如何在Android上创建数字时钟？

import android.os.Bundle;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.widget.TextView;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class MainActivity extends AppCompatActivity {

    private TextView clockTextView;
    private Handler handler;

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

        clockTextView = findViewById(R.id.clockTextView);
        handler = new Handler();

        Thread clockThread = new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    handler.post(new Runnable() {
                        @Override
                        public void run() {
                            SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss", Locale.getDefault());
                            String currentTime = sdf.format(new Date());
                            clockTextView.setText(currentTime);
                        }
                    });

                    try {
                        Thread.sleep(1000); // 每秒更新一次时间
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        });

        clockThread.start();
    }
}