styles.xml无法正常工作

Question

Context:

I recently started trying to learn how to develop very simple Android apps, and have been following many different tutorials and resources available online. I was looking at an exercise that showed how you can use additional xml files, such as styles.xml to apply a certain style to something without having to copy and paste the same code in the main.axml multiple times. So for example, if you have many Buttons, you can apply one general style to all those buttons.

Problem: I have created this app that does nothing, I just wanted to experiment with combing layouts and getting a feel for things. It has 4 buttons (that don't click as yet). This is how it looks, followed by the main.axml code.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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">
    <HorizontalScrollView
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">
        <TextView
            android:id="@+id/calculator_text_view"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:padding="10dp"
            android:textSize="50sp"
            android:text="0" />
    </HorizontalScrollView>
    <GridLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="4"
        android:columnCount="2"
        android:rowCount="3">
        <Button
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:background="#ff3f51b5"
            android:textSize="25sp"
            android:text="1st"
            android:onClick="ButtonClick" />
        <Button
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:background="#F44336"
            android:textSize="25sp"
            android:text="2nd"
            android:onClick="ButtonClick" />
        <Button
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:background="#ff9c27b0"
            android:textSize="25sp"
            android:text="3rd"
            android:onClick="ButtonClick" />
        <Button
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:background="#ff4caf50"
            android:textSize="25sp"
            android:text="4th"
            android:onClick="ButtonClick" />
    </GridLayout>
</LinearLayout>

Now I tried applying a 'style' to the buttons because they have a lot of the same properties, and it will make the code simpler and easier to read. This is how I applied the style:

<Button
   style="@style/button_style"
   android:background="#ff3f51b5"
   android:text="1st"/>
<Button
   style="@style/button_style"
   android:background="#F44336"
   android:text="2nd"/>
<Button
   style="@style/button_style"
   android:background="#ff9c27b0"
   android:text="3rd"/>
<Button
   style="@style/button_style"
   android:background="#ff4caf50"
   android:text="4th"/>

And this is what's in styles.xml :

  <!-- Base application theme. -->
  <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
  </style>

  <style name="button_style">
    <item name="android:layout_width">0dp</item>
    <item name="android:layout_height">0dp</item>
    <item name="android:layout_rowWeight">1</item>
    <item name="android:layout_columnWeight">1</item>
    <item name="android:textSize">25dp</item>
    <item name="android:onClick">ButtonClick</item>
  </style>
</resources>

And finally how the UI looks. As evident, none of the button attributes from styles got carried over :

I can't seem to figure out what I'm doing wrong. I know I probably won't ever need to do this with buttons but I guess it could be helpful for something else later on.

Answer 1

Make your button_style extend as

 parent="Widget.AppCompat.Button"

full style would be

<style name="button_style" parent="Widget.AppCompat.Button">
<item name="android:layout_width">0dp</item>
<item name="android:layout_height">0dp</item>
<item name="android:layout_rowWeight">1</item>
<item name="android:layout_columnWeight">1</item>
<item name="android:textSize">25dp</item>

</style>