<?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/tv0"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="LOGIN FORM "
android:textColor="@color/black"
android:textSize="40dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.497"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.041" />

<TextView
android:id="@+id/tv1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
android:layout_marginRight="40dp"
android:text="USERNAME"
android:textColor="@color/black"
android:textSize="30dp"
app:layout_constraintHorizontal_bias="0.075"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@id/tv0" />

<TextView

android:id="@+id/tv2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="50dp"
android:layout_marginRight="40dp"
android:text="PASSWORD"
android:textColor="@color/black"
android:textSize="30dp"
 app:layout_constraintHorizontal_bias="0.075"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@id/tv1" />

<EditText
android:id="@+id/edu"
android:layout_width="200dp"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:layout_marginTop="24dp"
android:layout_marginEnd="16dp"
android:hint="USERNAME"
android:textSize="20dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintLeft_toRightOf="@id/tv1"
app:layout_constraintTop_toBottomOf="@id/tv0" />

<EditText
android:id="@+id/edp"
android:layout_width="200dp"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:layout_marginTop="48dp"
android:layout_marginEnd="16dp"
android:textSize="20dp"
android:hint="PASSWORD"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintLeft_toRightOf="@id/tv2"
app:layout_constraintTop_toBottomOf="@id/edu" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/bus"
app:layout_constraintTop_toBottomOf="@id/edp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:text="LOGIN"
android:enabled="false"

android:layout_marginTop="50dp"/>
</androidx.constraintlayout.widget.ConstraintLayout>

package com.example.lpogon;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {

EditText e1, e2;
Button b;

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

e1 = findViewById(R.id.edu);
e2 = findViewById(R.id.edp);
b = findViewById(R.id.bus);

e1.addTextChangedListener(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) {
checkCredentials();
}

@Override
public void afterTextChanged(Editable s) {
}
});

e2.addTextChangedListener(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) {
checkCredentials();
}

@Override
public void afterTextChanged(Editable s) {
}
});
 }

private void checkCredentials() {

if (e1.getText().toString().equals("admin") && e2.getText().toString().equals("admin123")) {
b.setEnabled(true);
} else {
b.setEnabled(false);
}
}
}