android 重命名文件

private void createFile() {
    File sdCard= Environment.getExternalStorageDirectory();
    String fileName = "data.txt";
    File file = new File(sdCard, fileName) ;

    if(!file.exists()){
        try {

            file.createNewFile();
            String oldPath = file.getAbsolutePath();
            String newPath =  "";
            newPath = oldPath.replace(fileName, "other.txt");
            renameFile(oldPath, newPath);
            //file is create
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    } else {
        String oldPath = file.getAbsolutePath();
        if(!TextUtils.isEmpty(oldPath)) {
            String newPath = file.getAbsolutePath() + "other.txt";
            newPath = oldPath.replace(fileName, "other.txt");
            renameFile(oldPath, newPath);
        }

    }
}

/**
 * oldPath 和 newPath必须是新旧文件的绝对路径
 * */
private void renameFile(String oldPath, String newPath) {
    if(TextUtils.isEmpty(oldPath)) {
        return;
    }

    if(TextUtils.isEmpty(newPath)) {
        return;
    }

    File file = new File(oldPath);
    file.renameTo(new File(newPath));
}