login_screen.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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">


    <ImageView
        android:id="@+id/imageView"
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:scaleType="centerCrop"
        app:srcCompat="@drawable/icon_app_2"
        android:layout_marginLeft="36dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:layout_marginTop="80dp" />

    <TextView
        android:textStyle="bold"
        android:textColor="#4a4a4a"
        android:textSize="32sp"
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Welcome Back,"
        android:layout_marginLeft="36dp"
        app:layout_constraintLeft_toLeftOf="parent"
        android:layout_marginTop="36dp"
        app:layout_constraintTop_toBottomOf="@+id/imageView" />

    <TextView
        android:textColor="#bdbdbd"
        android:textSize="16sp"
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Please to Log In to acces."
        android:layout_marginLeft="36dp"
        app:layout_constraintLeft_toLeftOf="parent"
        android:layout_marginTop="12dp"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

    <EditText
        android:background="@drawable/username"
        android:id="@+id/editText"
        android:layout_width="0dp"
        android:layout_height="45dp"
        android:paddingLeft="60dp"
        android:inputType="textPersonName"
        android:text="Username"
        android:layout_marginLeft="36dp"
        app:layout_constraintLeft_toLeftOf="parent"
        android:layout_marginRight="36dp"
        app:layout_constraintRight_toRightOf="parent"
        android:layout_marginTop="36dp"
        app:layout_constraintTop_toBottomOf="@+id/textView2" />

    <EditText
        android:background="@drawable/password"
        android:id="@+id/editText2"
        android:layout_width="0dp"
        android:layout_height="45dp"
        android:paddingLeft="60dp"
        android:inputType="textPassword"
        android:text="Username"
        android:layout_marginLeft="36dp"
        app:layout_constraintLeft_toLeftOf="parent"
        android:layout_marginRight="36dp"
        app:layout_constraintRight_toRightOf="parent"
        android:layout_marginTop="16dp"
        app:layout_constraintTop_toBottomOf="@+id/editText" />

    <Button
        android:id="@+id/button"
        android:layout_width="0dp"
        android:layout_height="55dp"
        android:background="@drawable/btn_sign_in"
        android:layout_marginLeft="26dp"
        app:layout_constraintLeft_toLeftOf="parent"
        android:layout_marginRight="26dp"
        app:layout_constraintRight_toRightOf="parent"
        android:layout_marginTop="36dp"
        app:layout_constraintTop_toBottomOf="@+id/editText2" />
</android.support.constraint.ConstraintLayout>