如何从Fragment中更改QueryUtils文件中存在的json对象的索引值？
这一部分就在这里：JSONObject currentDay = dayArray.getJSONObject(0);
我想要为每个片段更改索引值，但无法绕过它。我尝试过Intent并创建一个构造函数但是失败了。
就像现在一样，应用程序正在“运行”所有显示星期一时间表的片段（JSONObject索引0）。
QueryUtils.java
import android.text.TextUtils;
import android.util.Log;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
public final class QueryUtils {
private static final String LOG_TAG = QueryUtils.class.getSimpleName();
//makeHttpRequest constants
private static final int READ_TIMEOUT = 10000 /* milliseconds */;
private static final int CONNECT_TIMEOUT = 15000 /* milliseconds */;
private static final int RESPONSE_CODE = 200 /*everything is OK*/;
public QueryUtils() {
}
public static List<Day> fetchDayData(String requestUrl) {
URL url = createUrl(requestUrl);
String jsonResponse = null;
try {
jsonResponse = makeHttpRequest(url);
} catch (IOException e) {
Log.e(LOG_TAG, "Problem making the HTTP request.", e);
}
List<Day> days = extractFeatureFromJson(jsonResponse);
return days;
}
private static URL createUrl(String stringUrl) {
URL url = null;
try {
url = new URL(stringUrl);
} catch (MalformedURLException e) {
Log.e(LOG_TAG, "Problem building the URL ", e);
}
return url;
}
private static String makeHttpRequest(URL url) throws IOException {
String jsonResponse = "";
if (url == null) {
return jsonResponse;
}
HttpURLConnection urlConnection = null;
InputStream inputStream = null;
try {
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setReadTimeout(READ_TIMEOUT);
urlConnection.setConnectTimeout(CONNECT_TIMEOUT);
urlConnection.setRequestMethod("GET");
urlConnection.connect();
if (urlConnection.getResponseCode() == RESPONSE_CODE) {
inputStream = urlConnection.getInputStream();
jsonResponse = readFromStream(inputStream);
} else {
Log.e(LOG_TAG, "Error response code: " + urlConnection.getResponseCode());
}
} catch (IOException e) {
Log.e(LOG_TAG, "Problem retrieving Berceni JSON results.", e);
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (inputStream != null) {
inputStream.close();
}
}
return jsonResponse;
}
private static String readFromStream(InputStream inputStream) throws IOException {
StringBuilder output = new StringBuilder();
if (inputStream != null) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream, Charset.forName("UTF-8"));
BufferedReader reader = new BufferedReader(inputStreamReader);
String line = reader.readLine();
while (line != null) {
output.append(line);
line = reader.readLine();
}
}
return output.toString();
}
private static List<Day> extractFeatureFromJson(String dayJSON) {
if (TextUtils.isEmpty(dayJSON)) {
return null;
}
List<Day> days = new ArrayList<>();
//Try to parse
try {
JSONObject baseJsonResponse = new JSONObject(dayJSON);
JSONArray dayArray = baseJsonResponse.getJSONObject("schedule").getJSONArray("day");
JSONObject currentDay = dayArray.getJSONObject(0);
JSONArray getClasses = currentDay.getJSONArray("classes");
for (int j = 0; j < getClasses.length(); j++) {
JSONObject currentClass = getClasses.getJSONObject(j);
String retrieveCourseTitle = currentClass.getString("class");
String retrieveCourseTime = currentClass.getString("time");
String retrieveCourseTrainer = currentClass.getString("trainer");
String retrieveCourseCancelState = currentClass.getString("canceled");
Day day = new Day(retrieveCourseTitle, retrieveCourseTime, retrieveCourseTrainer, retrieveCourseCancelState);
days.add(day);
}
} catch (JSONException e) {
// If an error is thrown when executing any of the above statements in the "try" block,
// catch the exception here, so the app doesn't crash. Print a log message
// with the message from the exception.
Log.e("QueryUtils", "Problem parsing JSON results", e);
}
return days;
}
}
和我的FragmentAdapter.java
import android.content.Context;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
public class FragmentAdapter extends FragmentPagerAdapter {
private Context mContext;
public FragmentAdapter(Context context, FragmentManager fm) {
super(fm);
mContext = context;
}
@Override
public Fragment getItem(int position) {
if (position == 0) {
return new MondayFragment();
} else if (position == 1) {
return new ThursdayFragment();
} else if (position == 2) {
return new WednesdayFragment();
} else if (position == 3) {
return new ThursdayFragment();
} else if (position == 4) {
return new FridayFragment();
} else if (position == 5) {
return new SaturdayFragment();
} else {
return new SundayFragment();
}
}
/**
* Return the total number of pages.
*/
@Override
public int getCount() {
return 7;
}
@Override
public CharSequence getPageTitle(int position) {
if (position == 0) {
return mContext.getString(R.string.monday);
} else if (position == 1) {
return mContext.getString(R.string.tuesday);
} else if (position == 2) {
return mContext.getString(R.string.wednesday);
} else if (position == 3) {
return mContext.getString(R.string.thursday);
} else if (position == 4) {
return mContext.getString(R.string.friday);
} else if (position == 5) {
return mContext.getString(R.string.saturday);
} else {
return mContext.getString(R.string.sunday);
}
}
}
JSON示例响应
{
"schedule":{
"day":[
{
"id":"Monday",
"classes":[
{
"class" : "Class",
"time" : "00:00",
"trainer" : "Teacher",
"canceled" : ""
},
{
"class" : "Class",
"time" : "00:00",
"trainer" : "Teacher",
"canceled" : ""
}
]
},
{
"id":"Tuesday",
"classes":[
{
"class" : "Class",
"time" : "00:00",
"trainer" : "Teacher",
"canceled" : ""
},
{
"class" : "Class",
"time" : "00:00",
"trainer" : "Teacher",
"canceled" : ""
}
]
},
{
"id":"Wednesday",
"classes":[
{
"class" : "Class",
"time" : "00:00",
"trainer" : "Teacher",
"canceled" : ""
},
{
"class" : "Class",
"time" : "00:00",
"trainer" : "Teacher",
"canceled" : ""
}
]
},
{
"id":"Thursday",
"classes":[
{
"class" : "Class",
"time" : "00:00",
"trainer" : "Teacher",
"canceled" : ""
},
{
"class" : "Class",
"time" : "00:00",
"trainer" : "Teacher",
"canceled" : ""
}
]
},
{
"id":"Friday",
"classes":[
{
"class" : "Class",
"time" : "00:00",
"trainer" : "Teacher",
"canceled" : ""
},
{
"class" : "Class",
"time" : "00:00",
"trainer" : "Teacher",
"canceled" : ""
}
]
},
{
"id":"Saturday",
"classes":[
{
"class" : "Class",
"time" : "00:00",
"trainer" : "Teacher",
"canceled" : ""
},
{
"class" : "Class",
"time" : "00:00",
"trainer" : "Teacher",
"canceled" : ""
}
]
},
{
"id":"Sunday",
"classes":[]
}
]
}
}
答案 0 :(得分：1)
查看您的POJO并不明确等于您的JSON。
一天应宣布为：
class Day {
String id;
List<ClassDetail> classes;
}
class ClassDetail {
//all the details
}
我认为你错过了接受你的功能，跟随签名不太明确。
List<Day> extractFeatureFromJson(String dayJSON)
为了使其更具可读性，我建议将其更改为：
（您可以使用Hashmap as recommended for @ρяσѕρєя）：
HashMap<String, ClassDetail> parseScheduleJson(String scheduleJSON)
并将每个ClassDetail添加到结果
@Nullable
private static Map<String, List<ClassDetail>> parseScheduleJson(String scheduleJSON) {
if (TextUtils.isEmpty(scheduleJSON)) {
return null;
}
HashMap<String, List<ClassDetail>> result = new HashMap<>();
try {
JSONObject baseJsonResponse = new JSONObject(scheduleJSON);
JSONArray dayArray = baseJsonResponse.getJSONObject("schedule").getJSONArray("day");
for (int i = 0; i < dayArray.length(); i++) {
ArrayList<ClassDetail> classes = new ArrayList<>();
JSONObject currentDay = dayArray.getJSONObject(i);
for (int j = 0; j < currentDay.getJSONArray("classes").length(); j++) {
JSONObject currentClass = currentDay.getJSONArray("classes").getJSONObject(j);
String retrieveCourseTitle = currentClass.getString("class");
String retrieveCourseTime = currentClass.getString("time");
String retrieveCourseTrainer = currentClass.getString("trainer");
String retrieveCourseCancelState = currentClass.getString("canceled");
classes.add(new ClassDetail(retrieveCourseTitle, retrieveCourseTime, retrieveCourseTrainer, retrieveCourseCancelState));
}
result.put(currentDay.getString("id"), classes);
}
} catch (JSONException e) {
// If an error is thrown when executing any of the above statements in the "try" block,
// catch the exception here, so the app doesn't crash. Print a log message
// with the message from the exception.
Log.e("QueryUtils", "Problem parsing JSON results", e);
return null;
}
return result;
}
在此之后，您可以使用以下方式访问当天的课程列表：
mymap.get("Monday");
mymap.get("Tuesday");
...
mymap.get("Sunday");
修改
恕我直言，您必须在活动中调用您的日常活动，并将地图结果注入您的FragmentPagerAdapter：
public FragmentAdapter(Context context, FragmentManager fm, Map<String, List<ClassDetail> schedule) {
super(fm);
mContext = context;
mSchedule = schedule;
}
@Override
public Fragment getItem(int position) {
if (position == 0) {
return MondayFragment.newInstance(mSchedule.get("Monday"));
//...
//same for all conditions
//...
} else {
return SundayFragment.newInstance(mSchedule.get("Sunday"));
}
}
在使用newIntance pattern之后，您可以将片段声明为：
private List<ClassDetail> mClasses;
public static MondayClassDetailFragment newInstance(ArrayList<ClassDetail> classes){
MondayClassDetailFragment myFragment = new MondayClassDetailFragment();
Bundle args = new Bundle();
args.putParcelableArrayList("classes", classes);
myFragment.setArguments(args);
return myFragment;
}
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mClasses = getArguments().getParcelableArrayList("classes");
}
PS：在这些日子里手动发出http请求和解析json是浪费精力。我建议你去看一下图书馆这样做，特别是那些被广泛使用并且记录良好的retrofit。
答案 1 :(得分：0)
我不确定这是因为我从未使用FragmentPagerAdapter，但我认为它在概念上与任何Adapter一样有效。
我在您的代码中注意到的是您的代码（请参阅注释）
private static List<Day> extractFeatureFromJson(String dayJSON) {
if (TextUtils.isEmpty(dayJSON)) {
return null;
}
List<Day> days = new ArrayList<>();
//Try to parse
try {
JSONObject baseJsonResponse = new JSONObject(dayJSON);
JSONArray dayArray = baseJsonResponse.getJSONObject("schedule").getJSONArray("day");
JSONObject currentDay = dayArray.getJSONObject(0); //<<<<<<HERE
JSONArray getClasses = currentDay.getJSONArray("classes");
for (int j = 0; j < getClasses.length(); j++) {
JSONObject currentClass = getClasses.getJSONObject(j);
String retrieveCourseTitle = currentClass.getString("class");
String retrieveCourseTime = currentClass.getString("time");
String retrieveCourseTrainer = currentClass.getString("trainer");
String retrieveCourseCancelState = currentClass.getString("canceled");
Day day = new Day(retrieveCourseTitle, retrieveCourseTime, retrieveCourseTrainer, retrieveCourseCancelState);
days.add(day);
}
} catch (JSONException e) {
// If an error is thrown when executing any of the above statements in the "try" block,
// catch the exception here, so the app doesn't crash. Print a log message
// with the message from the exception.
Log.e("QueryUtils", "Problem parsing JSON results", e);
}
return days;
}
你正在进行＆＃34;提取＆＃34;仅适用于JSONObject currentDay = dayArray.getJSONObject(0);
这意味着您的List<Day> days只有一个Day，即当天。假设您将此List提供给适配器，则只找到Day，因此没有任何变化。
我建议您遍历所有日子，每天将List添加到try{
JSONObject baseJsonResponse = new JSONObject(dayJSON);
JSONArray dayArray = baseJsonResponse.getJSONObject("schedule").getJSONArray("day");
for (int i = 0; i<dayArray.length();i++){
JSONObject currentDay = dayArray.getJSONObject(i);
//the rest
}
}catch(JSONException e){
//etc
}
，如下所示：
constructor() {
this.calcArray(500);
}
calcArray(value: number) {
const difference = Math.abs(this.max - value);
this.data = {
datasets: [
{
data: [
difference, value
],
backgroundColor: [
'#FF6384',
'#36A2EB'
],
hoverBackgroundColor: [
'#FF6384',
'#36A2EB'
]
}]
};
}
答案 2 :(得分：0)
虽然@crgarridos的回答是有效的，但我一直在考虑以最少的代码修改来实现我的目标的更快更方便的方法，所以：
我最终修改了我的JSON API并为 id 键创建了查询网址，以便我可以这样查询：
URL?id=monday。
接下来我只需要为每个片段添加一个URI构建器和appendQueryParameter(key, value);。