程序/ apk需要列出所有标题，但当我运行它apk关闭请帮助我我不知道发生了什么
package com.eu.agendamarinhagrande;
import android.annotation.TargetApi;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Build;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import com.eu.agendamarinhagrande.JSONParser;
import com.eu.agendamarinhagrande.R;
import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
public class MainActivity extends ActionBarActivity {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> empresaList;
// url to get all products list
private static String url_all_empresas = "http://www.grifin.pt/projectoamg/Conexao.php";
// JSON Node names
private static final String TAG_TITULO = "Titulo";
// products JSONArray
String resultado = null;
ListView lista;
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Hashmap para el ListView
empresaList = new ArrayList<HashMap<String, String>>();
LoadAllProducts loadAllProducts = new LoadAllProducts();
// Cargar los productos en el Background Thread
lista = (ListView) findViewById(R.id.agenda);
loadAllProducts.execute(String.valueOf(lista));
ActionBar actionBar = getSupportActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
}//fin onCreate
class LoadAllProducts extends AsyncTask<String, String, String> {
/**
* Antes de empezar el background thread Show Progress Dialog
*/
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("A carregar eventos. Por favor espere...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* obteniendo todos los productos
*/
protected String doInBackground(String... args) {
// Building Parameters
List params = new ArrayList();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_empresas, "GET", params);
StringBuilder sb = new StringBuilder();
// Check your log cat for JSON reponse
Log.d("All Products: ", url_all_empresas.toString());
resultado = sb.toString();
try {
// Checking for SUCCESS TAG
// products found
// Getting Array of Products
JSONArray arrayJson = new JSONArray(resultado);
for (int i = 0; i<arrayJson.length();i++){
// Storing each json item in variable
JSONObject c = arrayJson.getJSONObject(i);
String Titulo = c.getString(TAG_TITULO);
// creating new HashMap
HashMap map = new HashMap();
// adding each child node to HashMap key => value
map.put(TAG_TITULO, Titulo);
empresaList.add(map);
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
MainActivity.this,
empresaList,
R.layout.single_post,
new String[]{
TAG_TITULO
},
new int[]{
R.id.single_post_tv_id
});
// updating listview
//setListAdapter(adapter);
lista.setAdapter(adapter);
}
});
}
}
}
答案 0 :(得分：0)
在onCreate（）方法中检查此行：
loadAllProducts.execute(String.valueOf(lista));
你无法获得ListView的字符串值！如果要获取listView中textView的值，可以将一个OnItemClick事件添加到listView，并在所选列表项中获取textView的值，如下所示：
//a variable, you could use from all the methods, that will have as a value the value of the selected TextView
private String selectedValue;
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
View view = (View)v.getParent();
TextView textYouNeed = (TextView) view.findViewById(R.id.textViewId);
selectedValue = textYouNeed.getText();
}
然后在我上面讲述的那一行中使用这个变量：
loadAllProducts.execute(selectedValue);
答案 1 :(得分：0)
06-19 11:07:34.233 13804-13804/? I/art﹕ Not late-enabling -Xcheck:jni (already on)
06-19 11:07:34.380 13804-13818/com.eu.agendamarinhagrande I/art﹕ Background sticky concurrent mark sweep GC freed 1879(132KB) AllocSpace objects, 0(0B) LOS objects, 11% free, 538KB/605KB, paused 49.704ms total 65.759ms
06-19 11:07:34.380 13804-13804/com.eu.agendamarinhagrande D/AndroidRuntime﹕ Shutting down VM
06-19 11:07:34.380 13804-13804/com.eu.agendamarinhagrande E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.eu.agendamarinhagrande, PID: 13804
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.eu.agendamarinhagrande/com.eu.agendamarinhagrande.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setOnItemClickListener(android.widget.AdapterView$OnItemClickListener)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5257)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setOnItemClickListener(android.widget.AdapterView$OnItemClickListener)' on a null object reference
at com.eu.agendamarinhagrande.MainActivity.onCreate(MainActivity.java:75)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5257)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)