<?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">

    <TextView
       android:id="@+id/YaziGoster1"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="Merhaba Türk Dünyası!"
       app:layout_constraintBottom_toBottomOf="parent"
       app:layout_constraintEnd_toEndOf="parent"
       app:layout_constraintStart_toStartOf="parent"
       app:layout_constraintTop_toTopOf="parent"
       android:textSize="14pt"/>

</androidx.constraintlayout.widget.ConstraintLayout>

package com.example.myapplication4;

import androidx.appcompat.app.AppCompatActivity;

import android.graphics.Color;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.widget.TextView;

import java.util.Random;

public class MainActivity extends AppCompatActivity {

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


        TextView YaziGosterNesnesi = (TextView) findViewById(R.id.YaziGoster1);


            new CountDownTimer(10000, 1000) {

                public void onTick(long millisUntilFinished) {
                    Random Renk = new Random();
                    YaziGosterNesnesi.setTextColor(Color.rgb(Renk.nextInt(255),Renk.nextInt(255),Renk.nextInt(255)));
                    YaziGosterNesnesi.setText("Bilişim Teknolojileri :" + millisUntilFinished / 1000);

                }

                public void onFinish() {
                    YaziGosterNesnesi.setTextColor(Color.rgb(255,0,0));
                    YaziGosterNesnesi.setText("Hoşgeldiniz.");
                }
            }.start();

    }
}