public class SearchFileActivity extends Activity{
    List<String> list=new ArrayList<>();
    private ArrayAdapter<String> adapter;
    private List<String> pathlist=new ArrayList<>();

    @Override
protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.searchfile
 
);
        EditText search_edit=findViewById(R.id.search_edit);
        ListView search_list=findViewById(R.id.search_list);
        adapter = new ArrayAdapter(this, android.R.layout.simple_expandable_list_item_1, list);
        search_list.setAdapter(adapter);
        search_edit.addTextChangedListener(new 
 
TextWatcher() {
            @Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

            }

            @Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
                list.clear();

//預設為sd卡，但是此時搜尋較為卡頓，建議制定到某資料夾內部
                searchFile(charSequence.toString().trim(), "/sdcard/"
 
);
                adapter.notifyDataSetChanged();
            }

            @Override
public void afterTextChanged(Editable editable) {

            }
        });
        search_list.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
                String s = list.get(i);
                //s為選定的資料夾路徑
                
            }
        });

    }
    private void searchFile(String filename, String path) {
        File[] files = null;
        try {
            files = new File(path).listFiles();
        } catch (Exception e) {
            files = null;
            Toast.makeText(this, "搜尋", Toast.LENGTH_SHORT).show();
            return;
        }

        for (File file : files) {
            if (file.isDirectory() && file.listFiles() != null) {
                searchFile(filename, file.getPath());
            } else if (file.isFile()) {
                if (filename == null || filename.isEmpty()) {
                    list.add(file.getPath());
                } else {
                    String name = file.getName();
                    if (name.indexOf(filename) != -1) {
                        list.add(file.getPath());
                    }
                }
            }
        }
    }
}

佈局檔案

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="30dp">
<EditText
android:id="@+id/search_edit"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
    <ListView
android:id="@+id/search_list"
android:layout_width="match_parent"
android:layout_height="match_parent"></ListView>

</LinearLayout>