What are Threads in Android with Example?
Last Updated :
06 Feb, 2023
In Android, a thread is a background process that can run independently of the main UI thread. In Java and Kotlin, the Thread class and coroutines can be used to create and manage threads.
Kotlin
Java
Thread thread = new Thread( new Runnable() {
@Override public void run() {
}
});
thread.start();
|
Note: It’s recommended to use coroutines in Kotlin instead of Thread, as they are more lightweight and easier to manage.
Code Snippet of a function that uses coroutines to perform a network request in the background, and updates the UI with the result:
fun doNetworkRequest() = GlobalScope.launch(Dispatchers.Main) {
val result = withContext(Dispatchers.IO) {
// perform network request
}
// update UI with the result
}
There are different types of threads in Android, each with its own use cases:
- The main thread, also known as the UI thread, is responsible for handling all UI updates and user interactions. Any code that updates the UI or interacts with the user should be run on the main thread.
- Worker threads are used for background tasks that should not block the main thread, such as network requests, database operations, and image processing.
- AsyncTask is a helper class that allows you to perform background tasks and update the UI from the same thread. However, it has some limitations and it’s recommended to use coroutines or other libraries for more complex tasks.
- Services are used for tasks that should continue running even when the app is not visible, such as playing music or downloading files.
- In addition to the above, there are other types of threading mechanisms available in android such as IntentService, JobIntentService, Service, JobScheduler, and AlarmManager.
It’s important to choose the right threading mechanism for your task to ensure optimal performance and avoid threading issues. It’s also important to test your app thoroughly on different devices and configurations to ensure that it behaves correctly and does not crash due to threading issues.
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: Working with the XML Files
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" ?>
< LinearLayout
android:layout_width = "match_parent"
android:layout_height = "match_parent"
android:gravity = "center"
android:orientation = "vertical" >
< TextView
android:id = "@+id/result_text_view"
android:layout_width = "wrap_content"
android:layout_height = "wrap_content"
android:text = "Result will appear here"
android:textSize = "25sp" />
< Button
android:id = "@+id/start_button"
android:layout_width = "wrap_content"
android:layout_height = "wrap_content"
android:text = "Start" />
</ LinearLayout >
|
Step 3: Working with the MainActivity & ExampleIntentService 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.
Kotlin
import android.os.AsyncTask
import android.os.Bundle
import android.widget.Button
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
private lateinit var resultTextView: TextView
override fun onCreate(savedInstanceState: Bundle?) {
super .onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val startButton = findViewById<Button>(R.id.start_button)
resultTextView = findViewById(R.id.result_text_view)
startButton.setOnClickListener {
BackgroundTask().execute()
}
}
private inner class BackgroundTask : AsyncTask<Void?, Void?, String>() {
override fun onPostExecute(result: String) {
resultTextView.text = result
}
override fun doInBackground(vararg p0: Void?): String {
try {
Thread.sleep( 5000 )
} catch (e: InterruptedException) {
e.printStackTrace()
}
return "Task Completed"
}
}
}
|
Java
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
private TextView resultTextView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super .onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button startButton = findViewById(R.id.start_button);
resultTextView = findViewById(R.id.result_text_view);
startButton.setOnClickListener(view -> new BackgroundTask().execute());
}
private class BackgroundTask extends AsyncTask<Void, Void, String> {
@Override
protected String doInBackground(Void... voids) {
try {
Thread.sleep( 5000 );
} catch (InterruptedException e) {
e.printStackTrace();
}
return "Task Completed" ;
}
@Override
protected void onPostExecute(String result) {
resultTextView.setText(result);
}
}
}
|
Output:
Like Article
Suggest improvement
Share your thoughts in the comments
Please Login to comment...