ファイルにデータを書き込むか、ファイルの内容を読み取る

static public String ReadActivityFile(Context aContext, String aFile) {
		String buffer="";
		FileInputStream in2;
			try {
				in2 = aContext.openFileInput(aFile);
				
				InputStreamReader inReader = new InputStreamReader(in2);
				int buf= 1024;
				BufferedReader line = new BufferedReader(inReader,buf);
				String tmpBuffer = "";
					while ((tmpBuffer = line.readLine()) != null) {
						buffer += tmpBuffer;
					}
				line.close();
				inReader.close();
				in2.close();
			} catch (FileNotFoundException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			}
		return buffer;
	}

	static public void WriteActivityFile(Context aContext, String aFile,
			String aBuffer) {
		try {
			FileOutputStream os = aContext.openFileOutput(aFile,
					Context.MODE_WORLD_READABLE + Context.MODE_WORLD_WRITEABLE);
			OutputStreamWriter outWriter = new OutputStreamWriter(os);

			outWriter.write(aBuffer, 0, aBuffer.length());
			outWriter.flush();
			outWriter.close();
			os.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

必要な場所で呼び出せばいいので、必要なパラメータを完了します.
読み込み:

	String buffer = "";
					buffer = FileUtils.ReadActivityFile(ScoreActivity.this,
							common.FAVORITE_DATA_FILE);

書き込み:

FileUtils.WriteActivityFile(ScoreActivity.this,
								common.FAVORITE_DATA_FILE, buffer);

 
 
次の例は、一度クリックして、このデータをファイルに保存してから、もう一度クリックして、保存を取り消して、ファイルから削除します.

LinearLayout ly = (LinearLayout) layout
					.findViewById(R.id.linear_score_choise);
			ly.setOnClickListener(new OnClickListener() {
				public void onClick(View arg0) {

					String buffer = "";
					buffer = FileUtils.ReadActivityFile(ScoreActivity.this,
							common.FAVORITE_DATA_FILE);
					boolean isFileBlank = false;
					if (buffer.length() <= 0) {
						//  buffer ， true；
						isFileBlank = true;
					}
					boolean has_fav = false;
					//  buffer 
					if (!isFileBlank) {
						//  
						Vector fav_list = CommonUtil.Split(buffer, ",");
						buffer = "";// buffer 

						for (int i = 0; i < fav_list.size(); i++) {
							String fav_id = (String) fav_list.elementAt(i);
							// System.out.println(fav_id);
							if (fav_id.equals(mId)) {
								has_fav = true;
								continue;
							}
							if (fav_id.length() <= 0) {
								continue;
							}
							buffer += fav_id;
							if (i != fav_list.size() - 1) {
								buffer += ",";
							}
						}
					}
					if (buffer.length() > 0
							&& buffer.charAt(buffer.length() - 1) == ',') {
						buffer = buffer.substring(0, buffer.length() - 1);
					}
					if (has_fav) {
						//  
						imageView.setImageResource(R.drawable.gray_star);
						Toast.makeText(ScoreActivity.this, " ！",
								Toast.LENGTH_SHORT).show();
						FileUtils.WriteActivityFile(ScoreActivity.this,
								common.FAVORITE_DATA_FILE, buffer);
					} else {
						//  
						if (!isFileBlank) {//  buffer 
							buffer += ",";
						}
						buffer += mId;
						imageView.setImageResource(R.drawable.yellow_star);
						Toast.makeText(ScoreActivity.this, " ！",
								Toast.LENGTH_SHORT).show();
						FileUtils.WriteActivityFile(ScoreActivity.this,
								common.FAVORITE_DATA_FILE, buffer);
					}
				}
			});