How to disable a button when Edittext Field empty in android studio

Hello friends today we will learn about how to disable a button when Edittext Field empty in android studio.

activity_main

<?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/textView5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:text="Admin name :"
        android:textSize="20sp"
        app:layout_constraintBottom_toBottomOf="@+id/userName"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="1.0" />

    <EditText
        android:id="@+id/userName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="32dp"
        android:ems="10"
        android:hint="Enter user name"
        android:inputType="textPersonName"
        app:layout_constraintBottom_toTopOf="@+id/password"
        app:layout_constraintStart_toEndOf="@+id/textView5"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.894" />

    <TextView
        android:id="@+id/textView4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:text="Password :"
        android:textSize="20sp"
        app:layout_constraintBottom_toBottomOf="@+id/password"
        app:layout_constraintStart_toStartOf="parent" />

    <EditText
        android:id="@+id/password"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="424dp"
        android:ems="10"
        android:hint="Password"
        android:inputType="numberPassword"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="@+id/userName" />

    <Button
        android:id="@+id/login"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Log in"
        android:enabled="false"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity

package com.example.disablebutton;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.os.Handler;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    private EditText userName, passwordName;
    private Button btn;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn = findViewById(R.id.login);
        userName = findViewById(R.id.userName);
        passwordName = findViewById(R.id.password);

        userName.addTextChangedListener(textWatcher);
        passwordName.addTextChangedListener(textWatcher);
    }

     private TextWatcher textWatcher=new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {



        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            String user = userName.getText().toString().trim();
            String password = passwordName.getText().toString().trim();
            btn.setEnabled(!user.isEmpty()&& !password.isEmpty());

        }

        @Override
        public void afterTextChanged(Editable s) {


        }
    };
}