我是Android的新手,并尝试使用JsON制作多级ListVIEw,
在我的情况下,我想只使用JsON实现这一点：类别>项目>详情
但我在第一个屏幕上遇到问题,甚至无法获取类别
JsON：
{ "categoryID": "1","categoryTitle": { "SmartPhones": [ { "itemID": "1","itemTitle": "galaxy Mega 5.8" },{ "itemID": "2","itemTitle": "galaxy Mega 6.3" } ] },"categoryID": "2","categoryTitle": { "tablets": [ { "itemID": "1","itemTitle": "galaxy Note 510" },{ "itemID": "2","itemTitle": "galaxy Note 800" } ]}} 谢谢@Segi给我正确的JsON格式
活动代码：
public class CategorIEsActivity extends ListActivity {// Connection detectorConnectionDetector cd;// Alert dialog managerAlertDialogManager alert = new AlertDialogManager();// Progress Dialogprivate ProgressDialog pDialog;// Creating JsON Parser objectJsONParser JsonParser = new JsONParser();ArrayList<HashMap<String,String>> categorIEsList;// albums JsONArrayJsONArray categorIEs = null;// albums JsON urlprivate static final String URL_CATEGORIES = "my.Json"; // provIDing proper URL// ALL JsON node namesprivate static final String TAG_ID = "categoryID";private static final String TAG_Title = "categoryTitle";@OverrIDepublic voID onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentVIEw(R.layout.activity_albums); cd = new ConnectionDetector(getApplicationContext()); // Check for internet connection if (!cd.isConnectingToInternet()) { // Internet Connection is not present alert.showAlertDialog(CategorIEsActivity.this,"Internet Connection Error","Please connect to working Internet connection",false); // stop executing code by return return; } // Hashmap for ListVIEw categorIEsList = new ArrayList<HashMap<String,String>>(); // Loading CategorIEs JsON in Background Thread new LoadCategorIEs().execute(); // get ListvIEw ListVIEw lv = getListVIEw(); /** * ListvIEw item click Listener * ProductListActivity will be lauched by passing category ID * */ lv.setonItemClickListener(new androID.Widget.AdapterVIEw.OnItemClickListener() { @OverrIDe public voID onItemClick(AdapterVIEw<?> arg0,VIEw vIEw,int arg2,long arg3) { // on selecting a single category // ProductListActivity will be launched to show products insIDe the category Intent i = new Intent(getApplicationContext(),TrackListActivity.class); // send category ID to productList activity to get List of products under that category String category_ID = ((TextVIEw) vIEw.findVIEwByID(R.ID.album_ID)).getText().toString(); i.putExtra("category_ID",category_ID); startActivity(i); } }); }/** * Background Async Task to Load all CategorIEs by making http request * */class LoadCategorIEs extends AsyncTask<String,String,String> { /** * Before starting background thread Show Progress Dialog * */ @OverrIDe protected voID onPreExecute() { super.onPreExecute(); pDialog = new ProgressDialog(CategorIEsActivity.this); pDialog.setMessage("Listing CategorIEs ..."); pDialog.setIndeterminate(false); pDialog.setCancelable(false); pDialog.show(); } /** * getting CategorIEs JsON * */ protected String doInBackground(String... args) { // Building Parameters List<nameValuePair> params = new ArrayList<nameValuePair>(); // getting JsON string from URL String Json = JsonParser.makehttpRequest(URL_CATEGORIES,"GET",params); // Check your log cat for JsON reponse Log.d("CategorIEs JsON: ","> " + Json); try { categorIEs = new JsONArray(Json); if (categorIEs != null) { // looPing through all categorIEs for (int i = 0; i < categorIEs.length(); i++) { JsONObject c = categorIEs.getJsONObject(i); // Storing each Json item values in variable String ID = c.getString(TAG_ID); String Title = c.getString(TAG_Title); // creating new HashMap HashMap<String,String> map = new HashMap<String,String>(); // adding each child node to HashMap key => value map.put(TAG_ID,ID); map.put(TAG_Title,Title); // adding HashList to ArrayList categorIEsList.add(map); } }else{ Log.d("CategorIEs: ","null"); } } catch (JsONException e) { e.printstacktrace(); } return null; } /** * After completing background task dismiss the progress dialog * **/ protected voID onPostExecute(String file_url) { // dismiss the dialog after getting all categorIEs pDialog.dismiss(); // updating UI from Background Thread runOnUiThread(new Runnable() { public voID run() { /** * Updating parsed JsON data into ListVIEw * */ listadapter adapter = new SimpleAdapter( CategorIEsActivity.this,categorIEsList,R.layout.List_item_albums,new String[] { TAG_ID,TAG_Title },new int[] { R.ID.category_ID,R.ID.category_Title }); // updating ListvIEw setlistadapter(adapter); } }); } }} logcat的：
06-15 12:21:27.124: D/dalvikvm(786): GC_FOR_ALLOC freed 68K,8% free 2488K/2680K,paused 173ms,total 213ms06-15 12:21:27.174: I/dalvikvm-heap(786): Grow heap (frag case) to 3.152MB for 635812-byte allocation06-15 12:21:27.264: D/dalvikvm(786): GC_FOR_ALLOC freed 1K,6% free 3108K/3304K,paused 89ms,total 89ms06-15 12:21:27.354: D/dalvikvm(786): GC_CONCURRENT freed <1K,6% free 3111K/3304K,paused 5ms+3ms,total 95ms06-15 12:21:28.274: I/Choreographer(786): Skipped 41 frames! The application may be doing too much work on its main thread.06-15 12:21:28.874: I/Choreographer(786): Skipped 123 frames! The application may be doing too much work on its main thread.06-15 12:21:29.044: D/gralloc_goldfish(786): Emulator without GPU emulation detected.06-15 12:21:29.134: D/dalvikvm(786): GC_CONCURRENT freed 19K,4% free 3478K/3620K,paused 8ms+38ms,total 268ms06-15 12:21:30.894: I/Choreographer(786): Skipped 51 frames! The application may be doing too much work on its main thread.06-15 12:20:36.624: D/CategorIEs JsON:(786): > {06-15 12:20:36.624: D/CategorIEs JsON:(786): "categoryID": "1",06-15 12:20:36.624: D/CategorIEs JsON:(786): "categoryTitle": {06-15 12:20:36.624: D/CategorIEs JsON:(786): "SmartPhones": [06-15 12:20:36.624: D/CategorIEs JsON:(786): {06-15 12:20:36.624: D/CategorIEs JsON:(786): "itemID": "1",06-15 12:20:36.624: D/CategorIEs JsON:(786): "itemTitle": "galaxy Mega 5.8"06-15 12:20:36.624: D/CategorIEs JsON:(786): },06-15 12:20:36.624: D/CategorIEs JsON:(786): {06-15 12:20:36.624: D/CategorIEs JsON:(786): "itemID": "2",06-15 12:20:36.624: D/CategorIEs JsON:(786): "itemTitle": "galaxy Mega 6.3"06-15 12:20:36.624: D/CategorIEs JsON:(786): }06-15 12:20:36.624: D/CategorIEs JsON:(786): ]06-15 12:20:36.624: D/CategorIEs JsON:(786): },06-15 12:20:36.624: D/CategorIEs JsON:(786): "categoryID": "2",06-15 12:20:36.624: D/CategorIEs JsON:(786): "categoryTitle": {"tablets": [06-15 12:20:36.624: D/CategorIEs JsON:(786): {06-15 12:20:36.624: D/CategorIEs JsON:(786): "itemID": "1",06-15 12:20:36.624: D/CategorIEs JsON:(786): "itemTitle": "galaxy Note 510"06-15 12:20:36.624: D/CategorIEs JsON:(786): },06-15 12:20:36.624: D/CategorIEs JsON:(786): {06-15 12:20:36.624: D/CategorIEs JsON:(786): "itemID": "2",06-15 12:20:36.624: D/CategorIEs JsON:(786): "itemTitle": "galaxy Note 800"06-15 12:20:36.624: D/CategorIEs JsON:(786): }06-15 12:20:36.624: D/CategorIEs JsON:(786): ]}06-15 12:20:36.624: D/CategorIEs JsON:(786): }06-15 12:20:36.814: W/System.err(786): org.Json.JsONException: Value {"categoryTitle":{"SmartPhones":[{"itemID":"1","itemTitle":"galaxy Mega 5.8"},{"itemID":"2","itemTitle":"galaxy Mega 6.3"}]},"categoryID":"2"} of type org.Json.JsONObject cannot be converted to JsONArray06-15 12:20:36.824: W/System.err(786): at org.Json.JsON.typeMismatch(JsON.java:111)06-15 12:20:36.836: W/System.err(786): at org.Json.JsONArray.<init>(JsONArray.java:91)06-15 12:20:36.836: W/System.err(786): at org.Json.JsONArray.<init>(JsONArray.java:103)06-15 12:20:36.904: W/System.err(786): at com.my.Json.CategorIEsActivity$LoadCategorIEs.doInBackground(CategorIEsActivity.java:135)06-15 12:20:36.904: W/System.err(786): at com.my.Json.CategorIEsActivity$LoadCategorIEs.doInBackground(CategorIEsActivity.java:1)06-15 12:20:36.914: W/System.err(786): at androID.os.AsyncTask.call(AsyncTask.java:287)06-15 12:20:36.914: W/System.err(786): at java.util.concurrent.FutureTask.run(FutureTask.java:234)06-15 12:20:36.925: W/System.err(786): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)06-15 12:20:36.925: W/System.err(786): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)06-15 12:20:36.934: W/System.err(786): at java.lang.Thread.run(Thread.java:856)06-15 12:20:45.984: D/inputEventConsistencyVerifIEr(786): KeyEvent: ACTION_UP but key was not down.06-15 12:20:45.984: D/inputEventConsistencyVerifIEr(786): in androID.vIEw.VIEwRootImpl@40de89c806-15 12:20:45.984: D/inputEventConsistencyVerifIEr(786): 0: sent at 106936000000,KeyEvent { action=ACTION_UP,keyCode=KEYCODE_MENU,scanCode=229,MetaState=0,flags=0x8,repeatCount=0,eventTime=106936,downTime=106820,deviceid=0,source=0x101 } 注意：获取空白活动,而不是将数据导入ListVIEw,没有收到任何错误
解决方法 JsON是有效的,但不合逻辑,应该是这样的[{"categoryID": "1","categoryTitle": "SmartPhones","SmartPhones": [ { "itemID": "1","itemTitle": "galaxy Mega 5.8" },"itemTitle": "galaxy Mega 6.3" } ]},{"categoryID": "1","categoryTitle": "tablets","tablets": [ { "itemID": "1","itemTitle": "galaxy Mega 6.3" } ]}] 那么代码将是：
if (categorIEs != null) { // looPing through All albums for (int i = 0; i < categorIEs.length(); i++) { JsONObject onecategory = categorIEs.getJsONObject(i); String categoryname = onecategory.getString(TAG_ID); String catTitle = onecategory.getString( TAG_Title ); JsONArray categoryTitle = onecategory.getJsONArray(catTitle); for( int i = 0 ; i < categoryTitle.length() ; i++ ) { JsONObject item = categoryTitle.getJsONObject(i); String ID = item.getString("itemID"); String name = item.getString("itemTitle"); // creating new HashMap HashMap<String,String>(); // adding each child node to HashMap key => value map.put(TAG_ID,ID); map.put(TAG_Title,name); } // adding HashList to ArrayList categorIEsList.add(map); } }else{ Log.d("CategorIEs: ","null"); } 总结 以上是内存溢出为你收集整理的android – 从JSON获取数据到List View全部内容，希望文章能够帮你解决android – 从JSON获取数据到List View所遇到的程序开发问题。
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