public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);                File sdCard = Environment.getExternalStorageDirectory();    //取得sdCard 的目录                try {            //测试创建文件和文件夹            boolean CreateFileResult = createFile(sdCard.getAbsolutePath(),"sdCreateFile.sq",false); //创建文件            boolean CreateDirResult = createFile(sdCard.getAbsolutePath(),"sdCreateDir.dir",true);    //创建文件夹                    } catch (IOException e) {e.printStackTrace();}        //测试删除文件和文件夹        boolean deleteFileResult = deleteFile(sdCard.getAbsolutePath(), "sdCreateFile.sq");        boolean deleteDirResult  = deleteFile(sdCard.getAbsolutePath(), "sdCreateDir.dir");            }        //创建文件夹或目录    boolean createFile(String path,String fileName,boolean isDir) throws IOException    {        File dir = new File(path);        if(dir.exists()!=true) return false;        //path no exists        File newFile = new File(path+"/"+fileName);        return isDir==true? newFile.mkdir():newFile.createNewFile();    }        //删除文件夹或目录    boolean deleteFile(String path,String fileName)    {        File dir = new File(path);        if(dir.exists()!=true)return false;        //path no exists        return new File(path+"/"+fileName).delete();    }