layout_constraintLeft_toLeftOf和layout_constraintRight_toRightOf不会使视图像约束一样宽

Question

有两个小部件（在我的示例中为TextView s）。第一个小部件的宽度是固定的，第二个小部件应该和第一个小部件一样宽。

考虑下面的代码片段：

RelativeLayout的。

<?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> 

正如你可以在第二图片中看到，第二小部件不一样宽，第一小。为什么？我以为app:layout_constraintLeft_toLeftOf="@+id/textView" app:layout_constraintRight_toRightOf="@+id/textView"会做到这一点。

Answer 1

更改第二的TextView如下：

<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" /> 

集layout_width = 0匹配的约束，如果要对齐两个TextView的

android:layout_width="0dp" 

你不应该设置margin

Answer 2

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