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如果arraylist为空,如何保存到shredReferences?

sharedpreferences arraylist java

CHarris · 技术社区 · 5 年前

arraylist , MatchingArrayList ,从我的服务器:

        try {
          JSONArray Object = new JSONArray(MatchingAsString);
          //for every object in the Array
          for (int x = 0; x < Object.length(); x++) {
            final JSONObject obj = Object.getJSONObject(x);
            MatchingArrayList.add(obj.getString("usernameMatch"));
            }

[+111, +222]

数组表 到 sharedpreferences

            SharedPreferences sharedPreferencesMAL = PreferenceManager.getDefaultSharedPreferences(getApplication());
            SharedPreferences.Editor editorMAL = sharedPreferencesMAL.edit();
            Gson gsonMAL = new Gson();
            String jsonMAL = gsonMAL.toJson(MatchingArrayList);
            editorMAL.putString("MatchingArrayList", jsonMAL);
            editorMAL.commit();

所以下一次使用应用程序时,如果 匹配ArrayList [+111, +222, +333] ,例如,它将覆盖上次使用的 数组表 属于 [+111, +222]

匹配ArrayList null 或者是空的。这个不更新。我试过:

          if (MatchingArrayList == null) {

            SharedPreferences sharedPreferencesMAL = PreferenceManager.getDefaultSharedPreferences(getApplication());
            SharedPreferences.Editor editorMAL = sharedPreferencesMAL.edit();
            editorMAL.putString("MatchingArrayList", null);
            editorMAL.commit();
          } else {

            //save MatchingArrayList into sharedpreferences so we can use it elsewhere
            SharedPreferences sharedPreferencesMAL = PreferenceManager.getDefaultSharedPreferences(getApplication());
            SharedPreferences.Editor editorMAL = sharedPreferencesMAL.edit();
            Gson gsonMAL = new Gson();
            String jsonMAL = gsonMAL.toJson(MatchingArrayList);
            editorMAL.putString("MatchingArrayList", jsonMAL);
            editorMAL.commit();

          }

  But still the last arraylist is being used. How can I fix this?

0 回复 | 直到 5 年前

CHarris 5 年前

而不是看我的java arraylist response php 我的应用程序的侧面。这样地:

          if (response.isEmpty()) {

            SharedPreferences sharedPreferencesMatchingContactsAsArrayList = PreferenceManager.getDefaultSharedPreferences(getApplication());
            SharedPreferences.Editor editorMatchingContactsAsArrayList = sharedPreferencesMatchingContactsAsArrayList.edit();
            editorMatchingContactsAsArrayList.putString("MatchingContactsAsArrayList", "");
            editorMatchingContactsAsArrayList.commit();
          } else {

解决了我的问题,更新了 sharedpreferences .