Fill whole screen with four buttons by two rows in Android

Question

I want to fill the whole screen with four buttons that has the same width and height so I thought a grid layout would be a great idea:

<GridLayout
    android:id="@+id/grid"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:columnCount="2"
    android:rowCount="2"
    >

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button"
        android:layout_columnWeight="1"
        android:layout_rowWeight="0"
        />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button"
        android:layout_columnWeight="1"
        android:layout_rowWeight="0"
        />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button"
        android:layout_rowWeight="1"
        android:layout_columnWeight="1"
        />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button"
        android:layout_rowWeight="1"
        android:layout_columnWeight="1"
        />

</GridLayout>

Unfortunatly my result looks like this:

I don't understand why the height of the second row is so big?
I thought every cell in a grid layout got the same width and height!

Answer 1

This can also be done with ConstraintLayout, which will give you a flat hierarchy and more flexibility for future changes.

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

    <Button
        android:id="@+id/button"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:text="Button"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/button2"
        app:layout_constraintBottom_toTopOf="@id/button3"/>

    <Button
        android:id="@+id/button2"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:text="Button"
        app:layout_constraintStart_toEndOf="@+id/button"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toTopOf="@+id/button4" />

    <Button
        android:id="@+id/button3"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:text="Button"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/button4"
        app:layout_constraintTop_toBottomOf="@+id/button" />

    <Button
        android:id="@+id/button4"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:text="Button"
        app:layout_constraintTop_toBottomOf="@id/button2"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/button3"/>
</android.support.constraint.ConstraintLayout>