我学会在我的应用中使用JSON，但是有错误。我的列表视图显示了这些项目，但文本是空白的（只显示项目之间的行）。
我的代码
package com.example.belajarjson;
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.os.Build;
public class MainActivity extends ActionBarActivity {
private ProgressDialog pDialog;
// URL to get contacts JSON
private static String url = "http://192.168.1.100/json/contacts.php";
// JSON Node names
private static final String TAG_CONTACTS = "contacts";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_EMAIL = "email";
private static final String TAG_ADDRESS = "address";
private static final String TAG_GENDER = "gender";
private static final String TAG_PHONE = "phone";
private static final String TAG_PHONE_MOBILE = "mobile";
private static final String TAG_PHONE_HOME = "home";
private static final String TAG_PHONE_OFFICE = "office";
// contacts JSONArray
JSONArray contacts = null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> contactList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
contactList = new ArrayList<HashMap<String, String>>();
//JSON EXECUTING
new GetContacts().execute();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}
/**
* 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(MainActivity.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 jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
contacts = jsonObj.getJSONArray(TAG_CONTACTS);
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String id = c.getString(TAG_ID);
String name = c.getString(TAG_NAME);
String email = c.getString(TAG_EMAIL);
String address = c.getString(TAG_ADDRESS);
String gender = c.getString(TAG_GENDER);
// Phone node is JSON Object
JSONObject phone = c.getJSONObject(TAG_PHONE);
String mobile = phone.getString(TAG_PHONE_MOBILE);
String home = phone.getString(TAG_PHONE_HOME);
String office = phone.getString(TAG_PHONE_OFFICE);
// tmp hashmap for single contact
HashMap<String, String> contact = new HashMap<String, String>();
// adding each child node to HashMap key => value
contact.put(TAG_ID, id);
contact.put(TAG_NAME, name);
contact.put(TAG_EMAIL, email);
contact.put(TAG_PHONE_MOBILE, mobile);
// adding contact to contact list
contactList.add(contact);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
@Override
protected void onPostExecute(Void result) {
ListView lv = (ListView) findViewById(R.id.listView1);
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
MainActivity.this, contactList,
R.layout.fragment_main, new String[] { TAG_NAME, TAG_EMAIL,
TAG_PHONE_MOBILE }, new int[] { R.id.name,
R.id.email, R.id.mobile });
lv.setAdapter(adapter);
}
}
}
和我的布局xml
<RelativeLayout 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"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.belajarjson.MainActivity$PlaceholderFragment" >
<ListView
android:id="@+id/listView1"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:textColor="#000000"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true" >
</ListView>
</RelativeLayout>
你能帮我解决这段代码中的错误吗？谢谢：D
答案 0 :(得分：1)
问题来自您创建SimpleAdapter：
public SimpleAdapter (Context context, List<? extends Map<String, ?>> data, int resource, String[] from, int[] to)
resource参数应该是布局的ID，其中包含View个to参数中给出的ID。
这里（我猜）您传递的是Fragment的布局，而不是您已创建/需要创建的布局。
例如，创建此布局文件并将其命名为listview_row.xml：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/name"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/email"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/mobile"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
然后，按如下方式使用：
ListAdapter adapter = new SimpleAdapter(MainActivity.this,
contactList,
R.layout.listview_row,
new String[] { TAG_NAME, TAG_EMAIL, TAG_PHONE_MOBILE },
new int[] { R.id.name, R.id.email, R.id.mobile });
lv.setAdapter(adapter);