Practical NO.

28 : Create login application where you will have to

validate username and password till the username and password is not
validated, login button should remain disabled.

• activity_main.xml

<androidx.constraintlayout.widget.ConstraintLa />
yout
<!-- Password Input -->
xmlns:android="http://schemas.android.com/ <EditText
apk/res/android" android:id="@+id/passwordEditText"
xmlns:app="http://schemas.android.com/apk/ android:layout_width="0dp"
res-auto" android:layout_height="wrap_content"
android:layout_width="match_parent" android:layout_marginStart="16dp"
android:layout_height="match_parent"> android:layout_marginTop="16dp"
android:layout_marginEnd="16dp"
<!-- Background Image (with Crop) -->
<ImageView android:background="@android:color/white
android:id="@+id/backgroundImage" "
android:layout_width="0dp" android:hint="Password"
android:layout_height="0dp" android:imeOptions="actionDone"
android:scaleType="centerCrop" android:inputType="textPassword"
android:src="@drawable/bgimg" android:singleLine="true"

app:layout_constraintTop_toTopOf="parent" app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintBottom_toBottomOf="
parent" app:layout_constraintStart_toStartOf="paren
app:layout_constraintStart_toStartOf="paren t"
t"
app:layout_constraintEnd_toEndOf="parent" app:layout_constraintTop_toBottomOf="@i
/> d/usernameEditText"/>
<!-- Username Input -->
<EditText <!-- Login Button -->
android:id="@+id/usernameEditText" <Button
android:layout_width="0dp" android:id="@+id/loginButton"
android:layout_height="wrap_content" android:layout_width="wrap_content"
android:layout_marginStart="16dp" android:layout_height="wrap_content"
android:layout_marginTop="312dp" android:layout_marginTop="24dp"
android:layout_marginEnd="16dp"
android:background="@android:color/black"
android:background="@android:color/white android:enabled="false"
" android:text="Login"
android:hint="Username"
android:imeOptions="actionNext" android:textColor="@android:color/white"
android:inputType="text" app:layout_constraintEnd_toEndOf="parent"
android:singleLine="true" app:layout_constraintStart_toStartOf="paren
t"
app:layout_constraintEnd_toEndOf="parent" app:layout_constraintTop_toBottomOf="@i
app:layout_constraintStart_toStartOf="paren d/passwordEditText"/>
t"
</androidx.constraintlayout.widget.Constrain
app:layout_constraintTop_toTopOf="parent" tLayout>
• MainActivity.java

package com.example.twentyeight; EditText fields

private final TextWatcher textWatcher =
import android.os.Bundle; new TextWatcher() {
import android.text.Editable; @Override
import android.text.TextWatcher; public void
import android.widget.Button; beforeTextChanged(CharSequence s, int start,
import android.widget.EditText; int count, int after) {}

import @Override
androidx.appcompat.app.AppCompatActivity; public void
onTextChanged(CharSequence s, int start, int
public class MainActivity extends before, int count) {}
AppCompatActivity {
@Override
private EditText usernameEditText, public void afterTextChanged(Editable
passwordEditText; s) {
private Button loginButton; validateInputs();
}
@Override };
protected void onCreate(Bundle
savedInstanceState) { // Method to validate username and
super.onCreate(savedInstanceState); password
setContentView(R.layout.activity_main); private void validateInputs() {
String username =
usernameEditText = usernameEditText.getText().toString().trim();
findViewById(R.id.usernameEditText); String password =
passwordEditText = passwordEditText.getText().toString().trim();
findViewById(R.id.passwordEditText);
loginButton = // Check if username and password meet
findViewById(R.id.loginButton); the required conditions
boolean isUsernameValid =
// Add text change listeners to both username.length() >= 3; // Username must be
EditText fields at least 3 characters
boolean isPasswordValid =
usernameEditText.addTextChangedListener(t password.length() >= 6; // Password must be
extWatcher); at least 6 characters

passwordEditText.addTextChangedListener(t // Enable button only when both fields

extWatcher); are valid

// Initially disable the login button loginButton.setEnabled(isUsernameValid &&

loginButton.setEnabled(false); isPasswordValid);
} }
}
// TextWatcher to monitor changes in
Output: