Java 正在将重复值添加到ArrayList

我已经创建了一个自定义列表适配器，并且正在尝试从SQLite数据库中列出数据。“我的列表”正在输出正确数量的数据库记录，但已将最终的数据库项复制了许多倍，与数据库中的项目数量相同

我有以下代码：

    private class JSONParse extends AsyncTask<String, String, JSONArray> {

    @Override
    protected JSONArray doInBackground(String... args) {
        JSONArray arr = null;
        db = new DatabaseHandler(getActivity());
        arr = db.getSynced();
        db.close();
        DiaryItems diary = new DiaryItems();
        try {
            for (int i = 0; i < arr.length(); i++) {
                JSONObject c = arr.getJSONObject(i);
                String ass_id = c.getString(TAG_ASSID);
                String time = c.getString(TAG_TIME);
                String cname = c.getString(TAG_CNAME);
                String cno = c.getString(TAG_CNO);
                String type = c.getString(TAG_TYPE);
                String complete = c.getString(TAG_COMPLETE);
                System.out.println("ASS ID: " + ass_id); //works - prints ass_id 1->10
                diary.setAss_id(ass_id);
                diary.setTime(time);
                diary.setCname(cname);
                diary.setCno(cno);
                diary.setType(type);
                diary.setComplete(complete);
                diaryList.add(diary);
            }
            for (int j = 0; j < diaryList.size(); j++) {
                System.out.println("ASSIGN ID: " + diaryList.get(j).getAss_id());
                //this prints this correct size of items, but the array only contains 
                //the values of the last item parsed in the JSON
            }

        } catch (JSONException e) {
            e.printStackTrace();
        }
        return arr;
    }

    @Override
    protected void onPostExecute(JSONArray array) {
        if (dialog.isShowing()) {
            System.out.println("Dismissed dialog");
            dialog.dismiss();
        }
        if (diaryList != null) {
            DiaryListAdapter adapter = new DiaryListAdapter(getActivity(), diaryList);
            getListView().setAdapter(adapter);
        }

    }
}

您正在将同一个DiaryItems实例多次添加到列表中。您应该在循环的每个迭代中创建一个新的DiaryItems实例

改变

    DiaryItems diary = new DiaryItems();
    try {
        for (int i = 0; i < arr.length(); i++) {
            ....

到

您已经实例化了DiaryItems diary=new DiaryItems； 在for循环之外。在循环中创建它，而不是每次循环结束时都添加它。尝试：

for (int i = 0; i < arr.length(); i++) {
    DiaryItems diary = new DiaryItems();
    ..do stuff
}

而不是：

DiaryItems diary = new DiaryItems();
        try {
            for (int i = 0; i < arr.length(); i++) {
                JSONObject c = arr.getJSONObject(i);

---

您已经在for循环外部实例化了日记对象，因此在每次迭代中最终都会设置相同的实例

DiaryItems diary = new DiaryItems();
        try {
            for (int i = 0; i < arr.length(); i++) {
                JSONObject c = arr.getJSONObject(i);