Question

I’m pretty new to Android programming so any help would be great 🙂
I’m trying to get some dummy data remotely, parse the json response and display it within a listview.

This is the xml layout file i’m trying to use with the list activity:-

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <ListView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:id="@+id/list"
    />
</LinearLayout>

This is my http search activity:-

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.ListActivity;
import android.net.ParseException;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class searchResultActivity extends ListActivity {

    ListView listview;
    String result = null;
    InputStream is = null;
    StringBuilder sb = null;
    String url;
    String fd_name;
    ArrayList<String> listItems;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        /*setContentView(R.layout.test);
        listview = (ListView)findViewById(R.id.list);*/
        url = "http://pjchambers.comuf.com/index.php";
        new getData().execute();
    }

    public class getData extends AsyncTask<String, Void, ArrayList<String>> {

        protected ArrayList<String> doInBackground(String...urls) {
            // TODO Auto-generated method stub
            listItems = new ArrayList<String>();

            try {
                // Set of http statements setting up the connections to the php
                // and database
                HttpClient httpclient = new DefaultHttpClient();
                HttpGet httpget = new HttpGet(url);
                HttpResponse response = httpclient.execute(httpget);
                HttpEntity entity = response.getEntity();
                is = entity.getContent();
            } catch (Exception e) {
                Log.e("log_tag", "Error in http connection" + e.toString());
            }

            // convert response to string
            try {
                BufferedReader reader = new BufferedReader(
                        new InputStreamReader(is, "iso-8859-1"), 8);
                sb = new StringBuilder();
                sb.append(reader.readLine() + "\n");
                String line = "0";
                while ((line = reader.readLine()) != null) {
                    sb.append(line + "\n");
                }
                is.close();
                result = sb.toString();
            } catch (Exception e) {
                Log.e("log_tag", "Error converting result " + e.toString());
            }

            // paring data
            try {
                JSONArray jArray = new JSONArray(result);
                JSONObject json_data = null;
                for (int i = 0; i < jArray.length(); i++) {
                    json_data = jArray.getJSONObject(i);
                    fd_name = json_data.getString("Name");
                    listItems.add(fd_name);
                }
            } catch (JSONException e1) {
                Toast.makeText(getBaseContext(), "No Results Found",
                        Toast.LENGTH_LONG).show();
            } catch (ParseException e1) {
                e1.printStackTrace();
            }

            Log.d("debug", "- " + listItems.toString());
            return listItems;
        }

        protected void doPostExecute() {
            ArrayAdapter<String> adapter = new ArrayAdapter<String>(
                    searchResultActivity.this, android.R.layout.simple_list_item_1, R.id.list, listItems);
            setListAdapter(adapter);
        }

    }

}

I’ve spent hours trying different methods and approaches, using a few different online tutorials but they all end in the same result. As it stands the app works but the displays are displayed; however if i declare the layout in the onCreate methods the app crashes. any help or advice would be must appreciated, a fresh set of eyes might notice the issue(s) straight away

This is the logcat after I uncommented the two statements

05-22 12:12:20.234: D/debug(631): - [The Arena, Empire]
05-22 12:12:42.004: I/dalvikvm(691): threadid=3: reacting to signal 3
05-22 12:12:42.244: I/dalvikvm(691): Wrote stack traces to '/data/anr/traces.txt'
05-22 12:12:42.404: D/gralloc_goldfish(691): Emulator without GPU emulation detected.
05-22 12:12:48.415: I/dalvikvm(691): threadid=3: reacting to signal 3
05-22 12:12:48.424: I/dalvikvm(691): Wrote stack traces to '/data/anr/traces.txt'
05-22 12:12:50.595: D/AndroidRuntime(691): Shutting down VM
05-22 12:12:50.595: W/dalvikvm(691): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
05-22 12:12:50.614: E/AndroidRuntime(691): FATAL EXCEPTION: main
05-22 12:12:50.614: E/AndroidRuntime(691): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.project.barcrawl/com.project.barcrawl.searchResultActivity}: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list'
05-22 12:12:50.614: E/AndroidRuntime(691):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
05-22 12:12:50.614: E/AndroidRuntime(691):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
05-22 12:12:50.614: E/AndroidRuntime(691):  at android.app.ActivityThread.access$600(ActivityThread.java:123)
05-22 12:12:50.614: E/AndroidRuntime(691):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
05-22 12:12:50.614: E/AndroidRuntime(691):  at android.os.Handler.dispatchMessage(Handler.java:99)
05-22 12:12:50.614: E/AndroidRuntime(691):  at android.os.Looper.loop(Looper.java:137)
05-22 12:12:50.614: E/AndroidRuntime(691):  at android.app.ActivityThread.main(ActivityThread.java:4424)
05-22 12:12:50.614: E/AndroidRuntime(691):  at java.lang.reflect.Method.invokeNative(Native Method)
05-22 12:12:50.614: E/AndroidRuntime(691):  at java.lang.reflect.Method.invoke(Method.java:511)
05-22 12:12:50.614: E/AndroidRuntime(691):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
05-22 12:12:50.614: E/AndroidRuntime(691):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
05-22 12:12:50.614: E/AndroidRuntime(691):  at dalvik.system.NativeStart.main(Native Method)
05-22 12:12:50.614: E/AndroidRuntime(691): Caused by: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list'
05-22 12:12:50.614: E/AndroidRuntime(691):  at android.app.ListActivity.onContentChanged(ListActivity.java:243)
05-22 12:12:50.614: E/AndroidRuntime(691):  at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:254)
05-22 12:12:50.614: E/AndroidRuntime(691):  at android.app.Activity.setContentView(Activity.java:1835)
05-22 12:12:50.614: E/AndroidRuntime(691):  at com.project.barcrawl.searchResultActivity.onCreate(searchResultActivity.java:41)
05-22 12:12:50.614: E/AndroidRuntime(691):  at android.app.Activity.performCreate(Activity.java:4465)
05-22 12:12:50.614: E/AndroidRuntime(691):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
05-22 12:12:50.614: E/AndroidRuntime(691):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
05-22 12:12:50.614: E/AndroidRuntime(691):  ... 11 more
05-22 12:12:51.004: I/dalvikvm(691): threadid=3: reacting to signal 3
05-22 12:12:51.024: I/dalvikvm(691): Wrote stack traces to '/data/anr/traces.txt'

Answer 1

Your id in the XML should id="@android:id/list" then it should work. In your code a new id is created as part of “your” R.class which is different from android.R.id.list. Therefore the list view cannot be found and consequently the exception is thrown.

Also the third parameter of the ArrayAdapter constructor is supposed to be the id of the text resource to fill with the data. You are passing R.id.list which is wrong. For the resource defined by android.R.id.simple_list_item_1 it should be android.R.id.text1 if I’m not mistaken.