Apps Can't create handler inside thread that has not called Looper.prepare()

08-01 19:19:43.254 5291-5291/com.example.app1 E/APP: RUNNING
08-01 19:19:43.254 5291-5291/com.example.app1 E/APP: onChanged
08-01 19:19:43.259 5291-5320/com.example.app1 E/WM-WorkerWrapper: Work [ id=495d1e86-0f1f-42a5-9997-3a3c01b878d3, tags={ *****, com.example.app1.UploadWorker } ] failed because it threw an exception/error
    java.util.concurrent.ExecutionException: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
        at androidx.work.impl.utils.futures.AbstractFuture.getDoneValue(AbstractFuture.java:516)
        at androidx.work.impl.utils.futures.AbstractFuture.get(AbstractFuture.java:475)
        at androidx.work.impl.WorkerWrapper$2.run(WorkerWrapper.java:284)
        at androidx.work.impl.utils.SerialExecutor$Task.run(SerialExecutor.java:75)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
        at java.lang.Thread.run(Thread.java:856)
     Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
        at android.os.Handler.<init>(Handler.java:121)
        at android.app.Activity.<init>(Activity.java:749)
        at androidx.core.app.ComponentActivity.<init>(ComponentActivity.java:39)
        at androidx.activity.ComponentActivity.<init>(ComponentActivity.java:84)
        at androidx.fragment.app.FragmentActivity.<init>(FragmentActivity.java:127)
        at androidx.appcompat.app.AppCompatActivity.<init>(AppCompatActivity.java:77)
        at com.example.app1.MainActivity.<init>(MainActivity.java:19)
        at com.example.app1.UploadWorker.doWork(UploadWorker.java:20)
        at androidx.work.Worker$1.run(Worker.java:85)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076) 
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569) 
        at java.lang.Thread.run(Thread.java:856)

package com.example.app1;

import android.content.Context;
import android.util.Log;

import androidx.annotation.NonNull;
import androidx.work.Data;
import androidx.work.Worker;
import androidx.work.WorkerParameters;

public class UploadWorker extends Worker {

    public UploadWorker(@NonNull Context context, @NonNull WorkerParameters workerParams) {
        super(context, workerParams);
    }

    @NonNull
    @Override
    public Result doWork() {
        String key = new MainActivity().KEY_NAME;
        Data ret = new Data.Builder().putLong(key, System.currentTimeMillis()).build();
        Log.e("APP", "doWork");
        return Result.success(ret);
    }
}

package com.example.app1;

import androidx.appcompat.app.AppCompatActivity;
import androidx.lifecycle.LiveData;
import androidx.lifecycle.Observer;
import androidx.work.BackoffPolicy;
import androidx.work.Constraints;
import androidx.work.Data;
import androidx.work.OneTimeWorkRequest;
import androidx.work.WorkInfo;
import androidx.work.WorkManager;

import android.os.Bundle;
import android.util.Log;

import java.util.List;
import java.util.concurrent.TimeUnit;

public class MainActivity extends AppCompatActivity {

    public final String KEY_NAME = "string1";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Log.e("START", "Start");

        Constraints constraints = new Constraints.Builder().setRequiresCharging(true).build();
        Data data = new Data.Builder().putString(KEY_NAME, "Mike").build();
        OneTimeWorkRequest uploadWordRequest = new OneTimeWorkRequest.Builder(UploadWorker.class)
                .setConstraints(constraints)
                .setInitialDelay(10, TimeUnit.SECONDS)
                .setBackoffCriteria(BackoffPolicy.EXPONENTIAL, 5, TimeUnit.SECONDS)
                .setInputData(data)
                .addTag("tag")
                .build();
        WorkManager w = WorkManager.getInstance(getApplicationContext());
        w.enqueue(uploadWordRequest);
        LiveData<List<WorkInfo>> l = w.getWorkInfosByTagLiveData("tag");
        l.observe(this, new Observer<List<WorkInfo>>() {
            @Override
            public void onChanged(List<WorkInfo> workInfos) {
                if(workInfos.get(0).getState() == WorkInfo.State.RUNNING)
                    Log.e("APP", "RUNNING");
                Log.e("APP", "onChanged");
            }
        });
    }
}