Basic Droidgram by Coach Paco. This is a basic implementation, not using classes.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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="match_parent"
    tools:context=".MainActivity">



    <ScrollView
        android:id="@+id/scrollView2"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginBottom="44dp"
        android:background="@color/colorAccent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <TextView
                android:id="@+id/textView4"
                android:layout_width="376dp"
                android:layout_height="52dp"
                android:layout_marginStart="10dp"
                android:layout_marginTop="20dp"
                android:layout_marginEnd="10dp"
                android:text="User name"
                app:layout_constraintBottom_toTopOf="@+id/scrollView2"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintHorizontal_bias="0.496"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent" />

            <ImageView
                android:id="@+id/imageView"
                android:layout_width="match_parent"
                android:layout_height="349dp"
                app:srcCompat="@drawable/android_paco" />

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:orientation="horizontal">

                <TextView
                    android:id="@+id/likesTxtView"
                    android:layout_width="301dp"
                    android:layout_height="48dp"
                    android:layout_marginLeft="10dp"
                    android:text="Likes: " />

                <Button
                    android:id="@+id/likeBtn"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginRight="10dp"
                    android:onClick="addLike"
                    android:text="Like" />
            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:orientation="horizontal">

                <EditText
                    android:id="@+id/editText"
                    android:layout_width="291dp"
                    android:layout_height="match_parent"
                    android:layout_marginLeft="10dp"
                    android:ems="10"
                    android:inputType="textPersonName"
                    android:text="Name" />

                <ImageButton
                    android:id="@+id/setMessageBtn"
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:layout_marginRight="10dp"
                    android:onClick="setMessages"
                    app:srcCompat="@android:drawable/ic_menu_send" />
            </LinearLayout>

            <TextView
                android:id="@+id/messageTxtView"
                android:layout_width="match_parent"
                android:layout_marginTop="20dp"
                android:layout_height="wrap_content"
                android:layout_marginLeft="10dp"
                android:text="TextView" />

        </LinearLayout>


    </ScrollView>


</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java

package com.example.scrollviewexample;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.TextView;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    private Button likeBtn;
    private ImageButton sendMsgBtn;
    private EditText inputTxt;
    private TextView outputTxt;
    private TextView likesTxt;

    int likes = 0;

    private ArrayList<String> messages = new ArrayList<>();


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

        likeBtn = findViewById(R.id.likeBtn);
        sendMsgBtn = findViewById(R.id.setMessageBtn);
        inputTxt = findViewById(R.id.editText);
        outputTxt =findViewById(R.id.messageTxtView);
        likesTxt = findViewById(R.id.likesTxtView);

        messages.clear();
        outputTxt.setTextSize(30);



    }

    public void setMessages(View v){


        if(inputTxt.getText().length() > 1 ) {

            String newMessage = inputTxt.getText().toString() + "\n";

            messages.add(newMessage);

            displayMessages();

            Log.d("msg:", "" + messages);

            inputTxt.setText("");

        }



    }

    public void addLike(View v){

        likes++;

        likesTxt.setText("Likes: " + likes);

    }

    public void displayMessages(){

        outputTxt.setText("");

        if (messages.size() > 0) {

            for (int i = 0; i < messages.size(); i++) {

                outputTxt.append(messages.get(i));
            }

        }
    }
}