Listview和简单的适配器 [英] Listview and simple adapter
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问题描述
我正在向用户列出信息。当我调试信息成功时，列表视图没有显示任何输出。这意味着列表视图应该输出信息。没有显示信息。检查我的代码进行更正< br $> b $ b
我的尝试：
I am listing information to a user.the listview isn't bringing out any output,when i debug information is successful.so meaning the listview should output the information.nothing is showing for the information.check my code for corrections
What I have tried:
public class MainActivity extends AppCompatActivity {
private Toolbar toolbar;
private String TAG = MainActivity.class.getSimpleName();
private ProgressDialog pDialog;
private ListView lv;
// URL to get contacts JSON
private static String url = "http://..../EventMaster/api/Events/Upcomings";
ArrayList<HashMap<String, String>> EventList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setUpToolbar();
setUpDrawer();
EventList = new ArrayList<>();
lv = (ListView) findViewById(R.id.list);
new GetEvents().execute();
}
private void setUpToolbar() {
toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.setTitle("Event Master");
}
/**
* Async task class to get json by making HTTP call
*/
private class GetEvents extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
HttpHandler sh = new HttpHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url);
Log.e(TAG, "Response from url: " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
JSONArray events = jsonObj.getJSONArray("Model");
// looping through All Contacts
for (int i = 0; i < events.length(); i++) {
JSONObject c = events.getJSONObject(i);
String id = c.getString("EventId");
String name = c.getString("EventName");
String description = c.getString("Description");
String venue = c.getString("VenueName");
/** Phone node is JSON Object
JSONObject phone = c.getJSONObject("phone");
String mobile = phone.getString("mobile");
String home = phone.getString("home");
String office = phone.getString("office"); */
// tmp hash map for single contact
HashMap<String, String> event = new HashMap<>();
// adding each child node to HashMap key => value
event.put("EventId", id);
event.put("EventName", name);
event.put("Description", description);
event.put("VenueName", venue);
// adding contact to contact list
EventList.add(event);
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Json parsing error: " + e.getMessage(),
Toast.LENGTH_LONG)
.show();
}
});
}
} else {
Log.e(TAG, "Couldn't get json from server.");
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Couldn't get json from server. Check LogCat for possible errors!",
Toast.LENGTH_LONG)
.show();
}
});
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
MainActivity.this, EventList,
R.layout.event_item_list, new String[]{"name", "description",
"venue"}, new int[]{R.id.Eventname,
R.id.Eventdescription, R.id.Venue});
lv.setAdapter(adapter);
}
}
private void setUpDrawer() {
NavigationDrawerFragment drawerFragment = (NavigationDrawerFragment) getFragmentManager().findFragmentById(R.id.nav_drwr_fragment);
DrawerLayout drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
drawerFragment.setUpDrawer(R.id.nav_drwr_fragment, drawerLayout, toolbar);
}
}
推荐答案
我只是做了一点测试你的代码它的工作原理我怀疑从和到的值传递到SimpleAdapter构造函数与event_item_list.xml文件中的构造函数不匹配。
MainActivity .java：
I just did a little test using most of your code. It works so I suspect thefromandtovalues you are passing to theSimpleAdapterconstructor do not match those in theevent_item_list.xmlfile.
MainActivity.java:
public class MainActivity extends AppCompatActivity
{
ProgressDialog pDialog;
ArrayList<HashMap<String, String>> EventList;
ListView lv;
//================================================================
@Override
protected void onCreate( Bundle savedInstanceState )
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
EventList = new ArrayList<HashMap<String, String>>();
lv = (ListView) findViewById(android.R.id.list);
new GetEvents().execute();
}
//================================================================
//================================================================
private class GetEvents extends AsyncTask<Void, Void, Void>
{
@Override
protected void onPreExecute()
{
super.onPreExecute();
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
//============================================================
@Override
protected Void doInBackground(Void... arg0)
{
try
{
HashMap<String, String> event = new HashMap<>();
event.put("EventId", "ID1");
event.put("EventName", "Name1");
event.put("Description", "Description1");
event.put("VenueName", "Venue1");
EventList.add(event);
event = new HashMap<>();
event.put("EventId", "ID2");
event.put("EventName", "Name2");
event.put("Description", "Description2");
event.put("VenueName", "Venue2");
EventList.add(event);
event = new HashMap<>();
event.put("EventId", "ID3");
event.put("EventName", "Name3");
event.put("Description", "Description3");
event.put("VenueName", "Venue3");
EventList.add(event);
}
catch(Exception e)
{
Log.d("Test2", e.getMessage());
}
return null;
}
//============================================================
@Override
protected void onPostExecute(Void result)
{
super.onPostExecute(result);
if (pDialog != null)
pDialog.dismiss();
try
{
ListAdapter adapter = new SimpleAdapter(MainActivity.this,
EventList,
R.layout.event_row,
new String[]{"EventName", "Description", "VenueName"},
new int[]{R.id.Eventname, R.id.Eventdescription, R.id.Venue});
lv.setAdapter(adapter);
}
catch(Exception e)
{
Log.d("Test2", e.getMessage());
}
}
}
}
activity_main.xml：
activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.test.MainActivity">
<ListView android:id="@android:id/list"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
event_row.xml：
event_row.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView android:id="@+id/Eventname"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content" />
<TextView android:id="@+id/Eventdescription"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content" />
<TextView android:id="@+id/Venue"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content" />
</LinearLayout>
这篇关于Listview和简单的适配器的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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