@drawable/profile_image"

    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"/>

guuilp

<android.support.constraint.Group
    android:id="@+id/group_retweet"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:constraint_referenced_ids="retweet_top, retweet_user"/>