(1)建立資料夾

File myDir = new File("目錄地址");

if (!myDir.exists()) {

      myDir.mkdir();

}

(2)刪除資料夾

File myDir = new File("");

① 刪除空資料夾

myDir.delete();

② 刪除資料夾下的所有檔案

File[] files = myDir.listFiles();

for (int i = 0 ; i < files.length ; i++){

      if (files[i].isDirectory()){

           files[i].delete();

      }

}

(3)清空資料夾

File myDir = new File("");

(4)建立檔案

File myFile = new File("檔案地址");

if (!myFile.exists()) {

     myFile.createNewFile();

}

FileWriter resultFile = newFileWriter(myFile);

PrintWriter myFileWriter = newPrintWriter(resultFile);

myFileWriter.println(str2);

resultFile.close();

將物件寫入檔案：

FileOutputStream outstream =newFileOutputStream("library.dat");

ObjectOutputStream out =newObjectOutputStream(outstream);

out.writeObject(me); 

out.close();

從檔案中讀取物件：

ObjectInputStream in =newObjectInputStream(new FileInputStream("library.dat"));

Person who = (Person)in.readObject();

(5)刪除檔案

File myFile = new File("");

myFile.delete();

(6)讀取檔案

FileReader fr = newFileReader("");

BufferedReaderReader(fr);

String str = br.readLine();

while (str != null) {

     str = br.readLine();

}

br.close();

fr.close();

(7)寫入檔案

FileWriter fw = new FileWriter(str1);

fw.write(str2);

fw.flush();

fw.close();