activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<!--Code From Learnoset - Learn Coding Online.-->
<!--Download Learnoset App from PlayStore to learn coding,projects-->

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">
    
    <EditText
        android:hint="Enter Text"
        android:id="@+id/animateTxt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp" />

    <androidx.appcompat.widget.AppCompatButton
        android:id="@+id/animateBtn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:text="Animate Text" />
</LinearLayout>

MainActivity.java

/* Code From Learnoset - Learn Coding Online.*/
/* Download Learnoset App from PlayStore to learn coding,
 * projects
 */

import android.os.Bundle;
import android.os.CountDownTimer;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    int count = 0;
    private boolean isAnimating = false;

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

        final EditText animateEditText = findViewById(R.id.animateTxt);
        final Button animateBtn = findViewById(R.id.animateBtn);


        animateBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if (!isAnimating) {
                    isAnimating = true;

                    final String animateTxt = animateEditText.getText().toString();
                    animateEditText.setText("");
                    count = 0;

                    new CountDownTimer(animateTxt.length() * 100, 100) {
                        @Override
                        public void onTick(long millisUntilFinished) {
                            animateEditText.setText(animateEditText.getText().toString() + animateTxt.charAt(count));
                            count++;
                        }

                        @Override
                        public void onFinish() {
                            isAnimating = false;
                        }
                    }.start();
                }
            }
        });

    }
}