“ScrollView 只能承载 1 个孩子”在 2 个片段中只有 1 个孩子？

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【中文标题】“ScrollView 只能承载 1 个孩子”在 2 个片段中只有 1 个孩子？【英文标题】："ScrollView can only host 1 child" in 2 fragments with only 1 child? 【发布时间】：2020-07-02 04:14:22 【问题描述】：

我有 2 个片段，每个片段都有一个 ScrollView，内部有 1 个 ConstraintLayout。 ContraintLayout 内部包含多个孩子，但 ScrollViews 只有 1 个孩子。当我转到片段 1 时，我没有收到任何错误。我去片段2，一切都很好。但是，当我返回片段 1 时，出现以下错误：

2020-03-20 22:56:20.491 7887-7887/? E/androidRuntime: FATAL EXCEPTION: main
    Process: com.starenkysoftware.vanshapp, PID: 7887
    java.lang.IllegalStateException: ScrollView can host only one direct child
        at android.widget.ScrollView.addView(ScrollView.java:266)
        at com.google.android.material.snackbar.BaseTransientBottomBar.showView(BaseTransientBottomBar.java:719)
        at com.google.android.material.snackbar.BaseTransientBottomBar$1.handleMessage(BaseTransientBottomBar.java:243)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6898)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:537)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

我不明白这是怎么可能的，因为我在切换时没有在布局中添加任何其他内容

编辑：添加代码

片段 1：

<?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_
    android:layout_>

    <ScrollView
        android:layout_
        android:layout_>

        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_
            android:layout_>

    <TextView
        android:id="@+id/recipient_header"
        android:layout_
        android:layout_
        android:text="Beneficiary"
        android:textStyle="bold"
        android:textSize="15sp"
        android:textColor="@color/colorPrimary"
        android:layout_marginTop="20dp"
        android:layout_marginLeft="18dp"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"/>

    <View
        android:id="@+id/recipient_splitter"
        android:layout_
        android:layout_
        android:layout_marginTop="3dp"
        android:layout_marginLeft="18dp"
        android:layout_marginRight="18dp"
        android:background="@color/colorPrimary"
        app:layout_constraintTop_toBottomOf="@id/recipient_header"/>

    <!-- Recipient Name Fields -->

    <com.google.android.material.textfield.TextInputLayout
    android:id="@+id/recipient_first_name"
    android:layout_
    android:layout_
    android:layout_marginTop="30dp"
    android:layout_marginLeft="20dp"
        app:layout_constraintHorizontal_chainStyle="spread"
    android:layout_marginRight="10dp"
    app:layout_constraintTop_toBottomOf="@id/recipient_splitter"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toLeftOf="@id/recipient_middle_name"
    android:hint="First Name">

    <com.google.android.material.textfield.TextInputEditText
        android:id="@+id/first_name_field"
        android:inputType="textPersonName"
        android:layout_
        android:layout_/>

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

            <com.google.android.material.textfield.TextInputLayout
                android:id="@+id/recipient_middle_name"
                android:layout_
                android:layout_
                android:layout_marginTop="30dp"
                app:layout_constraintHorizontal_chainStyle="spread"
                app:layout_constraintTop_toBottomOf="@id/recipient_splitter"
                app:layout_constraintLeft_toRightOf="@id/recipient_first_name"
                app:layout_constraintRight_toLeftOf="@id/recipient_last_name"
                android:hint="Middle Name">

                <com.google.android.material.textfield.TextInputEditText
                    android:id="@+id/middle_name_field"
                    android:inputType="textPersonName"
                    android:layout_
                    android:layout_/>

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

    <com.google.android.material.textfield.TextInputLayout
        android:id="@+id/recipient_last_name"
        android:layout_
        android:layout_
        android:layout_marginLeft="10dp"
        android:layout_marginRight="20dp"
        app:layout_constraintHorizontal_chainStyle="spread"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="@+id/recipient_first_name"
        app:layout_constraintBottom_toBottomOf="@+id/recipient_first_name"
        app:layout_constraintLeft_toRightOf="@id/recipient_middle_name"
        android:hint="Last Name">

        <com.google.android.material.textfield.TextInputEditText
            android:id="@+id/last_name_field"
            android:inputType="textPersonName"
            android:layout_
            android:layout_/>

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

    <!-- Recipient Location Field -->

    <com.google.android.material.textfield.TextInputLayout
        android:id="@+id/recipient_state"
        android:layout_
        android:layout_
        android:layout_marginTop="30dp"
        android:layout_marginLeft="20dp"
        app:layout_constraintHorizontal_chainStyle="spread"
        android:layout_marginRight="10dp"
        app:layout_constraintTop_toBottomOf="@id/recipient_first_name"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toLeftOf="@id/recipient_city"
        android:hint="Province">

        <com.google.android.material.textfield.TextInputEditText
            android:id="@+id/state_field"
            android:inputType="textPersonName"
            android:layout_
            android:layout_/>

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

    <com.google.android.material.textfield.TextInputLayout
        android:id="@+id/recipient_city"
        android:layout_
        android:layout_
        android:layout_marginLeft="10dp"
        android:layout_marginRight="20dp"
        app:layout_constraintHorizontal_chainStyle="spread"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="@+id/recipient_state"
        app:layout_constraintBottom_toBottomOf="@+id/recipient_state"
        app:layout_constraintLeft_toRightOf="@id/recipient_state"
        android:hint="City">

        <com.google.android.material.textfield.TextInputEditText
            android:id="@+id/city_field"
            android:inputType="textPersonName"
            android:layout_
            android:layout_/>

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

    <!-- Phone Number -->
    <com.google.android.material.textfield.TextInputLayout
        android:id="@+id/phone_number_layout"
        app:prefixText=""
        android:layout_
        android:layout_
        android:layout_marginTop="30dp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        app:layout_constraintTop_toBottomOf="@id/recipient_state"
        android:hint="Phone Number">

        <com.google.android.material.textfield.TextInputEditText
            android:id="@+id/phone_number_field"
            android:layout_
            android:layout_
            android:inputType="phone"/>

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

    <!-- Transger Info Section -->
    <TextView
        android:id="@+id/transfer_info_header"
        android:layout_
        android:layout_
        android:text="Transfer Info"
        android:textStyle="bold"
        android:textSize="15sp"
        android:textColor="@color/colorPrimary"
        android:layout_marginTop="25dp"
        android:layout_marginLeft="18dp"
        app:layout_constraintTop_toBottomOf="@id/phone_number_layout"
        app:layout_constraintLeft_toLeftOf="parent"/>

    <View
        android:id="@+id/transfer_info_splitter"
        android:layout_
        android:layout_
        android:layout_marginTop="3dp"
        android:layout_marginLeft="18dp"
        android:layout_marginRight="18dp"
        android:background="@color/colorPrimary"
        app:layout_constraintTop_toBottomOf="@id/transfer_info_header"/>

    <!-- SOF (Source of Fund -->
    <com.google.android.material.textfield.TextInputLayout
        android:id="@+id/sof_layout"
        app:prefixText=""
        android:layout_
        android:layout_
        android:layout_marginTop="30dp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        app:layout_constraintTop_toBottomOf="@id/transfer_info_splitter"
        android:hint="Source of Fund">

        <com.google.android.material.textfield.TextInputEditText
            android:id="@+id/sof_field"
            android:layout_
            android:layout_
            android:inputType="text"/>
    </com.google.android.material.textfield.TextInputLayout>

            <!-- Type of Transfer Dropdown -->
    <com.google.android.material.textfield.TextInputLayout
        style="@style/Widget.MaterialComponents.TextInputLayout.FilledBox.ExposedDropdownMenu"
        android:id="@+id/type_of_transfer_layout"
        android:layout_
        android:layout_
        android:layout_marginTop="30dp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:hint="Type"
        app:layout_constraintTop_toBottomOf="@id/sof_layout">

        <AutoCompleteTextView
            android:id="@+id/type_of_transfer_dropdown"
            android:editable="false"
            android:layout_
            android:layout_/>

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

            <androidx.constraintlayout.widget.ConstraintLayout
                android:id="@+id/btb_info"
                android:layout_
                android:layout_
                app:layout_constraintTop_toBottomOf="@id/type_of_transfer_layout">

            <!-- Bank Name -->
            <com.google.android.material.textfield.TextInputLayout
                android:id="@+id/bank_name_layout"
                app:prefixText=""
                android:layout_
                android:layout_
                android:layout_marginTop="30dp"
                android:layout_marginLeft="20dp"
                android:layout_marginRight="20dp"
                app:layout_constraintTop_toTopOf="parent"
                android:hint="Bank Name">

                <com.google.android.material.textfield.TextInputEditText
                    android:id="@+id/bank_name_field"
                    android:layout_
                    android:layout_
                    android:inputType="text"/>
            </com.google.android.material.textfield.TextInputLayout>

            <!-- Phone Number -->
            <com.google.android.material.textfield.TextInputLayout
                android:id="@+id/bank_account_number_layout"
                app:prefixText=""
                android:layout_
                android:layout_
                android:layout_marginTop="30dp"
                android:layout_marginLeft="20dp"
                android:layout_marginRight="20dp"
                app:layout_constraintTop_toBottomOf="@id/bank_name_layout"
                android:hint="Bank Account Number">

                <com.google.android.material.textfield.TextInputEditText
                    android:id="@+id/bank_account_number_field"
                    android:layout_
                    android:layout_
                    android:inputType="number"/>
            </com.google.android.material.textfield.TextInputLayout>
            </androidx.constraintlayout.widget.ConstraintLayout>

            <!-- Currency Selector -->
            <com.google.android.material.textfield.TextInputLayout
                style="@style/Widget.MaterialComponents.TextInputLayout.FilledBox.ExposedDropdownMenu"
                android:id="@+id/currency_selector_layout"
                android:layout_
                android:layout_
                android:layout_marginLeft="20dp"
                android:layout_marginRight="20dp"
                app:layout_constraintBottom_toBottomOf="@id/amount_layout"
                app:layout_constraintTop_toTopOf="@id/amount_layout"
                app:layout_constraintLeft_toLeftOf="parent">

                <AutoCompleteTextView
                    android:id="@+id/currency_dropdown"
                    android:editable="false"
                    android:layout_
                    android:layout_/>

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

    <!-- Amount Field -->


    <com.google.android.material.textfield.TextInputLayout
        android:id="@+id/amount_layout"
        app:prefixText=""
        app:suffixText="CAD"
        android:layout_
        android:layout_
        android:layout_marginTop="30dp"
        android:layout_marginLeft="35dp"
        android:layout_marginRight="20dp"
        app:layout_constraintTop_toBottomOf="@id/btb_info"
        app:layout_constraintLeft_toRightOf="@id/currency_selector_layout"
        android:hint="Amount">

        <com.google.android.material.textfield.TextInputEditText
            android:id="@+id/amount_field"
            android:layout_
            android:layout_
            android:inputType="numberDecimal" />

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

            <TextView
                android:id="@+id/currency_rate_small"
                android:layout_
                android:layout_
                android:layout_marginTop="2dp"
                android:text=""
                android:textSize="13sp"
                app:layout_constraintBottom_toTopOf="@+id/photo_checkbox"
                app:layout_constraintLeft_toLeftOf="@+id/amount_layout"
                app:layout_constraintTop_toBottomOf="@id/amount_layout" />

    <com.google.android.material.button.MaterialButton
        android:id="@+id/submit_button"
        style="@style/Widget.MaterialComponents.Button"
        android:layout_
        android:layout_
        android:layout_marginTop="20dp"
        android:layout_marginRight="20dp"
        android:text="Send"
        app:layout_constraintTop_toBottomOf="@+id/amount_layout"
        app:layout_constraintRight_toRightOf="parent"/>

            <com.google.android.material.button.MaterialButton
                android:id="@+id/photo_button"
                style="@style/Widget.MaterialComponents.Button"
                android:layout_
                android:layout_
                android:layout_marginTop="20dp"
                android:layout_marginLeft="20dp"
                android:text="Photo Verification"
                app:layout_constraintTop_toBottomOf="@+id/amount_layout"
                app:layout_constraintLeft_toLeftOf="parent"/>

            <CheckBox
                android:id="@+id/photo_checkbox"
                android:layout_
                android:layout_
                android:layout_marginLeft="5dp"
                android:clickable="false"
                app:layout_constraintBottom_toBottomOf="@id/photo_button"
                app:layout_constraintLeft_toRightOf="@id/photo_button"
                app:layout_constraintTop_toTopOf="@+id/photo_button"/>

            <View
                android:layout_
                android:layout_
                app:layout_constraintTop_toBottomOf="@id/submit_button"/>

        </androidx.constraintlayout.widget.ConstraintLayout>
    </ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>

片段 2：

<?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"
    android:layout_
    android:layout_>

    <ScrollView
        android:layout_
        android:layout_>

        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_
            android:layout_>
    <TextView
        android:id="@+id/previous_transfer_title"
        android:layout_
        android:layout_
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:text="Previous 5 Transfers"
        android:gravity="center"
        android:textSize="20sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <com.google.android.material.card.MaterialCardView
        android:id="@+id/materialCardView1"
        style="@style/Widget.MaterialComponents.CardView"
        android:layout_
        android:layout_
        android:layout_marginLeft="@dimen/mtrl_card_spacing"
        android:layout_marginRight="@dimen/mtrl_card_spacing"
        android:layout_marginTop="15dp"
        android:minHeight="100dp"
        app:cardBackgroundColor="#ffffff"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/previous_transfer_title">

        <TextView
            android:id="@+id/transfer_card_1_text"
            android:layout_
            android:layout_
            android:layout_marginLeft="10dp"
            android:layout_marginTop="3dp"
            android:text="Exchange Rate"
            android:textColor="#878787"
            android:textSize="20dp" />

        <View
            android:layout_
            android:layout_
            android:layout_gravity="bottom"
            android:background="@color/colorPrimary" />

    </com.google.android.material.card.MaterialCardView>

    <com.google.android.material.card.MaterialCardView
        android:id="@+id/materialCardView2"
        style="@style/Widget.MaterialComponents.CardView"
        android:layout_
        android:layout_
        android:layout_marginLeft="@dimen/mtrl_card_spacing"
        android:layout_marginRight="@dimen/mtrl_card_spacing"
        android:layout_marginTop="20dp"
        android:minHeight="100dp"
        app:cardBackgroundColor="#ffffff"
        app:layout_constraintTop_toBottomOf="@+id/materialCardView1">

        <TextView
            android:id="@+id/transfer_card_2_text"
            android:layout_
            android:layout_
            android:layout_marginLeft="10dp"
            android:layout_marginTop="3dp"
            android:text="Exchange Rate"
            android:textColor="#878787"
            android:textSize="20dp" />

        <View
            android:layout_
            android:layout_
            android:layout_gravity="bottom"
            android:background="@color/colorPrimary" />

    </com.google.android.material.card.MaterialCardView>

    <com.google.android.material.card.MaterialCardView
        android:id="@+id/materialCardView3"
        style="@style/Widget.MaterialComponents.CardView"
        android:layout_
        android:layout_
        android:layout_marginLeft="@dimen/mtrl_card_spacing"
        android:layout_marginRight="@dimen/mtrl_card_spacing"
        android:layout_marginTop="20dp"
        android:minHeight="100dp"
        app:cardBackgroundColor="#ffffff"
        app:layout_constraintTop_toBottomOf="@+id/materialCardView2">

        <TextView
            android:id="@+id/transfer_card_3_text"
            android:layout_
            android:layout_
            android:layout_marginLeft="10dp"
            android:layout_marginTop="3dp"
            android:text="Exchange Rate"
            android:textColor="#878787"
            android:textSize="20dp" />

        <View
            android:layout_
            android:layout_
            android:layout_gravity="bottom"
            android:background="@color/colorPrimary" />

    </com.google.android.material.card.MaterialCardView>

    <com.google.android.material.card.MaterialCardView
        android:id="@+id/materialCardView4"
        style="@style/Widget.MaterialComponents.CardView"
        android:layout_
        android:layout_
        android:layout_marginLeft="@dimen/mtrl_card_spacing"
        android:layout_marginRight="@dimen/mtrl_card_spacing"
        android:layout_marginTop="20dp"
        android:minHeight="100dp"
        app:cardBackgroundColor="#ffffff"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/materialCardView3">

        <TextView
            android:id="@+id/transfer_card_4_text"
            android:layout_
            android:layout_
            android:layout_marginLeft="10dp"
            android:layout_marginTop="3dp"
            android:text="Exchange Rate"
            android:textColor="#878787"
            android:textSize="20dp" />

        <View
            android:layout_
            android:layout_
            android:layout_gravity="bottom"
            android:background="@color/colorPrimary" />

    </com.google.android.material.card.MaterialCardView>

    <com.google.android.material.card.MaterialCardView
        android:id="@+id/materialCardView5"
        style="@style/Widget.MaterialComponents.CardView"
        android:layout_
        android:layout_
        android:layout_marginLeft="@dimen/mtrl_card_spacing"
        android:layout_marginRight="@dimen/mtrl_card_spacing"
        android:layout_marginTop="20dp"
        android:layout_marginBottom="15dp"
        android:minHeight="100dp"
        app:cardBackgroundColor="#ffffff"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/materialCardView4"
        app:layout_constraintBottom_toBottomOf="parent">

        <TextView
            android:id="@+id/transfer_card_5_text"
            android:layout_
            android:layout_
            android:layout_marginLeft="10dp"
            android:layout_marginTop="3dp"
            android:text="Exchange Rate"
            android:textColor="#878787"
            android:textSize="20dp" />

        <View
            android:layout_
            android:layout_
            android:layout_gravity="bottom"
            android:background="@color/colorPrimary" />

    </com.google.android.material.card.MaterialCardView>
        </androidx.constraintlayout.widget.ConstraintLayout>
    </ScrollView>


</androidx.constraintlayout.widget.ConstraintLayout>

【问题讨论】：

@AndreyStarenky，在片段之间切换时，您是否向 ScrollView 添加了任何新视图？ @PhanVanLinh 不，我 99% 确定我没有添加任何内容。我可能错过了一些非常小的东西，如果我找到任何东西，我会告诉你 【参考方案1】：

我有附在物品上的小吃店。它们在某些情况下工作得很好，但由于某种原因并非总是如此。我认为这可能与 Fragments 在退出时的创建和销毁方式有关。

我用吐司代替了我的小吃店，它解决了这个问题，尽管外观变得更糟了。

【讨论】：

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