Android Handler

MainActivity.java

package com.e.handler;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {


    private static final String TAG = "MainActivity";

    Button btnStar;
    ProgressBar progressBar;
    TextView txtCount;

    int MAX_COUNT = 100;
    Handler mHandlerThread;
    private static final int START_PROGRESS = 100;
    private static final int UPDATE_COUNT = 101;

    Thread thread;

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


        btnStar = findViewById(R.id.btnStart);
        progressBar = findViewById(R.id.progressBar);
        txtCount = findViewById(R.id.txtCount);
        progressBar.setMax(MAX_COUNT);

        btnStar.setOnClickListener(this);

        thread = new Thread(new Runnable() {
            @Override
            public void run() {
                for (int count = 0; count <= 100; count++) {
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException ex) {
                        ex.printStackTrace();
                    }
                    Message message = new Message();
                    message.what = UPDATE_COUNT;
                    message.arg1 = count;
                    mHandlerThread.sendMessage(message);
                }
            }
        });


    }

    @Override
    public void onClick(View view) {
        if (view.getId() == R.id.btnStart) {
            mHandlerThread.sendEmptyMessage(START_PROGRESS);
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        mHandlerThread = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                if (msg.what == START_PROGRESS) {
                    thread.start();
                } else if (msg.what == UPDATE_COUNT) {
                    txtCount.setText("Progress Count : " + msg.arg1);
                    progressBar.setProgress(msg.arg1);
                }
            }
        };
    }
}