Android Studio 我的Android应用程序开发项目的JSON解析

cld4siwp  于 2022-11-16  发布在  Android
关注(0)|答案(3)|浏览(153)

我可以在logcat中看到获取的JSON，但它没有显示在我的Activity中，它一直在加载。
我的Web服务的链接是：“http://dcafe-menu.getsandbox.com/dcafe-menu-friday“
FridayMenu.java:

package com.example.nishant.messmenu;

import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.HashMap;

public class FridayMenu extends AppCompatActivity {

    private ProgressDialog pDialog;

    // JSON Node names
    private static final String TAG_FRIDAY = "fridaymenu";
    private static final String TAG_DRY_CEREAL = "DRY_CEREAL";
    private static final String TAG_DRINK_ONE = "DRINK_ONE";
    private static final String TAG_DRINK_TWO = "DRINK_TWO";
    private static final String TAG_MAIN = "MAIN";
    private static final String TAG_ACCOMPANIMENT = "ACCOMPANIMENT";
    private static final String TAG_B_BREAD = "B_BREAD";
    private static final String TAG_L_SALAD = "L_SALAD";
    private static final String TAG_L_RICE = "L_RICE";
    private static final String TAG_L_DAL = "L_DAL";
    private static final String TAG_L_PANEER = "L_PANEER DISH";
    private static final String TAG_L_SEMI = "L_SEMI DRY VEG";
    private static final String TAG_L_GRAVY = "L_GRAVY VEGETABLE";
    private static final String TAG_L_DESSERT = "L_DESSERT";
    private static final String TAG_L_BREAD = "L_BREAD";
    private static final String TAG_L_CURD = "L_CURD";
    private static final String TAG_SNACKS = "SNACKS";
    private static final String TAG_DRINK = "DRINK";
    private static final String TAG_D_SALAD = "D_SALAD";
    private static final String TAG_D_RICE = "D_RICE";
    private static final String TAG_D_DAL = "D_DAL";
    private static final String TAG_D_PANEER = "D_PANEER DISH";
    private static final String TAG_D_SEMI = "D_SEMI DRY VEG";
    private static final String TAG_D_GRAVY = "D_GRAVY VEGETABLE";
    private static final String TAG_D_DESSERT = "D_DESSERT";
    private static final String TAG_D_BREAD = "D_BREAD";
    private static final String TAG_D_CURD = "D_CURD";


    // contacts JSONArray
    JSONArray fridaymenu = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_friday_menu);

        // Calling async task to get json
        new GetContacts().execute();
    }

    /**
     * Async task class to get json by making HTTP call
     * */
    private class GetContacts extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            // Showing progress dialog
            pDialog = new ProgressDialog(FridayMenu.this);
            pDialog.setMessage("Please wait...");
            pDialog.setCancelable(false);
            pDialog.show();

        }

        @Override
        protected Void doInBackground(Void... arg0) {
            // Creating service handler class instance
            ServiceHandler sh = new ServiceHandler();

            // Making a request to url and getting response
            String url = "http://dcafe-menu.getsandbox.com/dcafe-menu-friday";
            String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);

            Log.d("Response: ", "> " + jsonStr);

            if (jsonStr != null) {
                try {
                    JSONObject jsonObj = new JSONObject(jsonStr);
                    // Getting JSON Array node
                    fridaymenu = jsonObj.getJSONArray(TAG_FRIDAY);

                    // looping through All Contacts
                    for (int i = 0; i < fridaymenu.length(); i++) {
                        JSONObject c = fridaymenu.getJSONObject(i);

                        String DRY_CEREAL = c.getString(TAG_DRY_CEREAL);
                        String DRINK_ONE = c.getString(TAG_DRINK_ONE);
                        String DRINK_TWO = c.getString(TAG_DRINK_TWO);
                        String MAIN = c.getString(TAG_MAIN);
                        String ACCOMPANIMENT = c.getString(TAG_ACCOMPANIMENT);
                        String B_BREAD = c.getString(TAG_B_BREAD);
                        String L_SALAD = c.getString(TAG_L_SALAD);
                        String L_RICE = c.getString(TAG_L_RICE);
                        String L_DAL = c.getString(TAG_L_DAL);
                        String L_PANEER = c.getString(TAG_L_PANEER);
                        String L_SEMI = c.getString(TAG_L_SEMI);
                        String L_GRAVY = c.getString(TAG_L_GRAVY);
                        String L_DESSERT = c.getString(TAG_L_DESSERT);
                        String L_BREAD = c.getString(TAG_L_BREAD);
                        String L_CURD = c.getString(TAG_L_CURD);
                        String SNACKS = c.getString(TAG_SNACKS);
                        String DRINK = c.getString(TAG_DRINK);
                        String D_SALAD = c.getString(TAG_D_SALAD);
                        String D_RICE = c.getString(TAG_D_RICE);
                        String D_DAL = c.getString(TAG_D_DAL);
                        String D_PANEER = c.getString(TAG_D_PANEER);
                        String D_SEMI = c.getString(TAG_D_SEMI);
                        String D_GRAVY = c.getString(TAG_D_GRAVY);
                        String D_DESSERT = c.getString(TAG_D_DESSERT);
                        String D_BREAD = c.getString(TAG_D_BREAD);
                        String D_CURD = c.getString(TAG_D_CURD);

                        // tmp hashmap for single contact
                        HashMap<String, String> fridaymenu = new HashMap<String, String>();

                        // adding each child node to HashMap key => value
                        fridaymenu.put(TAG_DRY_CEREAL, DRY_CEREAL);
                        fridaymenu.put(TAG_DRINK_ONE, DRINK_ONE);
                        fridaymenu.put(TAG_DRINK_TWO, DRINK_TWO);
                        fridaymenu.put(TAG_MAIN, MAIN);
                        fridaymenu.put(TAG_ACCOMPANIMENT, ACCOMPANIMENT);
                        fridaymenu.put(TAG_B_BREAD, B_BREAD);
                        fridaymenu.put(TAG_L_SALAD, L_SALAD);
                        fridaymenu.put(TAG_L_RICE, L_RICE);
                        fridaymenu.put(TAG_L_DAL, L_DAL);
                        fridaymenu.put(TAG_L_PANEER, L_PANEER);
                        fridaymenu.put(TAG_L_SEMI, L_SEMI);
                        fridaymenu.put(TAG_L_GRAVY, L_GRAVY);
                        fridaymenu.put(TAG_L_DESSERT, L_DESSERT);
                        fridaymenu.put(TAG_L_BREAD, L_BREAD);
                        fridaymenu.put(TAG_L_CURD, L_CURD);
                        fridaymenu.put(TAG_SNACKS, SNACKS);
                        fridaymenu.put(TAG_DRINK, DRINK);
                        fridaymenu.put(TAG_D_SALAD, D_SALAD);
                        fridaymenu.put(TAG_D_RICE, D_RICE);
                        fridaymenu.put(TAG_D_DAL, D_DAL);
                        fridaymenu.put(TAG_D_PANEER, D_PANEER);
                        fridaymenu.put(TAG_D_SEMI, D_SEMI);
                        fridaymenu.put(TAG_D_GRAVY, D_GRAVY);
                        fridaymenu.put(TAG_D_DESSERT, D_DESSERT);
                        fridaymenu.put(TAG_D_BREAD, D_BREAD);
                        fridaymenu.put(TAG_D_CURD, D_CURD);

                    }

                }
                catch (JSONException e) {
                    e.printStackTrace();
                }
            } else {
                Log.e("ServiceHandler", "Couldn't get any data from the url");
            }

            return null;
        }
    }
}

我可以在logcat中看到JSON，但它没有在我的应用程序中加载。在logcat中可以看到以下内容。当我的Activity开始时，它一直在加载。我已经等了15分钟。但我仍然无法在我的应用程序中看到所需的结果：

11-30 03:10:32.041 9973-10198/com.example.nishant.messmenu W/System.err: org.json.JSONException: No value for L_SALAD
11-30 03:10:32.070 9973-10198/com.example.nishant.messmenu W/System.err:     at org.json.JSONObject.get(JSONObject.java:389)
11-30 03:10:32.071 9973-10198/com.example.nishant.messmenu W/System.err:     at org.json.JSONObject.getString(JSONObject.java:550)
11-30 03:10:32.072 9973-10198/com.example.nishant.messmenu W/System.err:     at com.example.nishant.messmenu.FridayMenu$GetContacts.doInBackground(FridayMenu.java:109)
11-30 03:10:32.072 9973-10198/com.example.nishant.messmenu W/System.err:     at com.example.nishant.messmenu.FridayMenu$GetContacts.doInBackground(FridayMenu.java:68)
11-30 03:10:32.072 9973-10198/com.example.nishant.messmenu W/System.err:     at android.os.AsyncTask$2.call(AsyncTask.java:304)
11-30 03:10:32.072 9973-10198/com.example.nishant.messmenu W/System.err:     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
11-30 03:10:32.072 9973-10198/com.example.nishant.messmenu W/System.err:     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:243)
11-30 03:10:32.072 9973-10198/com.example.nishant.messmenu W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
11-30 03:10:32.072 9973-10198/com.example.nishant.messmenu W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
11-30 03:10:32.072 9973-10198/com.example.nishant.messmenu W/System.err:     at java.lang.Thread.run(Thread.java:761)
android-studio

3条答案

按热度按时间
pu3pd22g

pu3pd22g1#

为此只需做两件事：
在所有Json获取对象时，不要使用“get”，而要使用“opt”：

String DRY_CEREAL = c.optString(TAG_DRY_CEREAL);

第二，在hashmap中使用以下代码：

If(DRY_CEREAL==null||DRY_CEREAL.isEmpty())
 {
        fridaymenu.put(TAG_DRY_CEREAL, " ");
 }
 else
 {
        fridaymenu.put(TAG_DRY_CEREAL, DRY_CEREAL);
 }

对每个散列表条目都这样做，它将解决您的问题。

赞(0）分享  回复(0）举报  2022-11-16
velaa5lx

velaa5lx2#

必须使用“opt”代替“get”，并使用默认回退值
这是他们之间的区别：

getString(String name)

Returns the value mapped by name if it exists, coercing it if necessary, or throws if no such mapping exists. 

 optString(String name, String fallback)

 Returns the value mapped by name if it exists, coercing it if necessary, or fallback if no such mapping exists.

例如在你的情况：
电流

String L_SALAD = c.getString(TAG_L_SALAD);

改为：

String L_SALAD = c.optString(TAG_L_SALAD,"");

对每个人都做同样的事情。我希望你的问题会得到解决。

赞(0）分享  回复(0）举报  2022-11-16
t2a7ltrp

t2a7ltrp3#

它持续加载的原因是，你没有隐藏进度条。

@Override
    protected void onPostExecute(Void aVoid) {
        super.onPostExecute(aVoid);
        pDialog.hide();
    }
赞(0）分享  回复(0）举报  2022-11-16
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