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每次有人在我的應用程序中進行事務處理時，我想使用json/gson將其保存到本地存儲中。我相信我快到了，但是我的問題是每次寫入時都正確格式化json文件。如何創建格式正確的gson對象數組
我想每次創建一個Transaction對象時追加到文件中，然後在某個時刻從文件中讀取每個Transaction對象以便在列表中顯示。以下是我迄今爲止：
public void saveTransaction(Transaction transaction)
throws JSONException, IOException {
Gson gson = new Gson();
String json = gson.toJson(transaction);
//Write the file to disk
Writer writer = null;
try {
OutputStream out = mContext.openFileOutput(mFilename, Context.MODE_APPEND);
writer = new OutputStreamWriter(out);
writer.write(json);
} finally {
if (writer != null)
writer.close();
}
}
我的交易對象有一個量，一個用戶ID和一個布爾值，與此代碼我可以閱讀以下JSON字符串寫入：
{"mAmount":"12.34","mIsAdd":"true","mUID":"76163164"}
{"mAmount":"56.78","mIsAdd":"true","mUID":"76163164"}
我讀取這些值，像這樣，但只能讀取第一個（我猜是因爲他們不是在一個陣列/格式正確的JSON對象）：
public ArrayList<Transaction> loadTransactions() throws IOException, JSONException {
ArrayList<Transaction> allTransactions = new ArrayList<Transaction>();
BufferedReader reader = null;
try {
//Open and read the file into a string builder
InputStream in = mContext.openFileInput(mFilename);
reader = new BufferedReader(new InputStreamReader(in));
StringBuilder jsonString = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
//Line breaks are omitted and irrelevant
jsonString.append(line);
}
//Extract every Transaction from the jsonString here -----
} catch (FileNotFoundException e) {
//Ignore this one, happens when launching for the first time
} finally {
if (reader != null)
reader.close();
}
return allTransactions;
}