Expandable Cardview provides to create expansion panels without too much hassle and without writing boilerplate code. An expandable card view becomes quite useful when it comes to an efficient and systematic presentation of data or information on the screen. It is used in a variety of apps, for example, the Contacts app or the Gallery app. We are going to implement this project using both Java and Kotlin Programming Languages for Android.
Step by Step Implementation
Step 1: Create a New Project in Android Studio
To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. The code for that has been given in both Java and Kotlin Programming Language for Android.
Step 2: Adding Dependency to the build.gradle File
Go to Module build.gradle file and add this dependency and click on Sync Now button.
implementation 'androidx.cardView:cardView:1.0.0'
Step 3: Add all the Required Drawable Resources to the Drawable Folder
Choose the drawable resources as per the requirement. Here, in the CardView, use two images of the Lazyroar icons and 2 other icons to indicate either of the ‘expand more’ or ‘expand less’ options.
The following are the Lazyroar icons used:
The image below shows the use of expansion icons:
The expansion icons used here are imported as a vector asset from the Android Studio itself. The steps for the same are as follows:
Right-click on the drawable resource folder > Go to new > Click on Vector Asset > The following box pops up > Click on the icon next to Clip Art
From the variety of icons shown, choose the following two icons:
ic_baseline_expand_more_24 ic_baseline_expand_less_24
Step 4: Working with the XML Files
In the XML file, create the entire layout along with the portion that you want to be displayed after the CardView is expanded. The basic idea here is to set the visibility of the expandable element to ‘gone’ or ‘visible’.
Note: Set the visibility to ‘gone’ and not ‘invisible’ because ‘gone’ removes that particular element completely as if it was never there. However, ‘invisible’ only makes the element disappears while it still exists in the layout.
Next, go to the activity_main.xml file, which represents the UI of the project. Below is the code for the activity_main.xml file. Comments are added inside the code to understand the code in more detail.
XML
<?xml version="1.0" encoding="utf-8"?><androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#E4E3E3" tools:context=".MainActivity"> <!-- Base CardView --> <androidx.cardview.widget.CardView android:id="@+id/base_cardview" style="@style/Base.CardView" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_margin="10dp" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.473" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" app:layout_constraintVertical_bias="0.021"> <!-- This is a ConstraintLayout for the entire CardView including the expandable portion --> <androidx.constraintlayout.widget.ConstraintLayout android:layout_width="match_parent" android:layout_height="wrap_content" app:layout_constraintBottom_toBottomOf="@+id/base_cardview" app:layout_constraintTop_toTopOf="parent" app:layout_constraintVertical_bias="0.511" tools:layout_editor_absoluteX="-55dp"> <!-- This is a ConstraintLayout for the fixed portion of the CardView. The elements that lie within the fixed portion of the CardView can be constrained to this layout --> <androidx.constraintlayout.widget.ConstraintLayout android:id="@+id/fixed_layout" android:layout_width="match_parent" android:layout_height="150dp" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.0" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" app:layout_constraintVertical_bias="0.0"> <ImageView android:id="@+id/icon" android:layout_width="150dp" android:layout_height="150dp" android:src="@drawable/icon_one" app:layout_constraintBottom_toBottomOf="@+id/fixed_layout" app:layout_constraintEnd_toEndOf="@+id/fixed_layout" app:layout_constraintHorizontal_bias="0.0" app:layout_constraintStart_toStartOf="@+id/fixed_layout" app:layout_constraintTop_toTopOf="@+id/fixed_layout" app:layout_constraintVertical_bias="1.0" /> <TextView android:id="@+id/heading" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Lazyroar" android:textColor="#006600" android:textSize="25dp" android:textStyle="bold" app:layout_constraintBottom_toBottomOf="@+id/fixed_layout" app:layout_constraintEnd_toEndOf="@+id/fixed_layout" app:layout_constraintHorizontal_bias="0.926" app:layout_constraintStart_toStartOf="@+id/fixed_layout" app:layout_constraintTop_toTopOf="@+id/fixed_layout" app:layout_constraintVertical_bias="0.198" /> <TextView android:id="@+id/list_of_subjects" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginTop="20dp" android:layout_marginBottom="58dp" android:text="List of subjects" android:textSize="20dp" app:layout_constraintBottom_toBottomOf="@+id/fixed_layout" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.878" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/heading" app:layout_constraintVertical_bias="0.0" /> <!-- This is ImageButton for the expansion icon --> <ImageButton android:id="@+id/arrow_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/ic_baseline_expand_more_24" app:layout_constraintBottom_toBottomOf="@id/fixed_layout" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.802" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/list_of_subjects" app:layout_constraintVertical_bias="0.0" /> </androidx.constraintlayout.widget.ConstraintLayout> <!-- The following is the expandable portion whose visibility is initially set to 'gone' The parent LinearLayout contains 3 child LinearLayouts that hold a subject name and an icon each --> <LinearLayout android:id="@+id/hidden_view" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" android:visibility="gone" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/fixed_layout"> <!-- Child LinearLayout 1 --> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="horizontal"> <ImageView android:layout_width="50dp" android:layout_height="50dp" android:layout_marginStart="20dp" android:layout_marginTop="10dp" android:layout_marginEnd="10dp" android:layout_marginBottom="10dp" android:src="@drawable/gfg_icon_black" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="20dp" android:layout_marginTop="20dp" android:text="Database Management" android:textColor="#000000" android:textSize="20dp" /> </LinearLayout> <!-- Child LinearLayout 2 --> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="horizontal"> <ImageView android:layout_width="50dp" android:layout_height="50dp" android:layout_marginStart="20dp" android:layout_marginTop="10dp" android:layout_marginEnd="10dp" android:layout_marginBottom="10dp" android:src="@drawable/gfg_icon_black" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="20dp" android:layout_marginTop="20dp" android:text="Data Structures" android:textColor="#000000" android:textSize="20dp" /> </LinearLayout> <!-- Child LinearLayout 3 --> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="horizontal"> <ImageView android:layout_width="50dp" android:layout_height="50dp" android:layout_marginStart="20dp" android:layout_marginTop="10dp" android:layout_marginEnd="10dp" android:layout_marginBottom="10dp" android:src="@drawable/gfg_icon_black" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="20dp" android:layout_marginTop="20dp" android:text="Operating Systems" android:textColor="#000000" android:textSize="20dp" /> </LinearLayout> </LinearLayout> </androidx.constraintlayout.widget.ConstraintLayout> </androidx.cardview.widget.CardView></androidx.constraintlayout.widget.ConstraintLayout> |
Step 5: Working with the MainActivity File
Go to the MainActivity File and refer to the following code. Below is the code for the MainActivity File. Comments are added inside the code to understand the code in more detail.
Java
import android.os.Bundle;import android.transition.AutoTransition;import android.transition.TransitionManager;import android.view.View;import android.widget.ImageButton;import android.widget.LinearLayout;import androidx.appcompat.app.AppCompatActivity;import androidx.cardview.widget.CardView; public class MainActivity extends AppCompatActivity { ImageButton arrow; LinearLayout hiddenView; CardView cardView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); cardView = findViewById(R.id.base_cardview); arrow = findViewById(R.id.arrow_button); hiddenView = findViewById(R.id.hidden_view); arrow.setOnClickListener(view -> { // If the CardView is already expanded, set its visibility // to gone and change the expand less icon to expand more. if (hiddenView.getVisibility() == View.VISIBLE) { // The transition of the hiddenView is carried out by the TransitionManager class. // Here we use an object of the AutoTransition Class to create a default transition TransitionManager.beginDelayedTransition(cardView, new AutoTransition()); hiddenView.setVisibility(View.GONE); arrow.setImageResource(R.drawable.ic_baseline_expand_more_24); } // If the CardView is not expanded, set its visibility to // visible and change the expand more icon to expand less. else { TransitionManager.beginDelayedTransition(cardView, new AutoTransition()); hiddenView.setVisibility(View.VISIBLE); arrow.setImageResource(R.drawable.ic_baseline_expand_less_24); } }); }} |
Kotlin
import android.os.Buildimport android.os.Bundleimport android.transition.AutoTransitionimport android.transition.TransitionManagerimport android.view.Viewimport android.widget.ImageButtonimport android.widget.LinearLayoutimport androidx.appcompat.app.AppCompatActivityimport androidx.cardview.widget.CardView class MainActivity : AppCompatActivity() { private lateinit var arrow: ImageButton private lateinit var hiddenView: LinearLayout private lateinit var cardView: CardView override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) cardView = findViewById(R.id.base_cardview) arrow = findViewById(R.id.arrow_button) hiddenView = findViewById(R.id.hidden_view) arrow.setOnClickListener { // If the CardView is already expanded, set its visibility // to gone and change the expand less icon to expand more. if (hiddenView.visibility == View.VISIBLE) { // The transition of the hiddenView is carried out by the TransitionManager class. // Here we use an object of the AutoTransition Class to create a default transition if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) { TransitionManager.beginDelayedTransition(cardView, AutoTransition()) } hiddenView.visibility = View.GONE arrow.setImageResource(R.drawable.ic_baseline_expand_more_24) } else { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) { TransitionManager.beginDelayedTransition(cardView, AutoTransition()) } hiddenView.visibility = View.VISIBLE arrow.setImageResource(R.drawable.ic_baseline_expand_less_24) } } }} |
