android.support.design.widget.TextInputLayout could not be instantiated

replace

android.support.design.widget.TextInputLayout

with

com.google.android.material.textfield.TextInputLayout

If you uses AndroidStudio, you should not include android-support-design.jar.
Instead, write like below in your build.gradle:

dependencies {
    ...
    compile 'com.android.support:design:24.0.0'
    ...
}

Edit: If this doesn’t work you are probably using a different version. In Windows, go to:

[android-sdk]extrasandroidm2repositorycomandroidsupportdesign

On Mac:

sdk/extras/android/m2repository/com/android/support/design

This directory holds a number of version folders. Use the latest version on your build.gradle.

add in the build.gradle following this line:

implementation 'com.android.support:design:28.0.0'

and use in the xml file:

 <com.google.android.material.textfield.TextInputLayout
                    android:id="@+id/inputLayoutMobile"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_marginLeft="@dimen/dimen_20dp"
                    android:layout_marginRight="@dimen/dimen_20dp"
                    android:hint="@string/phone_number"
                    android:visibility="gone"
                    android.support.design:layout_constraintTop_toBottomOf="@+id/inputLayoutAppServerUrl">

                    <com.google.android.material.textfield.TextInputEditText
                        android:id="@+id/edtTxtMobile"
                        style="@style/Style_TextView"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:drawableLeft="@drawable/ic_smartphone"
                        android:drawablePadding="@dimen/dimen_10dp"
                        android:inputType="number"
                        android:singleLine="true"
                        android:scrollbars="vertical"
                        android:text="@={SettingViewModel.mMobileNo}"
                        android:textSize="@dimen/font_13sp" />
                </com.google.android.material.textfield.TextInputLayout>