layout_constraintLeft_toLeftOf和layout_constraintRight_toRightOf不會使視圖像約束一樣寬

Question

有兩個小部件（在我的示例中爲TextView s）。第一個小部件的寬度是固定的，第二個小部件應該和第一個小部件一樣寬。

考慮下面的代碼片段：

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> 

正如你可以在第二圖片中看到，第二小部件不一樣寬，第一小。爲什麼？我以爲app:layout_constraintLeft_toLeftOf="@+id/textView" app:layout_constraintRight_toRightOf="@+id/textView"會做到這一點。

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匹配的約束，如果要對齊兩個TextView的

android:layout_width="0dp" 

你不應該設置margin

Answer 2

嘗試設置android:layout_width爲0dp 和app:layout_constraintWidth_default="wrap"。同時刪除左右邊距。