Android ScrollView Error - IllegalStateException: ScrollView can host only one direct child

Question

I have been getting this "ScrollView can host only one direct child" even though I am only using one main layout in the layout XML code. Basically what I'm trying to do is call/start the RegisterFragment from the LoginFragment. I am trying to do that using the following code:

     @Override
public void onClick(View view) {
    switch (view.getId()) {
        case R.id.vvLoginBanner: toggleVolume(); break;
        case R.id.btnLogin:      login(); break;
        case R.id.tvSignup:      FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.replace(R.id.loginFragmentLayout, new RegisterFragment());
            fragmentTransaction.addToBackStack(null);
            fragmentTransaction.commit();
            break;
    }
}

Here is the code for both of these XML file that could be possibly causing the error:

LoginFragment.xml

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/loginFragmentContainer"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:isScrollContainer="true"
tools:context="com.bvmobileapps.bvmobileapps.LoginFragment">

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <FrameLayout
        android:id="@+id/flBannerProgressBarWrapper"
        android:layout_alignParentTop="true"
        android:layout_width="match_parent"
        android:background="@color/black"
        android:layout_height="wrap_content">

        <ProgressBar
            android:id="@+id/pbBanner"
            android:layout_gravity="center"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:indeterminate="true"/>

    </FrameLayout>

<androidx.core.widget.NestedScrollView
    android:id="@+id/nsvScrollView"
    android:layout_below="@id/rlVideoWrapper"
    android:isScrollContainer="false"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <LinearLayout
        android:id="@+id/loginFragmentLayout"
        android:isScrollContainer="true"
        android:orientation="vertical"
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <FrameLayout
            android:id="@+id/fragmentFrameLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
        <LinearLayout
            android:id="@+id/llBannerWrapper"
            android:weightSum="100"
            android:orientation="horizontal"
            android:layout_marginTop="@dimen/inter_item_margin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <View
                android:layout_weight="10"
                android:layout_width="0dp"
                android:layout_height="1px"/>

            <ImageView
                android:id="@+id/ivBanner"
                android:src="@drawable/bv_banner"
                android:layout_weight="80"
                android:layout_width="0dp"
                android:layout_height="wrap_content" />

        </LinearLayout>

        <com.google.android.material.textfield.TextInputLayout
            android:layout_marginStart="@dimen/inter_item_margin"
            android:layout_marginEnd="@dimen/inter_item_margin"
            android:layout_marginBottom="@dimen/intra_item_margin"
            android:layout_marginTop="@dimen/inter_item_margin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <com.google.android.material.textfield.TextInputEditText
                android:id="@+id/tvUsername"
                android:hint="@string/username_hint"
                android:singleLine="true"
                android:maxLength="20"
                android:imeOptions="actionNext"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

        </com.google.android.material.textfield.TextInputLayout>

        <com.google.android.material.textfield.TextInputLayout
            android:layout_marginStart="@dimen/inter_item_margin"
            android:layout_marginEnd="@dimen/inter_item_margin"
            android:layout_marginTop="@dimen/intra_item_margin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <com.google.android.material.textfield.TextInputEditText
                android:id="@+id/tvPassword"
                android:hint="@string/password_hint"
                android:fontFamily="@font/segoe_ui_light"
                android:maxLength="20"
                android:singleLine="true"
                android:imeOptions="actionDone"
                android:inputType="textPassword"
                android:gravity="start"
                android:ellipsize="start"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

        </com.google.android.material.textfield.TextInputLayout>

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal">


            <androidx.appcompat.widget.AppCompatButton
                android:id="@+id/btnLogin"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:textColor="@color/white"
                android:layout_margin="@dimen/inter_item_margin"
                android:fontFamily="@font/segoe_ui_semi_bold"
                android:text="@string/login_btn"
                app:backgroundTint="@color/bv_blue" />

            <ProgressBar
                android:id="@+id/pbLogin"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:visibility="gone" />

        </RelativeLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="-14dp"
            android:layout_marginBottom="@dimen/inter_item_margin"
            android:gravity="center"
            android:orientation="horizontal">

            <TextView
                android:id="@+id/tvSignup"
                android:text="@string/signup"
                android:textSize="@dimen/smallest_text"
                android:textColor="@color/bv_blue"
                android:textAlignment="center"
                android:layout_marginRight="20dp"
                android:layout_width="150dp"
                android:layout_height="wrap_content" />

            <TextView
                android:id="@+id/tvForgotPassword"
                android:text="@string/forgot_password"
                android:textSize="@dimen/smallest_text"
                android:textColor="@color/bv_blue"
                android:textAlignment="center"
                android:layout_marginLeft="0dp"
                android:layout_width="150dp"
                android:layout_height="wrap_content" />
        </LinearLayout>
    </LinearLayout>
</androidx.core.widget.NestedScrollView>
</RelativeLayout>

RegisterFragment.xml

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/registerFragmentContainer"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:isScrollContainer="true"
tools:context="com.bvmobileapps.bvmobileapps.RegisterFragment">

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <FrameLayout
        android:id="@+id/flBannerProgressBarWrapper"
        android:layout_alignParentTop="true"
        android:layout_width="match_parent"
        android:background="@color/black"
        android:layout_height="wrap_content">

        <ProgressBar
            android:id="@+id/pbBanner"
            android:layout_gravity="center"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:indeterminate="true"/>

    </FrameLayout>

<androidx.core.widget.NestedScrollView
    android:id="@+id/nsvScrollView"
    android:layout_below="@id/rlVideoWrapper"
    android:isScrollContainer="false"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <LinearLayout
        android:isScrollContainer="true"
        android:orientation="vertical"
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

    <RelativeLayout
        android:id="@+id/registerFragmentLayout"
        android:layout_marginStart="@dimen/inter_item_margin"
        android:layout_marginEnd="@dimen/inter_item_margin"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="0dp"
        android:layout_marginBottom="0dp"
        android:gravity="center_horizontal"
        android:weightSum="10"
        android:orientation="horizontal">
        <ImageView
            android:id="@+id/ivValidUsername"
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:layout_gravity="center_horizontal"
            android:layout_marginTop="21dp"
            android:layout_marginBottom="@dimen/intra_item_margin"
            android:scaleType="fitXY"
            android:src="@drawable/red_error" />
        <com.google.android.material.textfield.TextInputLayout
            android:layout_marginStart="@dimen/inter_item_margin"
            android:layout_marginEnd="@dimen/inter_item_margin"
            android:layout_marginBottom="@dimen/intra_item_margin"
            android:layout_marginTop="@dimen/inter_item_margin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <com.google.android.material.textfield.TextInputEditText
                android:id="@+id/tvUsername"
                android:hint="@string/username_hint"
                android:singleLine="true"
                android:maxLength="20"
                android:layout_marginLeft="@dimen/inter_item_margin_left"
                android:imeOptions="actionNext"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />
        </com.google.android.material.textfield.TextInputLayout>
    </RelativeLayout>

        <include layout="@layout/horizontal_divider"
            android:id="@+id/source_divider"
            android:layout_marginTop="@dimen/intra_item_margin"
            android:layout_width="match_parent"
            android:layout_height="1dp"
            app:layout_constraintTop_toBottomOf="@id/photo_source_edit_text_wrapper"/>
    <RelativeLayout
        android:layout_marginStart="@dimen/inter_item_margin"
        android:layout_marginEnd="@dimen/inter_item_margin"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="0dp"
        android:layout_marginBottom="0dp"
        android:gravity="center_horizontal"
        android:weightSum="10"
        android:orientation="horizontal">
        <ImageView
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:id="@+id/ivValidEmail"
            android:layout_gravity="center_horizontal"
            android:src="@drawable/red_error"
            android:scaleType="fitXY"/>
        <com.google.android.material.textfield.TextInputLayout
            android:layout_marginStart="@dimen/inter_item_margin"
            android:layout_marginEnd="@dimen/inter_item_margin"
            android:layout_marginTop="@dimen/intra_item_margin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
            <com.google.android.material.textfield.TextInputEditText
                android:id="@+id/tvEmail"
                android:hint="@string/email_hint"
                android:fontFamily="@font/segoe_ui_light"
                android:maxLength="20"
                android:singleLine="true"
                android:imeOptions="actionDone"
                android:inputType="text"
                android:gravity="start"
                android:ellipsize="start"
                android:layout_marginLeft="@dimen/inter_item_margin_left"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

        </com.google.android.material.textfield.TextInputLayout>
    </RelativeLayout>

        <include layout="@layout/horizontal_divider"
            android:id="@+id/source_divider"
            android:layout_marginTop="@dimen/intra_item_margin"
            android:layout_width="match_parent"
            android:layout_height="1dp"
            app:layout_constraintTop_toBottomOf="@id/photo_source_edit_text_wrapper"/>

    <RelativeLayout
        android:layout_marginStart="@dimen/inter_item_margin"
        android:layout_marginEnd="@dimen/inter_item_margin"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="0dp"
        android:layout_marginBottom="0dp"
        android:gravity="center_horizontal"
        android:weightSum="10"
        android:orientation="horizontal">
        <ImageView
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:id="@+id/ivValidPassword"
            android:layout_gravity="center_horizontal"
            android:src="@drawable/red_error"
            android:scaleType="fitXY"/>
        <com.google.android.material.textfield.TextInputLayout
            android:layout_marginStart="@dimen/inter_item_margin"
            android:layout_marginEnd="@dimen/inter_item_margin"
            android:layout_marginTop="@dimen/intra_item_margin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <com.google.android.material.textfield.TextInputEditText
                android:id="@+id/tvPassword"
                android:hint="@string/password_hint"
                android:fontFamily="@font/segoe_ui_light"
                android:maxLength="20"
                android:singleLine="true"
                android:imeOptions="actionDone"
                android:inputType="textPassword"
                android:gravity="start"
                android:ellipsize="start"
                android:layout_marginLeft="@dimen/inter_item_margin_left"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

        </com.google.android.material.textfield.TextInputLayout>
    </RelativeLayout>
        <include layout="@layout/horizontal_divider"
            android:id="@+id/source_divider"
            android:layout_marginTop="@dimen/intra_item_margin"
            android:layout_width="match_parent"
            android:layout_height="1dp"
            app:layout_constraintTop_toBottomOf="@id/photo_source_edit_text_wrapper"/>

        <LinearLayout
            android:layout_marginStart="@dimen/inter_item_margin"
            android:layout_marginEnd="@dimen/inter_item_margin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="0dp"
            android:layout_marginBottom="0dp"
            android:gravity="center_horizontal"
            android:weightSum="10"
            android:orientation="horizontal">

            <com.google.android.material.textfield.TextInputLayout
                android:layout_marginTop="@dimen/intra_item_margin"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_weight="5">

                <com.google.android.material.textfield.TextInputEditText
                    android:id="@+id/tvFirstName"
                    android:hint="@string/first_name_hint"
                    android:fontFamily="@font/segoe_ui_light"
                    android:maxLength="20"
                    android:singleLine="true"
                    android:imeOptions="actionDone"
                    android:inputType="text"
                    android:gravity="start"
                    android:ellipsize="start"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content" />

            </com.google.android.material.textfield.TextInputLayout>

            <com.google.android.material.textfield.TextInputLayout
                android:layout_marginTop="@dimen/intra_item_margin"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_weight="5">

                <com.google.android.material.textfield.TextInputEditText
                    android:id="@+id/tvLastName"
                    android:hint="@string/last_name_hint"
                    android:fontFamily="@font/segoe_ui_light"
                    android:maxLength="20"
                    android:singleLine="true"
                    android:imeOptions="actionDone"
                    android:inputType="text"
                    android:gravity="start"
                    android:ellipsize="start"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content" />

            </com.google.android.material.textfield.TextInputLayout>

        </LinearLayout>

        <com.google.android.material.textfield.TextInputLayout
            android:layout_marginStart="@dimen/inter_item_margin"
            android:layout_marginEnd="@dimen/inter_item_margin"
            android:layout_marginTop="@dimen/intra_item_margin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
            <Spinner
                android:id="@+id/spGender"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="20dp"/>

        </com.google.android.material.textfield.TextInputLayout>
        <com.google.android.material.textfield.TextInputLayout
            android:layout_marginStart="@dimen/inter_item_margin"
            android:layout_marginEnd="@dimen/inter_item_margin"
            android:layout_marginTop="@dimen/intra_item_margin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <com.google.android.material.textfield.TextInputEditText
                android:id="@+id/tvZipCode"
                android:hint="@string/confirm_password_hint"
                android:fontFamily="@font/segoe_ui_light"
                android:maxLength="20"
                android:singleLine="true"
                android:imeOptions="actionDone"
                android:inputType="textPassword"
                android:gravity="start"
                android:ellipsize="start"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

        </com.google.android.material.textfield.TextInputLayout>
        <LinearLayout
            android:layout_marginStart="@dimen/inter_item_margin"
            android:layout_marginEnd="@dimen/inter_item_margin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="0dp"
            android:layout_marginBottom="0dp"
            android:gravity="center_horizontal"
            android:weightSum="25"
            android:orientation="horizontal">

            <TextView
                android:id="@+id/tvBirthDate"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginStart="@dimen/inter_item_margin"
                android:layout_marginEnd="@dimen/inter_item_margin"
                android:layout_marginTop="@dimen/intra_item_margin"
                android:text="DateTime"/>

        </LinearLayout>

        <include layout="@layout/horizontal_divider"
            android:id="@+id/source_divider"
            android:layout_marginTop="@dimen/intra_item_margin"
            android:layout_width="match_parent"
            android:layout_height="1dp"
            app:layout_constraintTop_toBottomOf="@id/photo_source_edit_text_wrapper"/>

        <com.google.android.material.textfield.TextInputLayout
            android:layout_marginStart="@dimen/inter_item_margin"
            android:layout_marginEnd="@dimen/inter_item_margin"
            android:layout_marginTop="@dimen/intra_item_margin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <com.google.android.material.textfield.TextInputEditText
                android:id="@+id/tvSecurityQuestion"
                android:hint="@string/secret_question_hint"
                android:fontFamily="@font/segoe_ui_light"
                android:maxLength="20"
                android:singleLine="true"
                android:imeOptions="actionDone"
                android:inputType="textPassword"
                android:gravity="start"
                android:ellipsize="start"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

        </com.google.android.material.textfield.TextInputLayout>
        <com.google.android.material.textfield.TextInputLayout
            android:layout_marginStart="@dimen/inter_item_margin"
            android:layout_marginEnd="@dimen/inter_item_margin"
            android:layout_marginTop="@dimen/intra_item_margin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <com.google.android.material.textfield.TextInputEditText
                android:id="@+id/tvSecurityQuestionAnswer"
                android:hint="@string/secret_question_answer_hint"
                android:fontFamily="@font/segoe_ui_light"
                android:maxLength="20"
                android:singleLine="true"
                android:imeOptions="actionDone"
                android:inputType="textPassword"
                android:gravity="start"
                android:ellipsize="start"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

        </com.google.android.material.textfield.TextInputLayout>
        <CheckBox
            android:id="@+id/agree"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="@dimen/appbar_padding_top"
            android:checked="true"
            android:text="@string/checkbox_label_termscond" />
        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal">

            <androidx.appcompat.widget.AppCompatButton
                android:id="@+id/btnRegister"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:textColor="@color/white"
                android:layout_margin="@dimen/inter_item_margin"
                android:fontFamily="@font/segoe_ui_semi_bold"
                android:text="@string/submit_btn"
                app:backgroundTint="@color/bv_blue" />

            <ProgressBar
                android:id="@+id/pbRegister"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:visibility="gone" />
        </RelativeLayout>
    </LinearLayout>
</androidx.core.widget.NestedScrollView>
</RelativeLayout>

Here is following error message produced in the logcat:

java.lang.IllegalStateException: ScrollView can host only one direct child
    at android.widget.ScrollView.addView(ScrollView.java:273)
    at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManager.java:1466)
    at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1784)
    at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManager.java:1852)
    at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:802)
    at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManager.java:2625)
    at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2411)
    at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2366)
    at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2273)
    at androidx.fragment.app.FragmentManagerImpl$1.run(FragmentManager.java:733)
    at android.os.Handler.handleCallback(Handler.java:790)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:6651)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:810)

Now I made sure that in the layout I only include one main layout with other nested layouts included in that main layout. So, based on that I don't think I should be getting that error. Any help or advice to fix this problem would be greatly appreciated!

Answer 1

There must be only one child view in ScrollView. You are getting this error because you are not using the full closing tag.

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:tools="http://schemas.android.com/tools"
            xmlns:app="http://schemas.android.com/apk/res-auto"
            android:id="@+id/loginFragmentContainer"
            android:orientation="vertical"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:isScrollContainer="true"
            tools:context="com.bvmobileapps.bvmobileapps.LoginFragment">
        
    <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
    ....
    </RelativeLayout>
</ScrollView> 

Answer 2

You are missing a closing tag for your Scroll View in your xml files. Btw, Consider using nested scroll view instead of scroll view.(As mentioned in the documentation)

Also you should avoid using scroll view inside another scroll view.

Suggestion : Avoid nesting too much to enhance layout performance. Have a look : Performance and view hierarchies