Android – How to Change the Color of Alternate Rows in RecyclerView
Last Updated :
03 Apr, 2023
RecyclerView is an essential ViewGroup used in Android to display a list of items. It provides a flexible and highly customizable way of implementing a list that can be presented as a grid or a list. In this project, we will be working with RecyclerView to change the color of alternate rows. Typically, all items in a RecyclerView have the same color, which can be monotonous and unappealing. By alternating the row colors, we can provide a better visual experience to the user. To achieve this, we will assign a LightGrey color to the items at even positions and a White color to those at odd positions. This simple trick will help us customize our RecyclerView and enhance the user interface. The image below illustrates what we will accomplish in this project.
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. Note that select Kotlin as the programming language.
Step 2: Add buildFeatures to build.gradle (Module:app)
Since in this project, we used ViewBinding so we have to set ViewBinding=True. Navigate to Gradle Scripts > build.gradle (Module:app) and add the Below buildFeatures section under the android section in the build.gradle (Module:app).
buildFeatures
{
viewBinding = true
}
Android Section
android {
namespace 'com.example.geeksforgeeks'
compileSdk 32
defaultConfig {
applicationId "com.example.geeksforgeeks"
minSdk 21
targetSdk 32
versionCode 1
versionName "1.0"
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}
}
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}
kotlinOptions {
jvmTarget = '1.8'
}
buildFeatures {
viewBinding = true
}
}
After adding this buildFeatures section, Sync the Project.
Step 3: Change the StatusBar Color
Navigate to app > res > values > themes > themes.xml and add the below code under the style section in the themes.xml file.
<item name="android:statusBarColor" tools:targetApi="l">#308d46</item>
Step 4: Working with activity_main.xml
Navigate to the app > res > layout > activity_main.xml and add the below code to the activity_main.xml file. Below is the code for the activity_main.xml file. The activity_main.xml represents the UI part of our application. It includes one RecyclerView on which our list of items is displayed. Comments are added inside the code for a better understanding of the Code.
XML
<? xml version = "1.0" encoding = "utf-8" ?>
< androidx.constraintlayout.widget.ConstraintLayout
android:layout_width = "match_parent"
android:layout_height = "match_parent"
tools:context = ".MainActivity" >
< androidx.recyclerview.widget.RecyclerView
android:layout_width = "match_parent"
android:layout_height = "match_parent"
android:id = "@+id/rvItemsList" />
</ androidx.constraintlayout.widget.ConstraintLayout >
|
Step 5: Creating a layout for RecyclerView
Here we have to create a layout for our RecyclerView to display our items. Navigate to app > res > layout then Create a new layout resource file and name it items_row.xml. It includes three Text Views for displaying the Name and Emails of the Employees. Comments are added inside the code for a better understanding of the Code.
items_row.xml:
XML
<? xml version = "1.0" encoding = "utf-8" ?>
< LinearLayout
android:id = "@+id/llMain"
android:layout_width = "match_parent"
android:layout_height = "wrap_content"
android:gravity = "center_vertical"
android:orientation = "horizontal"
android:padding = "10dp" >
< TextView
android:id = "@+id/tvName"
android:layout_width = "wrap_content"
android:layout_height = "wrap_content"
android:textColor = "@android:color/black"
android:textSize = "20sp"
tools:text = "Name" />
< TextView
android:layout_width = "wrap_content"
android:layout_height = "wrap_content"
android:text = " : "
android:textSize = "20dp"
android:textStyle = "bold" />
< TextView
android:id = "@+id/tvEmail"
android:layout_width = "0dp"
android:layout_height = "wrap_content"
android:layout_weight = "1"
android:textColor = "#454545"
android:textSize = "16sp"
tools:text = "Email" />
</ LinearLayout >
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Step 6: Creating Employee Model
In this step, we are going to create an employee model for our RecyclerView. It Contains the Employee’s Name and Employee email Id. Below is the code for the Employee model. Navigate to app >java > your package name > Create a Kotlin data class named it Employee.kt.
Employee.kt:
Kotlin
package com.example.geeksforgeeks
data class Employee(
val name:String,
val email:String
)
|
Java
package com.example.geeksforgeeks;
public class Employee {
private String name;
private String email;
public Employee(String name, String email) {
this .name = name;
this .email = email;
}
public String getName() {
return name;
}
public String getEmail() {
return email;
}
public void setName(String name) {
this .name = name;
}
public void setEmail(String email) {
this .email = email;
}
}
|
Step 7: Creating Employee ArrayList
In this step, we are going to prepare the List of employees with the employee name and employee email. Below is the code for Creating and adding data to the ArrayList. Comments are added inside the code for a better understanding of the Code. Navigate to app > java >your package name > Create a Kotlin Object named Constants.
Constants.kt:
Kotlin
package com.example.geeksforgeeks
object Constants {
fun getEmployeeData():ArrayList<Employee>{
val employeeList=ArrayList<Employee>()
val emp1=Employee( "Chinmaya Mohapatra" , "chinmaya@gmail.com" )
employeeList.add(emp1)
val emp2=Employee( "Ram prakash" , "ramp@gmail.com" )
employeeList.add(emp2)
val emp3=Employee( "OMM Meheta" , "mehetaom@gmail.com" )
employeeList.add(emp3)
val emp4=Employee( "Hari Mohapatra" , "harim@gmail.com" )
employeeList.add(emp4)
val emp5=Employee( "Abhisek Mishra" , "mishraabhi@gmail.com" )
employeeList.add(emp5)
val emp6=Employee( "Sindhu Malhotra" , "sindhu@gmail.com" )
employeeList.add(emp6)
return employeeList
}
}
|
Java
package com.example.geeksforgeeks;
import java.util.ArrayList;
public class Constants {
public static ArrayList<Employee> getEmployeeData() {
ArrayList<Employee> employeeList = new ArrayList<Employee>();
Employee emp1 = new Employee( "Chinmaya Mohapatra" , "chinmaya@gmail.com" );
employeeList.add(emp1);
Employee emp2 = new Employee( "Ram prakash" , "ramp@gmail.com" );
employeeList.add(emp2);
Employee emp3 = new Employee( "OMM Meheta" , "mehetaom@gmail.com" );
employeeList.add(emp3);
Employee emp4 = new Employee( "Hari Mohapatra" , "harim@gmail.com" );
employeeList.add(emp4);
Employee emp5 = new Employee( "Abhisek Mishra" , "mishraabhi@gmail.com" );
employeeList.add(emp5);
Employee emp6 = new Employee( "Sindhu Malhotra" , "sindhu@gmail.com" );
employeeList.add(emp6);
return employeeList;
}
}
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Step 8: Creating Adapter for our RecyclerView
As we know for every RecycleView we need an Adapter class. and Implement the Three member functions.
- onCreateViewHolder: Here we have to connect the layout resource file that we are for our RecyclerView.
- onBindViewHolder: Here we have to bind our items to the data source.
- getItemCount: Here we have to return the length of our ArrayList
Here we are going to implement the main logic to change the color of the alternate Row item. In the onBindViewHolder method we are going to check if the position is Even we assign Light grey color to that item and if the position is odd then we going to assign a white color to the item.
if (position % 2 == 0) {
holder.llMain.setBackgroundColor(
ContextCompat.getColor(
holder.itemView.context,
R.color.colorLightGray
)
)
} else {
holder.llMain.setBackgroundColor(ContextCompat.getColor(context, R.color.colorWhite))
}
Navigate to app > java >your package name > Create a Kotlin Object named as ItemAdapter.Below is the code for the ItemAdapter class. Comments are added inside the code for a better understanding of the Code.
ItemAdapter.kt:
Kotlin
package com.example.geeksforgeeks
import android.view.LayoutInflater
import android.view.ViewGroup
import androidx.core.content.ContextCompat
import androidx.recyclerview.widget.RecyclerView
import com.example.geeksforgeeks.databinding.ItemsRowBinding
class ItemAdapter(
private val items: ArrayList<Employee>
) :
RecyclerView.Adapter<ItemAdapter.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
return ViewHolder(
ItemsRowBinding.inflate(
LayoutInflater.from(parent.context), parent, false
)
)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val context = holder.itemView.context
val item = items[position]
holder.tvName.text = item.name
holder.tvEmail.text = item.email
if (position % 2 == 0 ) {
holder.llMain.setBackgroundColor(
ContextCompat.getColor(
holder.itemView.context,
R.color.colorLightGray
)
)
} else {
holder.llMain.setBackgroundColor(ContextCompat.getColor(context, R.color.colorWhite))
}
}
override fun getItemCount(): Int {
return items.size
}
class ViewHolder(binding: ItemsRowBinding) : RecyclerView.ViewHolder(binding.root) {
val llMain = binding.llMain
val tvName = binding.tvName
val tvEmail = binding.tvEmail
}
}
|
Java
package com.example.geeksforgeeks;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import androidx.core.content.ContextCompat;
import androidx.recyclerview.widget.RecyclerView;
import com.example.geeksforgeeks.databinding.ItemsRowBinding;
import java.util.ArrayList;
public class ItemAdapter extends RecyclerView.Adapter<ItemAdapter.ViewHolder> {
private ArrayList<Employee> items;
public ItemAdapter(ArrayList<Employee> items) {
this .items = items;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
return new ViewHolder(
ItemsRowBinding.inflate(
LayoutInflater.from(parent.getContext()), parent, false
)
);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Context context = holder.itemView.getContext();
Employee item = items.get(position);
holder.tvName.setText(item.getName());
holder.tvEmail.setText(item.getEmail());
if (position % 2 == 0 ) {
holder.llMain.setBackgroundColor(
ContextCompat.getColor(
holder.itemView.getContext(),
R.color.colorLightGray
)
);
} else {
holder.llMain.setBackgroundColor(ContextCompat.getColor(context, R.color.colorWhite));
}
}
@Override
public int getItemCount() {
return items.size();
}
public static class ViewHolder extends RecyclerView.ViewHolder {
private final ViewGroup llMain;
private final TextView tvName;
private final TextView tvEmail;
public ViewHolder(ItemsRowBinding binding) {
super (binding.getRoot());
llMain = binding.llMain;
tvName = binding.tvName;
tvEmail = binding.tvEmail;
}
}
}
|
Step 9: Working with MainActivity File
In this step, we are going to Get the employeelist by calling the Constants getEmployeeData() method and assign the employee list to the ItemAdapter and display the employee list.
MainActivity.kt:
Kotlin
package com.example.geeksforgeeks
import android.Manifest
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import androidx.activity.result.ActivityResultLauncher
import androidx.activity.result.contract.ActivityResultContracts
import androidx.appcompat.app.AlertDialog
import androidx.core.app.ActivityCompat
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.geeksforgeeks.databinding.ActivityMainBinding
class MainActivity : AppCompatActivity() {
var binding:ActivityMainBinding?= null
override fun onCreate(savedInstanceState: Bundle?) {
super .onCreate(savedInstanceState)
binding=ActivityMainBinding.inflate(layoutInflater)
setContentView(binding?.root)
val employelist=Constants.getEmployeeData()
val itemAdapter=ItemAdapter(employelist)
binding?.rvItemsList?.layoutManager = LinearLayoutManager( this )
binding?.rvItemsList?.adapter = itemAdapter
}
}
|
Java
package com.example.geeksforgeeks;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.recyclerview.widget.LinearLayoutManager;
import android.Manifest;
import android.os.Bundle;
import android.widget.Toast;
import com.example.geeksforgeeks.databinding.ActivityMainBinding;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
private ActivityMainBinding binding;
@Override
protected void onCreate(Bundle savedInstanceState) {
super .onCreate(savedInstanceState);
binding = ActivityMainBinding.inflate(getLayoutInflater());
setContentView(binding.getRoot());
ArrayList<Employee> employelist = Constants.getEmployeeData();
ItemAdapter itemAdapter = new ItemAdapter(employelist);
binding.rvItemsList.setLayoutManager( new LinearLayoutManager( this ));
binding.rvItemsList.setAdapter(itemAdapter);
}
}
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Output:
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