android开发错误笔记

整理错误

The Android Gradle plugin supports only Kotlin Gradle plugin version 1.2.51 and higher. Project '项目名' is using version 1.1.51.

解决方式 在最外层build.gradle 中修改

    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.2.51"
    }
}

Android app\build\intermediates\res\merged\debug\values-vXX\values-vXX.xml
解决方法

app build.gradle中 compileSdkVersion  buildToolsVersion targetSdkVersion一致

Anderoid List转json字符串

        JSONArray jsonArray = new JSONArray();
        JSONObject jsonObject = new JSONObject();
        JSONObject tmpObj = null;
        int count = anwerList.size();
        for (int i = 0; i < count; i++) {
            tmpObj = new JSONObject();
            try {
                tmpObj.put("QuestionType", anwerList.get(i).get("type"));
            } catch (JSONException e) {
                e.printStackTrace();
            }
            try {
                tmpObj.put("CorrectAnswer", anwerList.get(i).get("answer"));
            } catch (JSONException e) {
                e.printStackTrace();
            }
            try {
                tmpObj.put("QuestionNum",Integer.parseInt(i+1+""));
            } catch (JSONException e) {
                e.printStackTrace();
            }


            jsonArray.put(tmpObj);
            tmpObj = null;
        }
        String personInfos = jsonArray.toString(); // 将JSONArray转换得到String

4.Android json字符串的读取

  JsonArray returnData = new JsonParser().parse(dataStr).getAsJsonArray();
            for (int i = 0; i < returnData.size(); i++) {

                String type = returnData.get(i).getAsJsonObject().get("QuestionType").getAsString();
                String answer = returnData.get(i).getAsJsonObject().get("CorrectAnswer").getAsString();
                Dictionary<String, String> hashTable = new Hashtable<String, String>();
                hashTable.put("type", type);
                hashTable.put("answer", answer);
                hashTable.put("num", i + 1 + "");
            }