Cảm ơn bác nhiều ạ ^^

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;

class MP3Filter implements FilenameFilter{

    @Override
    public boolean accept(File dir, String name) {
        return (name.endsWith(".mp3"));
    }
}

public class MainActivity extends AppCompatActivity {

    ListView lvDanhsach;
    static ArrayList<String> dsBaihat;
    ArrayAdapter<String> adapter;

    private static final String Path = "/sdcard/Music";

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

        lvDanhsach = (ListView) findViewById(R.id.lvDanhsach);
        dsBaihat = new ArrayList<>();
        adapter = new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,dsBaihat);
        lvDanhsach.setAdapter(adapter);

        updateListSong();

        lvDanhsach.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Intent intent = new Intent(MainActivity.this,PlayMusicActivity.class);
                File pathMusic = new File(Path + "/" + dsBaihat.get(position));
                intent.putExtra("FILE", pathMusic.getPath());
                //Toast.makeText(getApplicationContext(),String.valueOf(pathMusic.getUsableSpace()),Toast.LENGTH_SHORT).show();
                startActivity(intent);
            }
        });

    }

    private void updateListSong(){
        File file = new File(Path);
        if(file.listFiles(new MP3Filter()).length > 0){
            for (File f : file.listFiles(new MP3Filter())) {
                dsBaihat.add(f.getName().toString());
                //Toast.makeText(getApplicationContext(),f.getName().toString(),Toast.LENGTH_LONG).show();
            }
        }
    }