Android Constraint layout, views with weight?

Question

So like the picture below, I want view B be twice the length of view A.

What I exactly need is view A sticks to the left edge, view B sticks to the right edge and they stick to each other in between. And in the length, the B is going to be twice the length of A. I tried a lot, but no luck! in the end, something is not what I want. Either there is unwanted space between a view and its according edge or between the two views.

Here is my last try:

<?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="10dp"
tools:context=".MainActivity">

<EditText
    android:id="@+id/editText"
    android:layout_width="wrap_content"
    android:layout_height="50dp"
    android:layout_marginTop="36dp"
    android:ems="10"
    android:text="B"
    android:inputType="textPersonName"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_weight="2"
    app:layout_constraintStart_toEndOf="@+id/textView"
    app:layout_constraintTop_toTopOf="parent" />


<TextView
    android:id="@+id/textView"
    android:layout_width="wrap_content"
    android:layout_height="50dp"
    android:layout_marginTop="36dp"
    android:gravity="center"
    android:text="A"
    app:layout_constraintHorizontal_weight="1"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

Answer 1

You can use app:layout_constraintWidth_percent ti tell your view how to spread on the screen.

For your wanted look you can use it like this:

<?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">


<Button
    android:id="@+id/button"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:text="Button"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toStartOf="@+id/button2"
    app:layout_constraintWidth_percent=".33"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

<Button
    android:id="@+id/button2"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:text="Button"
    app:layout_constraintBottom_toBottomOf="@+id/button"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintWidth_percent=".66"
    app:layout_constraintStart_toEndOf="@+id/button"
    app:layout_constraintTop_toTopOf="@+id/button" />
</android.support.constraint.ConstraintLayout>

It will look like this

Answer 2

To use layout_constraintHorizontal_weight, you have to put your Views in a chain first. That means you have to constraint both Views to each other and the parent horizontally. What you are missing in your case is the app:layout_constraintEnd_toStartOf="@id/editText" on the TextView. You also need to change the android:layout_width of both Views to 0dp so that the weight is enforced:

<?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="10dp"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/editText"
        android:layout_width="0dp"
        android:layout_height="50dp"
        android:layout_marginTop="36dp"
        android:ems="10"
        android:text="B"
        android:inputType="textPersonName"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_weight="2"
        app:layout_constraintStart_toEndOf="@+id/textView"
        app:layout_constraintTop_toTopOf="parent" />


    <TextView
        android:id="@+id/textView"
        android:layout_width="0dp"
        android:layout_height="50dp"
        android:layout_marginTop="36dp"
        android:gravity="center"
        android:text="A"
        app:layout_constraintHorizontal_weight="1"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toStartOf="@id/editText"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>