layout_constraintLeft_toLeftOf 和 layout_constraintRight_toRightOf 不会使视图与约束一样宽

Question

有两个小部件（在我的示例中为 TextView）。第一个小部件具有固定宽度，第二个小部件应与第一个小部件一样宽。

考虑以下代码片段：

RelativeLayout.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/textView"
        android:layout_width="192dp"
        android:layout_height="wrap_content"
        android:background="#ccc"
        android:text="Short message" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@id/textView"
        android:layout_alignRight="@id/textView"
        android:layout_below="@id/textView"
        android:layout_marginTop="16dp"
        android:background="#aaa"
        android:text="Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book" />
</RelativeLayout>

ConstraintLayout.

<?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"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/textView"
        android:layout_width="192dp"
        android:layout_height="wrap_content"
        android:background="#ccc"
        android:text="Short message" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        android:layout_marginTop="16dp"
        android:background="#aaa"
        android:text="Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book"
        app:layout_constraintLeft_toLeftOf="@+id/textView"
        app:layout_constraintRight_toRightOf="@+id/textView"
        app:layout_constraintTop_toBottomOf="@+id/textView"
        app:layout_constraintHorizontal_bias="0.49" />
</android.support.constraint.ConstraintLayout>

正如您在第二张图片中看到的，第二个小部件没有第一个小部件宽。为什么？我以为 app:layout_constraintLeft_toLeftOf="@+id/textView" app:layout_constraintRight_toRightOf="@+id/textView" 会成功。

Answer 1

尝试将 android:layout_width 设置为 0dp 和 app:layout_constraintWidth_default="wrap"。同时删除左右边距。

Answer 2

按如下方式更改您的第二个 TextView：

<TextView
        android:id="@+id/textView2"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:background="#aaa"
        android:text="Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book"
        app:layout_constraintLeft_toLeftOf="@+id/textView"
        app:layout_constraintRight_toRightOf="@+id/textView"
        app:layout_constraintTop_toBottomOf="@+id/textView"
        app:layout_constraintHorizontal_bias="0.486" />

set layout_width=0 匹配约束，如果要对齐两个textView，则不应设置边距

android:layout_width="0dp"

layout_constraintLeft_toLeftOf 和 layout_constraintRight_toRightOf 不会使视图与约束一样宽

layout_constraintLeft_toLeftOf and layout_constraintRight_toRightOf don't make the view be as wide as the constraint

android

android-layout

android-constraintlayout