要在Android上播放音频文件并在用户界面上保持更新，可以使用MediaPlayer类和Handler类来实现。以下是一个示例代码：

import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.SeekBar;

import androidx.appcompat.app.AppCompatActivity;

import java.io.IOException;

public class MainActivity extends AppCompatActivity {

    private MediaPlayer mediaPlayer;
    private SeekBar seekBar;
    private Button playButton;
    private boolean isPlaying = false;

    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            if (mediaPlayer != null && mediaPlayer.isPlaying()) {
                int currentPosition = mediaPlayer.getCurrentPosition();
                seekBar.setProgress(currentPosition);
                // 每100毫秒更新一次界面
                sendEmptyMessageDelayed(0, 100);
            }
        }
    };

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

        seekBar = findViewById(R.id.seekBar);
        playButton = findViewById(R.id.playButton);

        mediaPlayer = new MediaPlayer();

        try {
            mediaPlayer.setDataSource("audio_file_path"); // 替换为你的音频文件路径
            mediaPlayer.prepare();
        } catch (IOException e) {
            e.printStackTrace();
        }

        playButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (isPlaying) {
                    mediaPlayer.pause();
                    playButton.setText("播放");
                } else {
                    mediaPlayer.start();
                    playButton.setText("暂停");
                    // 开始播放后，开始更新界面
                    handler.sendEmptyMessage(0);
                }
                isPlaying = !isPlaying;
            }
        });

        seekBar.setMax(mediaPlayer.getDuration());
        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                if (fromUser) {
                    mediaPlayer.seekTo(progress);
                }
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {

            }
        });
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mediaPlayer != null) {
            mediaPlayer.release();
            mediaPlayer = null;
        }
        // 移除handler的更新消息
        handler.removeCallbacksAndMessages(null);
    }
}

上述示例代码使用MediaPlayer类播放音频文件，并使用Handler类每100毫秒更新一次SeekBar的进度条。点击播放按钮时，切换播放状态，并更新按钮的文本。拖动SeekBar时，将音频文件的播放位置设置为SeekBar的进度。在Activity销毁时，释放MediaPlayer并移除Handler的更新消息。请确保在AndroidManifest.xml文件中添加适当的权限和Activity声明。