How to change button size according to screen's device?

Question

I have a button with size width=216 and height=110 in a device screen resolution is 1080 x 1920. When I change to other device (smaller resolution), the button is so big. Hence, I need to write a fuction to dynamically change button size according to screen's device resolution. First, I will check target device resolution then I change it based on above my current device. However, the button resolution is not correct. How can I fix it? This is my code

My code in the 1080x1920

        <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_gravity="center"
        >
        <Button
            android:id="@+id/btn"
            android:layout_width="216dp"
            android:layout_height="110dp"
            android:layout_gravity="center"
            android:scaleType="fitCenter"
          />
       </LinearLayout>

Changed to dynamic way:

    public int WIDTH ;
    public int HEIGHT ;
    //Get screen resolution
    DisplayMetrics metrics = getResources().getDisplayMetrics();
    HEIGHT = metrics.heightPixels;
    WIDTH= metrics.widthPixels;           

    int height_px = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 110, getResources().getDisplayMetrics());
    int weight_px = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 216, getResources().getDisplayMetrics());
    int width_linearlayout = Math.round((float)weight_px/1080*WIDTH);
    int height_linearlayout = Math.round((float)height_px/1920*HEIGHT);
    LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(width_linearlayout,height_linearlayout);
    btn.setLayoutParams(layoutParams);

Answer 1

What I would do in situations like this is create a specific dimens.xml for different screen size requirements.

Each of these would contain parameters specific to devices with screens fitting those dimensions.

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <!-- Default screen margins, per the Android Design guidelines. -->
  <dimen name="nav_header_height">160dp</dimen>
  <!-- Default screen margins, per the Android Design guidelines. -->
  <dimen name="activity_horizontal_margin">16dp</dimen>
  <dimen name="activity_vertical_margin">16dp</dimen>
  <dimen name="button_size_height">32dp</dimen>
  <dimen name="button_size_width">70dp</dimen>
</resources>

No Extra coding, just need to maintain multiple xml files containing your button parameters.

Each dimension would be referenced as such:

<Button
            android:id="@+id/btn"
            android:layout_width="@dimen/button_size_width"
            android:layout_height="@dimen/button_size_height"
            android:layout_gravity="center"
            android:scaleType="fitCenter"
          />

Answer 2

You have to use layout_weight in order to achieve what you want, and that will be used by wrapping each row of buttons inside a LinearLayout and all that LinearLayouts plus the TextView will be wrapped inside one big LinearLayout instead of your RelativeLayout like the following:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/main_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ff000000"
    android:orientation="vertical"
    android:weightSum="6" >

<TextView
    android:id="@+id/disp"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1"
    android:gravity="center"
    android:inputType="none"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:textColor="@android:color/white"
    android:textSize="32sp"
    android:textStyle="normal" />

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1"
    android:orientation="horizontal"
    android:weightSum="4" >

    <Button
        android:id="@+id/clear"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="4"
        android:background="@drawable/clear_btn" />

    <!-- then the three remaining buttons -->

    <LinearLayout />

    <!-- then the four remaining rows -->


    <!-- in the last row the "0" button will have layout_weight="2" NOT "1" -->
</LinearLayout>

Answer 3

Add folder values-sw540dp its is for 1080p screens . In this folder add dimens.xml

  <dimen name="btn_height">100dp</dimen>
  <dimen name="btn_width">65dp</dimen>

Edit your xml

<LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_gravity="center"
        >
        <Button
            android:id="@+id/btn"
            android:layout_width="@dimen/btn_width"
            android:layout_height="@dimen/btn_height"
            android:layout_gravity="center"
            android:scaleType="fitCenter"
          />
       </LinearLayout>

Other resolutions

    values-sw720dp          10.1” tablet 1280x800 mdpi

values-sw600dp          7.0”  tablet 1024x600 mdpi

values-sw480dp          5.4”  480x854 mdpi 
values-sw480dp          5.1”  480x800 mdpi 

values-xhdpi            4.7”   1280x720 xhdpi 
values-xhdpi            4.65”  720x1280 xhdpi 

values-hdpi             4.0” 480x800 hdpi
values-hdpi             3.7” 480x854 hdpi

values-mdpi             3.2” 320x480 mdpi

values-ldpi             3.4” 240x432 ldpi
values-ldpi             3.3” 240x400 ldpi
values-ldpi             2.7” 240x320 ldpi