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ファイルの変換:AndroidでのUriからファイルへ

Androidでfile:Android.net.UriからFileに変換する最も簡単な方法は何ですか?

以下を試してみましたが、うまくいきません。

 final File file = new File(Environment.getExternalStorageDirectory(), "read.me");
 Uri uri = Uri.fromFile(file);
 File auxFile = new File(uri.toString());
 assertEquals(file.getAbsolutePath(), auxFile.getAbsolutePath());
339
hpique

あなたが欲しいのは….

new File(uri.getPath());

...そして….

new File(uri.toString());

注:uri.toString()はStringを"file:///mnt/sdcard/myPicture.jpg"の形式で返し、uri.getPath()はStringを"/mnt/sdcard/myPicture.jpg"の形式で返します。

690
Adil Hussain

長い間検索した後、これは私のために働いたものです:

File file = new File(getPath(uri));


public String getPath(Uri uri) 
    {
        String[] projection = { MediaStore.Images.Media.DATA };
        Cursor cursor = getContentResolver().query(uri, projection, null, null, null);
        if (cursor == null) return null;
        int column_index =             cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
        cursor.moveToFirst();
        String s=cursor.getString(column_index);
        cursor.close();
        return s;
    }
37
Sanket Berde

編集:申し訳ありませんが、私は前にテストした方が良いです。これはうまくいくはずです。

new File(new URI(androidURI.toString()));

URIはJava.net.URIです。

26

つかいます

InputStream inputStream = getContentResolver().openInputStream(uri);    

直接ファイルをコピーしてください。また見なさい:

https://developer.Android.com/guide/topics/providers/document-provider.html

これのどれも私のために働きません。これが実用的な解決策であることがわかりました。 しかし私の場合は画像に限定されます

String[] filePathColumn = { MediaStore.Images.Media.DATA };
Cursor cursor = getActivity().getContentResolver().query(uri, filePathColumn, null, null, null);
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
String filePath = cursor.getString(columnIndex);
cursor.close();
11
Jacek Kwiecień

最善の解決策

シンプルなFileUtil Javaクラスを1つ作成し、ファイルの作成、コピー、名前変更に使用します

私はuri.toString()uri.getPath()を使っていますが、うまくいきません。私はついにこの解決策を見つけました。

import Android.content.Context;
import Android.database.Cursor;
import Android.net.Uri;
import Android.provider.OpenableColumns;
import Android.util.Log;

import Java.io.File;
import Java.io.FileNotFoundException;
import Java.io.FileOutputStream;
import Java.io.IOException;
import Java.io.InputStream;
import Java.io.OutputStream;

public class FileUtil {
    private static final int EOF = -1;
    private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;

    private FileUtil() {

    }

    public static File from(Context context, Uri uri) throws IOException {
        InputStream inputStream = context.getContentResolver().openInputStream(uri);
        String fileName = getFileName(context, uri);
        String[] splitName = splitFileName(fileName);
        File tempFile = File.createTempFile(splitName[0], splitName[1]);
        tempFile = rename(tempFile, fileName);
        tempFile.deleteOnExit();
        FileOutputStream out = null;
        try {
            out = new FileOutputStream(tempFile);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        if (inputStream != null) {
            copy(inputStream, out);
            inputStream.close();
        }

        if (out != null) {
            out.close();
        }
        return tempFile;
    }

    private static String[] splitFileName(String fileName) {
        String name = fileName;
        String extension = "";
        int i = fileName.lastIndexOf(".");
        if (i != -1) {
            name = fileName.substring(0, i);
            extension = fileName.substring(i);
        }

        return new String[]{name, extension};
    }

    private static String getFileName(Context context, Uri uri) {
        String result = null;
        if (uri.getScheme().equals("content")) {
            Cursor cursor = context.getContentResolver().query(uri, null, null, null, null);
            try {
                if (cursor != null && cursor.moveToFirst()) {
                    result = cursor.getString(cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME));
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (cursor != null) {
                    cursor.close();
                }
            }
        }
        if (result == null) {
            result = uri.getPath();
            int cut = result.lastIndexOf(File.separator);
            if (cut != -1) {
                result = result.substring(cut + 1);
            }
        }
        return result;
    }

    private static File rename(File file, String newName) {
        File newFile = new File(file.getParent(), newName);
        if (!newFile.equals(file)) {
            if (newFile.exists() && newFile.delete()) {
                Log.d("FileUtil", "Delete old " + newName + " file");
            }
            if (file.renameTo(newFile)) {
                Log.d("FileUtil", "Rename file to " + newName);
            }
        }
        return newFile;
    }

    private static long copy(InputStream input, OutputStream output) throws IOException {
        long count = 0;
        int n;
        byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
        while (EOF != (n = input.read(buffer))) {
            output.write(buffer, 0, n);
            count += n;
        }
        return count;
    }
}

あなたのコードでFileUtilクラスを使う

try {
         File file = FileUtil.from(MainActivity.this,fileUri);
         Log.d("file", "File...:::: uti - "+file .getPath()+" file -" + file + " : " + file .exists());

  } catch (IOException e) {
          e.printStackTrace();
  }
8
vishwa

Kotlinを使えばさらに簡単です。

val file = File(uri.path)

または、Android用の Kotlin拡張機能を使用している場合

val file = uri.toFile()

Android + Kotlin

  1. Kotlin Android拡張機能への依存関係を追加します。

    implementation 'androidx.core:core-ktx:{latestVersion}'

  2. URIからファイルを取得します。

    uri.toFile()

Android + Java

トップに移動するだけです。

4
Hemant Kaushik

私はこれを次のようにしました。

try {
    readImageInformation(new File(contentUri.getPath()));

} catch (IOException e) {
    readImageInformation(new File(getRealPathFromURI(context,
                contentUri)));
}

public static String getRealPathFromURI(Context context, Uri contentUri) {
        String[] proj = { MediaStore.Images.Media.DATA };
        Cursor cursor = context.getContentResolver().query(contentUri, proj,
                null, null, null);
        int column_index = cursor
                .getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
        cursor.moveToFirst();
        return cursor.getString(column_index);
}

だから基本的に私はファイル、すなわちカメラで撮ってSDカードに保存した写真を使うことを試みる。これは、以下によって返される画像には機能しません。Intent photoPickerIntent = new Intent(Intent.ACTION_PICK);その場合、getRealPathFromURI()関数によってUriを実際のパスに変換する必要があります。だから結論はそれはあなたがFileに変換したいUriの種類に依存するということです。

1
Kovács Ede

@ CommonsWareはすべてのことを非常によく説明しました。そして、私たちは本当に彼が提案した解決策を使うべきです。

ちなみに、ContentResolverを問い合わせるときに頼ることができる情報だけが、ここで述べられているようにファイルの名前とサイズです: Android開発者

ご覧のとおり、DISPLAY_NAMEとSIZEの2つのフィールドのみを含むインターフェースOpenableColumnsがあります。

私の場合は、JPEG画像に関するEXIF情報を取得し、必要に応じて回転させてサーバーに送信する必要がありました。そのためには、ContentResolveropenInputStream()を使ってファイルの内容を一時ファイルにコピーしました。

1
Bogdan Kornev

この場合、特にAndroidでは、バイト数を増やす方が通常は速いです。

これにより、ストリームを介してファイルへのバイトの読み書きを処理する責任を持つクラスFileHelperと、Uriのパスとパーミッションを把握する責任を持つクラスUriHelperを設定して解決しました。

それが一般的にわかっている限りでは、string.getBytes((charset == null) ? DEFAULT_CHARSET:charset)は私達があなたが必要とするバイトにあなたが欲しい文字列を転送するのを助けることができます。

UriHelperとFileHelperに、あなたがUriによって記録された写真をファイルにコピーさせるには、以下のように実行します。

FileHelper.getInstance().copy(UriHelper.getInstance().toFile(uri_of_a_picture)
                        , FileHelper.getInstance().createExternalFile(null, UriHelper.getInstance().generateFileNameBasedOnTimeStamp()
                                + UriHelper.getInstance().getFileName(uri_of_a_picture, context), context)
                );

私のUriHelperについて:

public class UriHelper {
private static UriHelper INSTANCE = new UriHelper();

public static UriHelper getInstance() {
    return INSTANCE;
}

@SuppressLint("SimpleDateFormat")
public String generateFileNameBasedOnTimeStamp() {
    return new SimpleDateFormat("yyyyMMdd_hhmmss").format(new Date()) + ".jpeg";
}

/**
 * if uri.getScheme.equals("content"), open it with a content resolver.
 * if the uri.Scheme.equals("file"), open it using normal file methods.
 */
//

public File toFile(Uri uri) {
    if (uri == null) return null;
    Logger.d(">>> uri path:" + uri.getPath());
    Logger.d(">>> uri string:" + uri.toString());
    return new File(uri.getPath());
}

public DocumentFile toDocumentFile(Uri uri) {
    if (uri == null) return null;
    Logger.d(">>> uri path:" + uri.getPath());
    Logger.d(">>> uri string:" + uri.toString());
    return DocumentFile.fromFile(new File(uri.getPath()));
}

public Uri toUri(File file) {
    if (file == null) return null;
    Logger.d(">>> file path:" + file.getAbsolutePath());
    return Uri.fromFile(file); //returns an immutable URI reference representing the file
}

public String getPath(Uri uri, Context context) {
    if (uri == null) return null;
    if (uri.getScheme() == null) return null;
    Logger.d(">>> uri path:" + uri.getPath());
    Logger.d(">>> uri string:" + uri.toString());
    String path;
    if (uri.getScheme().equals("content")) {
        //Cursor cursor = context.getContentResolver().query(uri, new String[] {MediaStore.Images.ImageColumns.DATA}, null, null, null);
        Cursor cursor = context.getContentResolver().query(uri, null, null, null, null);
        if (cursor == null) {
            Logger.e("!!! cursor is null");
            return null;
        }
        if (cursor.getCount() >= 0) {
            Logger.d("... the numbers of rows:" + cursor.getCount()
                        + "and the numbers of columns:" + cursor.getColumnCount());
            if (cursor.isBeforeFirst()) {
                while (cursor.moveToNext()) {
                    StringBuilder stringBuilder = new StringBuilder();
                    for (int i = 0; i<cursor.getColumnCount(); i++) {
                        stringBuilder.append("... iterating cursor.getString(" + i +"(" + cursor.getColumnName(i) + ")):" + cursor.getString(i));
                        stringBuilder.append("\n");
                    }
                    Logger.d(stringBuilder.toString());
                }
            } else {
                cursor.moveToFirst();
                do {
                    StringBuilder stringBuilder = new StringBuilder();
                    for (int i = 0; i<cursor.getColumnCount(); i++) {
                        stringBuilder.append("... iterating cursor.getString(" + i +"(" + cursor.getColumnName(i) + ")):" + cursor.getString(i));
                        stringBuilder.append("\n");
                    }
                    Logger.d(stringBuilder.toString());
                } while (cursor.moveToNext());
            }
            path = uri.getPath();
            cursor.close();
            Logger.d("... content scheme:" + uri.getScheme() + "  and return:" + path);
            return path;
        } else {
            path = uri.getPath();
            Logger.d("... content scheme:" + uri.getScheme()
                    + " but the numbers of rows in the cursor is < 0:" + cursor.getCount()
                    + "  and return:" + path);
            return path;
        }
    } else {
        path = uri.getPath();
        Logger.d("... not content scheme:" + uri.getScheme() + "  and return:" + path);
        return path;
    }
}

public String getFileName(Uri uri, Context context) {
    if (uri == null) return null;
    if (uri.getScheme() == null) return null;
    Logger.d(">>> uri path:" + uri.getPath());
    Logger.d(">>> uri string:" + uri.toString());
    String path;
    if (uri.getScheme().equals("content")) {
        //Cursor cursor = context.getContentResolver().query(uri, new String[] {MediaStore.Images.ImageColumns.DATA}, null, null, null);
        Cursor cursor = context.getContentResolver().query(uri, null, null, null, null);
        if (cursor == null) {
            Logger.e("!!! cursor is null");
            return null;
        }
        if (cursor.getCount() >= 0) {
            Logger.d("... the numbers of rows:" + cursor.getCount()
                    + "and the numbers of columns:" + cursor.getColumnCount());
            if (cursor.isBeforeFirst()) {
                while (cursor.moveToNext()) {
                    StringBuilder stringBuilder = new StringBuilder();
                    for (int i = 0; i<cursor.getColumnCount(); i++) {
                        stringBuilder.append("... iterating cursor.getString(" + i +"(" + cursor.getColumnName(i) + ")):" + cursor.getString(i));
                        stringBuilder.append("\n");
                    }
                    Logger.d(stringBuilder.toString());
                }
            } else {
                cursor.moveToFirst();
                do {
                    StringBuilder stringBuilder = new StringBuilder();
                    for (int i = 0; i<cursor.getColumnCount(); i++) {
                        stringBuilder.append("... iterating cursor.getString(" + i +"(" + cursor.getColumnName(i) + ")):" + cursor.getString(i));
                        stringBuilder.append("\n");
                    }
                    Logger.d(stringBuilder.toString());
                } while (cursor.moveToNext());
            }
            cursor.moveToFirst();
            path = cursor.getString(cursor.getColumnIndex(MediaStore.Images.ImageColumns.DISPLAY_NAME));
            cursor.close();
            Logger.d("... content scheme:" + uri.getScheme() + "  and return:" + path);
            return path;
        } else {
            path = uri.getLastPathSegment();
            Logger.d("... content scheme:" + uri.getScheme()
                    + " but the numbers of rows in the cursor is < 0:" + cursor.getCount()
                    + "  and return:" + path);
            return path;
        }
    } else {
        path = uri.getLastPathSegment();
        Logger.d("... not content scheme:" + uri.getScheme() + "  and return:" + path);
        return path;
    }
}

}

私のFileHelperについて:

public class FileHelper {
private static final String DEFAULT_DIR_NAME = "AmoFromTaiwan";
private static final int DEFAULT_BUFFER_SIZE = 1024;
private static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
private static final int EOF = -1;
private static FileHelper INSTANCE = new FileHelper();

public static FileHelper getInstance() {
    return INSTANCE;
}

private boolean isExternalStorageWritable(Context context) {
    /*
    String state = Environment.getExternalStorageState();
    return Environment.MEDIA_MOUNTED.equals(state);
    */
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if (context.checkSelfPermission(Android.Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
            return true;
        } else {
            Logger.e("!!! checkSelfPermission() not granted");
            return false;
        }
    } else { //permission is automatically granted on sdk<23 upon installation
        return true;
    }
}

private boolean isExternalStorageReadable(Context context) {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if (context.checkSelfPermission(Android.Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
            return true;
        } else {
            Logger.e("!!! checkSelfPermission() not granted");
            return false;
        }
    } else { //permission is automatically granted on sdk<23 upon installation
        return true;
    }
}

@SuppressLint("SimpleDateFormat")
private String generateFileNameBasedOnTimeStamp() {
    return new SimpleDateFormat("yyyyMMdd_hhmmss").format(new Date()) + ".jpeg";
}

public File createExternalFile(String dir_name, String file_name, Context context) {
    String dir_path;
    String file_path;
    File dir ;
    File file;
    if (!isExternalStorageWritable(context)) {
        Logger.e("!!! external storage not writable");
        return null;
    }
    if (dir_name == null) {
        dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
    } else {
        dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
    }
    Logger.d("... going to access an external dir:" + dir_path);
    dir = new File(dir_path);
    if (!dir.exists()) {
        Logger.d("... going to mkdirs:" + dir_path);
        if (!dir.mkdirs()) {
            Logger.e("!!! failed to mkdirs");
            return null;
        }
    }
    if (file_name == null) {
        file_path = dir_path + File.separator + generateFileNameBasedOnTimeStamp();
    } else {
        file_path = dir_path + File.separator + file_name;
    }
    Logger.d("... going to return an external dir:" + file_path);
    file = new File(file_path);
    if (file.exists()) {
        Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
        if (!file.delete()) {
            Logger.e("!!! failed to delete file");
            return null;
        }
    }
    return file;
}

public File createInternalFile(String dir_name, String file_name, Context context) {
    String dir_path;
    String file_path;
    File dir ;
    File file;
    if (dir_name == null) {
        dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
    } else {
        dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
    }
    dir_path = dir.getAbsolutePath();
    Logger.d("... going to access an internal dir:" + dir_path);
    if (!dir.exists()) {
        Logger.d("... going to mkdirs:" + dir_path);
        if (!dir.mkdirs()) {
            Logger.e("!!! mkdirs failed");
            return null;
        }
    }
    if (file_name == null) {
        file = new File(dir, generateFileNameBasedOnTimeStamp());
    } else {
        file = new File(dir, file_name);
    }
    file_path = file.getAbsolutePath();
    Logger.d("... going to return an internal dir:" + file_path);
    if (file.exists()) {
        Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
        if (!file.delete()) {
            Logger.e("!!! failed to delete file");
            return null;
        }
    }
    return file;
}

public File getExternalFile(String dir_name, String file_name, Context context) {
    String dir_path;
    String file_path;
    File file;
    if (!isExternalStorageWritable(context)) {
        Logger.e("!!! external storage not writable");
        return null;
    }
    if (dir_name == null) {
        dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
    } else {
        dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
    }
    if (file_name == null) {
        file_path = dir_path;
    } else {
        file_path = dir_path + File.separator + file_name;
    }
    Logger.d("... going to return an external file:" + file_path);
    file = new File(file_path);
    if (file.exists()) {
        Logger.d("... file exists:" + file.getAbsolutePath());
    } else {
        Logger.e("!!! file does't exist:" + file.getAbsolutePath());
    }
    return file;
}

public File getInternalFile(String dir_name, String file_name, Context context) {
    String file_path;
    File dir ;
    File file;
    if (dir_name == null) {
        dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
    } else {
        dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
    }
    if (file_name == null) {
        file = new File(dir.getAbsolutePath());
    } else {
        file = new File(dir, file_name);
    }
    file_path = file.getAbsolutePath();
    Logger.d("... going to return an internal dir:" + file_path);
    if (file.exists()) {
        Logger.d("... file exists:" + file.getAbsolutePath());
    } else {
        Logger.e("!!! file does't exist:" + file.getAbsolutePath());
    }
    return file;
}

private byte[] readBytesFromFile(File file) {
    Logger.d(">>> path:" + file.getAbsolutePath());
    FileInputStream fis;
    long file_length;
    byte[] buffer;
    int offset = 0;
    int next = 0;
    if (!file.exists()) {
        Logger.e("!!! file doesn't exists");
        return null;
    }
    if (file.length() > Integer.MAX_VALUE) {
        Logger.e("!!! file length is out of max of int");
        return null;
    } else {
        file_length = file.length();
    }
    try {
        fis = new FileInputStream(file);
        //buffer = new byte[(int) file_length];
        buffer = new byte[(int) file.length()];
        long time_start = System.currentTimeMillis();
        while (true) {
            Logger.d("... now next:" + next + " and offset:" + offset);
            if (System.currentTimeMillis() - time_start > 1000) {
                Logger.e("!!! left due to time out");
                break;
            }
            next = fis.read(buffer, offset, (buffer.length-offset));
            if (next < 0 || offset >= buffer.length) {
                Logger.d("... completed to read");
                break;
            }
            offset += next;
        }
        //if (offset < buffer.length) {
        if (offset < (int) file_length) {
            Logger.e("!!! not complete to read");
            return null;
        }
        fis.close();
        return buffer;
    } catch (IOException e) {
        e.printStackTrace();
        Logger.e("!!! IOException");
        return null;
    }
}

public byte[] readBytesFromFile(File file, boolean is_fis_fos_only) {
    if (file == null) return null;
    if (is_fis_fos_only) {
        return readBytesFromFile(file);
    }
    Logger.d(">>> path:" + file.getAbsolutePath());
    FileInputStream fis;
    BufferedInputStream bis;
    ByteArrayOutputStream bos;
    byte[] buf = new byte[(int) file.length()];
    int num_read;
    if (!file.exists()) {
        Logger.e("!!! file doesn't exists");
        return null;
    }
    try {
        fis = new FileInputStream(file);
        bis = new BufferedInputStream(fis);
        bos = new ByteArrayOutputStream();
        long time_start = System.currentTimeMillis();
        while (true) {
            if (System.currentTimeMillis() - time_start > 1000) {
                Logger.e("!!! left due to time out");
                break;
            }
            num_read = bis.read(buf, 0, buf.length); //1024 bytes per call
            if (num_read < 0) break;
            bos.write(buf, 0, num_read);
        }
        buf = bos.toByteArray();
        fis.close();
        bis.close();
        bos.close();
        return buf;
    } catch (FileNotFoundException e) {
        e.printStackTrace();
        Logger.e("!!! FileNotFoundException");
        return null;
    } catch (IOException e) {
        e.printStackTrace();
        Logger.e("!!! IOException");
        return null;
    }
}

/**
 * streams (InputStream and OutputStream) transfer binary data
 * if to write a string to a stream, must first convert it to bytes, or in other words encode it
 */
public boolean writeStringToFile(File file, String string, Charset charset) {
    if (file == null) return false;
    if (string == null) return false;
    return writeBytesToFile(file, string.getBytes((charset == null) ? DEFAULT_CHARSET:charset));
}

public boolean writeBytesToFile(File file, byte[] data) {
    if (file == null) return false;
    if (data == null) return false;
    FileOutputStream fos;
    BufferedOutputStream bos;
    try {
        fos = new FileOutputStream(file);
        bos = new BufferedOutputStream(fos);
        bos.write(data, 0, data.length);
        bos.flush();
        bos.close();
        fos.close();
    } catch (IOException e) {
        e.printStackTrace();
        Logger.e("!!! IOException");
        return false;
    }
    return true;
}

/**
 * io blocks until some input/output is available.
 */
public boolean copy(File source, File destination) {
    if (source == null || destination == null) return false;
    Logger.d(">>> source:" + source.getAbsolutePath() + ", destination:" + destination.getAbsolutePath());
    try {
        FileInputStream fis = new FileInputStream(source);
        FileOutputStream fos = new FileOutputStream(destination);
        byte[] buffer = new byte[(int) source.length()];
        int len;
        while (EOF != (len = fis.read(buffer))) {
            fos.write(buffer, 0, len);
        }
        if (true) { //debug
            byte[] copies = readBytesFromFile(destination);
            if (copies != null) {
                int copy_len = copies.length;
                Logger.d("... stream read and write done for " + copy_len + " bytes");
            }
        }
        return destination.length() != 0;
    } catch (IOException e) {
        e.printStackTrace();
        return false;
    }
}

public void list(final String path, final String end, final List<File> files) {
    Logger.d(">>> path:" + path + ", end:" + end);
    File file = new File(path);
    if (file.isDirectory()) {
        for (File child : file.listFiles()){
            list(child.getAbsolutePath(), end, files);
        }
    } else if (file.isFile()) {
        if (end.equals("")) {
            files.add(file);
        } else {
            if (file.getName().endsWith(end)) files.add(file);
        }
    }
}

public String[] splitFileName(File file, String split) {
    String path;
    String ext;
    int lastIndexOfSplit = file.getAbsolutePath().lastIndexOf(split);
    if (lastIndexOfSplit < 0) {
        path = file.getAbsolutePath();
        ext = "";
    } else {
        path = file.getAbsolutePath().substring(0, lastIndexOfSplit);
        ext = file.getAbsolutePath().substring(lastIndexOfSplit);
    }
    return new String[] {path, ext};
}

public File rename(File old_file, String new_name) {
    if (old_file == null || new_name == null) return null;
    Logger.d(">>> old file path:" + old_file.getAbsolutePath() + ", new file name:" + new_name);
    File new_file = new File(old_file, new_name);
    if (!old_file.equals(new_file)) {
        if (new_file.exists()) { //if find out previous file/dir at new path name exists
            if (new_file.delete()) {
                Logger.d("... succeeded to delete previous file at new abstract path name:" + new_file.getAbsolutePath());
            } else {
                Logger.e("!!! failed to delete previous file at new abstract path name");
                return null;
            }
        }
        if (old_file.renameTo(new_file)) {
            Logger.d("... succeeded to rename old file to new abstract path name:" + new_file.getAbsolutePath());
        } else {
            Logger.e("!!! failed to rename old file to new abstract path name");
        }
    } else {
        Logger.d("... new and old file have the equal abstract path name:" + new_file.getAbsolutePath());
    }
    return new_file;
}

public boolean remove(final String path, final String end) {
    Logger.d(">>> path:" + path + ", end:" + end);
    File file = new File(path);
    boolean result = false;
    if (file.isDirectory()) {
        for (File child : file.listFiles()){
            result = remove(child.getAbsolutePath(), end);
        }
    } else if (file.isFile()) {
        if (end.equals("")) {
            result = file.delete();
        } else {
            if (file.getName().endsWith(end)) result = file.delete();
        }
    } else {
        Logger.e("!!! child is not file or directory");
    }
    return result;
}

@TargetApi(Build.VERSION_CODES.O)
public byte[] readNIOBytesFromFile(String path) throws IOException {
    Logger.d(">>> path:" + path);
    if (!Files.exists(Paths.get(path), LinkOption.NOFOLLOW_LINKS)) {
        Logger.e("!!! file doesn't exists");
        return null;
    } else {
        return Files.readAllBytes(Paths.get(path));
    }
}

@TargetApi(Build.VERSION_CODES.O)
public File writeNIOBytesToFile(String dir, String name, byte[] data) {
    Logger.d(">>> dir:" + dir + ", name:" + name);
    Path path_dir;
    Path path_file;
    try {
        if (!Files.exists(Paths.get(dir), LinkOption.NOFOLLOW_LINKS)) {
            Logger.d("... make a dir");
            path_dir = Files.createDirectories(Paths.get(dir));
            if (path_dir == null) {
                Logger.e("!!! failed to make a dir");
                return null;
            }
        }
        path_file = Files.write(Paths.get(name), data);
        return path_file.toFile();
    } catch (IOException e) {
        e.printStackTrace();
        Logger.e("!!! IOException");
        return null;
    }
}

@TargetApi(Build.VERSION_CODES.O)
public void listNIO(final String dir, final String end, final List<File> files) throws IOException {
    Logger.d(">>> dir:" + dir + ", end:" + end);
    Files.walkFileTree(Paths.get(dir), new FileVisitor<Path>() {
        @Override
        public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
            Logger.d("... file:" + dir.getFileName());
            return FileVisitResult.CONTINUE;
        }

        @Override
        public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
            Logger.d("... file:" + file.getFileName());
            if (end.equals("")) {
                files.add(file.toFile());
            } else {
                if (file.endsWith(end)) files.add(file.toFile());
            }
            return FileVisitResult.CONTINUE;
        }

        @Override
        public FileVisitResult visitFileFailed(Path file, IOException exc) {
            Logger.d("... file:" + file.getFileName());
            if (end.equals("")) {
                files.add(file.toFile());
            } else {
                if (file.endsWith(end)) files.add(file.toFile());
            }
            return FileVisitResult.CONTINUE;
        }

        @Override
        public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
            Logger.d("... file:" + dir.getFileName());
            return FileVisitResult.CONTINUE;
        }
    });
}

/**
 * recursion
 */
private int factorial (int x) {
    if (x > 1) return (x*(factorial(x-1)));
    else if (x == 1) return x;
    else return 0;
}

}

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