How to stop AsyncTask thread in android?

This example demonstrates how do I stop AsynchTask thread in android.

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
   xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity">
   <Button
      android:id="@+id/btnDo"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_above="@id/btnCancel"
      android:layout_centerInParent="true"
      android:layout_marginBottom="25sp"
      android:text="Do AsyncTask" />
   <Button
      android:id="@+id/btnCancel"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_above="@id/textView"
      android:layout_centerInParent="true"
      android:layout_marginBottom="20dp"
      android:text="Cancel" />
   <TextView
      android:id="@+id/textView"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:textSize="20sp"
      android:gravity="center_horizontal" />
</RelativeLayout>

Step 3 − Add the following code to src/MainActivity.java

import android.graphics.Color;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
   private Button btnDo, btnCancel;
   private TextView textView;
   private AsyncTask myTask;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      btnDo = findViewById(R.id.btnDo);
      btnCancel = findViewById(R.id.btnCancel);
      textView = findViewById(R.id.textView);
      btnDo.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            textView.setText("");
            myTask = new DownloadTask().execute("Task1",
               "Task2", "Task3", "Task4", "Task5");
         }
      });
      btnCancel.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            myTask.cancel(true);
         }
      });
   }
   private class DownloadTask extends AsyncTask<String, Integer, List<String>> {
      @Override
      protected void onPreExecute() {
         super.onPreExecute();
         textView.setTextColor(Color.BLUE);
         textView.setText(textView.getText() + "
 Starting Task....");
      }
      @Override
      protected List<String> doInBackground(String... tasks) {
         int count = tasks.length;
         List<String> taskList= new ArrayList<>(count);
         for(int i =0;i<count;i++){
            String currentTask = tasks[i];
            taskList.add(currentTask);
            try {
               Thread.sleep(1000);
            } catch (InterruptedException e) {
               e.printStackTrace();
            }
            publishProgress((int) (((i+1) / (float) count) * 100));
            if(isCancelled()){
               break;
            }
         }
         return taskList;
      }
      @Override
      protected void onCancelled() {
         super.onCancelled();
         textView.setTextColor(Color.RED);
         textView.setText(textView.getText() + "
 Operation is cancelled..");
      }
      @Override
      protected void onProgressUpdate(Integer... progress) {
         super.onProgressUpdate(progress);
         textView.setText(textView.getText()+ "
 Completed:)" + progress[0] + "%");
      }
      @Override
      protected void onPostExecute(List<String> result) {
         super.onPostExecute(result);
         textView.setText(textView.getText() + "

 Done....");
         for (int i=0;i<result.size();i++){
            textView.setText(textView.getText() + "
" +
            result.get(i));
         }
      }
   }
}

Step 4 − Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest
   xmlns:android="http://schemas.android.com/apk/res/android"
   package="app.com.sample">
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action
               android:name="android.intent.action.MAIN" />
            <category
               android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen −