Question

我学习如何使用ConstraintLayout。并且有问题。

我的activity_test.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"
    android:padding="@dimen/default_padding">

    <RelativeLayout
        android:id="@+id/reserved_layout_search"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="@id/btnScanQRCode"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toLeftOf="@id/btnScanQRCode"
        app:layout_constraintTop_toTopOf="parent">

        <EditText
            android:id="@+id/etSearchWorker"
            style="@style/EditTextSearch"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            />

        <Button
            android:id="@+id/btnClearSearch"
            android:layout_width="32dp"
            android:layout_height="32dp"
            android:layout_alignParentEnd="true"
            android:layout_alignParentRight="true"
            android:layout_centerVertical="true"
            android:background="@drawable/ic_clear"/>

    </RelativeLayout>

    <Button
        android:id="@+id/btnScanQRCode"
        android:layout_width="@dimen/search_qr_button_size"
        android:layout_height="@dimen/search_qr_button_size"
        android:background="@drawable/button_qr_background"
        android:text="@string/button_qr_text"
        android:textColor="@color/white"
        app:layout_constraintLeft_toRightOf="@id/reserved_layout_search"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>

    <TextView
        android:id="@+id/tvPlanningCountInfo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:text="ddsadsas"
        app:layout_constraintHorizontal_chainStyle="spread"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toLeftOf="@id/tvReservedContInfo"
        app:layout_constraintTop_toBottomOf="@id/btnScanQRCode"
        />

    <TextView
        android:id="@+id/tvReservedContInfo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="dsdsadasdasad :44"
        app:layout_constraintLeft_toRightOf="@id/tvPlanningCountInfo"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="@id/tvPlanningCountInfo"
        />

    <android.support.v7.widget.RecyclerView
        android:id="@+id/rvReserved"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginTop="@dimen/default_padding"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@id/tvPlanningCountInfo"
        app:layout_constraintBottom_toBottomOf="parent"
        />

</android.support.constraint.ConstraintLayout>

当我构建/重建/清理项目时，我处理错误：

/Users/ME/Documents/Projects/testApp/app/src/main/res/layout/activity_test.xml
Error:(14, 49) No resource found that matches the given name (at 'layout_constraintBottom_toBottomOf' with value '@id/btnScanQRCode').
Error:(16, 46) No resource found that matches the given name (at 'layout_constraintRight_toLeftOf' with value '@id/btnScanQRCode').
Error:(56, 46) No resource found that matches the given name (at 'layout_constraintRight_toLeftOf' with value '@id/tvReservedContInfo').

可能是什么问题？也许有可能更好地编写这段代码？

但预览有效：

Answer 1

您正在尝试在定义约束之前基于元素设置约束。因此，要解决您的问题，您有两种不同的方式：

第一个解决方案：将您的RelativeLayout（@ + id / reserved_layout_search）约束ID值替换为：

@id/btnScanQRCode -> @+id/btnScanQRCode
@id/btnScanQRCode -> @+id/btnScanQRCode
@id/tvReservedContInfo -> @+id/tvReservedContInfo

第二个解决方案：在XML文件的RelativeLayout之前声明你的btnScanQRCode，btnScanQRCode和tvReservedContInfo小部件。

Answer 2

只需将（@id/btnScanQRCode和@id/tvReservedContInfo）替换为（@+id/btnScanQRCode和@+id/tvReservedContInfo）。

试试这个：

<?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"
    android:padding="@dimen/default_padding">

    <RelativeLayout
        android:id="@+id/reserved_layout_search"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="@+id/btnScanQRCode"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toLeftOf="@+id/btnScanQRCode"
        app:layout_constraintTop_toTopOf="parent">

        <EditText
            android:id="@+id/etSearchWorker"
            style="@style/EditTextSearch"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            />

        <Button
            android:id="@+id/btnClearSearch"
            android:layout_width="32dp"
            android:layout_height="32dp"
            android:layout_alignParentEnd="true"
            android:layout_alignParentRight="true"
            android:layout_centerVertical="true"
            android:background="@drawable/ic_clear"/>

    </RelativeLayout>

    <Button
        android:id="@+id/btnScanQRCode"
        android:layout_width="@dimen/search_qr_button_size"
        android:layout_height="@dimen/search_qr_button_size"
        android:background="@drawable/button_qr_background"
        android:text="@string/button_qr_text"
        android:textColor="@color/white"
        app:layout_constraintLeft_toRightOf="@+id/reserved_layout_search"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>

    <TextView
        android:id="@+id/tvPlanningCountInfo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:text="ddsadsas"
        app:layout_constraintHorizontal_chainStyle="spread"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toLeftOf="@+id/tvReservedContInfo"
        app:layout_constraintTop_toBottomOf="@+id/btnScanQRCode"
        />

    <TextView
        android:id="@+id/tvReservedContInfo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="dsdsadasdasad :44"
        app:layout_constraintLeft_toRightOf="@id/tvPlanningCountInfo"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="@id/tvPlanningCountInfo"
        />

    <android.support.v7.widget.RecyclerView
        android:id="@+id/rvReserved"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginTop="@dimen/default_padding"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@id/tvPlanningCountInfo"
        app:layout_constraintBottom_toBottomOf="parent"
        />

</android.support.constraint.ConstraintLayout>

ConstraintLayout出错：找不到与给定名称匹配的资源

2 个答案: